Read this first
This is an owner-level guide to one car. It is not VW or Audi documentation. Both cars were US-market, and wiring, fuses and equipment differ between markets, years and options. The owner calls his notes a guide, not a DIY, and says your car may vary1. Check every pin against the wiring diagram for your own car before you cut, splice or re-pin anything. Wrong wiring can cause fires, damage control units, stop the car, or disable airbags and other safety systems.
Two sources are used throughout: the owner's written swap notes (an engine wiring spreadsheet, wiring notes and a seat wiring spreadsheet)1, and the transcripts of a video build series covering the removal, the fitting and the wiring2. Where they differ, both are shown. For how to read the diagrams this work depends on, see Reading VW wiring diagrams.
Overview and donor facts
- Recipient
- 2019 US Golf R (a limited edition car), rear-ended and written off, bought back and repaired, then used for the swap2.
- Donor
- Wrecked 2018 US Audi RS31,2.
- Engine
- DAZA 2.5 TFSI five-cylinder2.
- Gearbox
- DQ500 DSG, removed with the engine as one unit2.
- Taken from the RS3
- Engine, gearbox, rear differential with Haldex coupling, rear driveshafts, rear brakes, fuel tank, fuel pump and pump module, side radiators, A/C and fuel lines, gearbox mount bracket, engine mounts, battery cabling and jump-start post, engine wiring and part of the fuse panel2,1.
- Kept from the Golf R
- Brake booster, under-bonnet fuse panel (adapted), rear subframe, rear knuckles, rear diff top plate, ABS bracket, accelerator pedal2.
Both cars are built on VW's MQB platform. The owner found the brake booster almost identical between them, and the engine and gearbox bolted into the Golf without fitment problems2. Adapting the Golf's fuse panel to the RS3 powertrain was easier than adapting the body to the RS3 panel2.
Planning and donor inspection
The donor RS3 had been modified before it was written off, and parts had been stripped. The owner found a hollowed-out catalytic converter, loose and broken bolts, and E85 in the tank. The lesson he drew: inspect a donor thoroughly before buying2.
- Get the factory wiring diagrams for both cars, the Golf 2.0 and the RS3 2.5, before starting2. See Getting the wiring diagrams.
- Budget time for the wiring: the owner spent about a week of evenings studying the diagrams, a day building his pin document and about four full days wiring2.
- Decide early which parts come from which car: several RS3 parts did not suit the Golf, and several Golf parts had to be kept (see below)2.
Removal order
| Step | RS3 (donor) | Golf R | Source |
|---|---|---|---|
| 1 | Wheels, arch liners, bumper cover | Front end | [2] |
| 2 | Drain coolant | Subframe | [2] |
| 3 | Front end (radiator, condenser and intercooler carrier) | Downpipe | [2] |
| 4 | Exhaust | Pendulum mount | [2] |
| 5 | Propshaft, separated with a clamp-type propshaft tool | Propshaft | [2] |
| 6 | Subframe | Driveshafts | [2] |
| 7 | Driveshafts | Engine and gearbox out | [2] |
| 8 | Engine and gearbox lowered out as one unit | [2] |
Driveshaft and propshaft removal was easier on the Golf2.
Engine bay preparation
| Item | What was done | Source |
|---|---|---|
| Engine mount access | The RS3 engine mount is one piece where the Golf's is two. The owner drilled an access hole of about 38 mm (1.5 in) to reach the mount's rear bolt, and painted the edge. | [2] |
| Gearbox mount bracket | The RS3 bracket is stronger and was fitted to the Golf. | [2] |
| A/C lines | Close between the cars but different at the engine end. RS3 lines fitted; one line carries the high and low sides coaxially. | [2] |
| Fuel lines | RS3 lines fitted. Line sizes differ between the cars; the details were not clear. | [2] |
| ABS heat shield | The RS3 has a heat shield over the ABS unit for the extra turbo heat of the five-cylinder. The RS3 bracket uses two studs, the Golf R's one stud and a hole. The owner kept the Golf bracket and modified the RS3 shield to fit. | [2] |
| Frame-rail studs | Studs on the passenger-side frame rail (for the washer bottle) sat millimetres from the RS3 water pump pulley. The owner cut them off. | [2] |
| Brake booster | Golf R part kept; almost identical MQB part. | [2] |
| Under-bonnet fuse panel | Golf R panel kept and adapted to the RS3 powertrain. See Engine wiring. | [2] |
| Downpipe | Fitted after the engine was in. | [2] |
Cooling and intercooler
- The RS3 has extra side radiators, bigger than and different from the Golf R's2. The RS3's two auxiliary front coolers bolted to mounting points already on the Golf R2.
- The stock RS3 intercooler is a thicker bar-and-plate design: more efficient but heavier than the Golf R's2. The options were the Golf intercooler, the RS3 one or an upgraded aftermarket one; the choice was left for later2.
- Charge-pipe clips are fragile. The owner cut the core support to save them2.
Rear axle and running gear
| Part | What was done | Source |
|---|---|---|
| Rear differential and Haldex coupling | From the RS3, fitted into the Golf subframe. The Haldex connector was hard to release. | [2] |
| Subframe and diff top plate | Golf parts kept because the RS3 ones were corroded. | [2] |
| Driveshafts | RS3 driveshafts differ from the Golf R's and were needed with the RS3 diff. | [2] |
| Rear anti-roll bar | The Golf R bar fouls the RS3 diff. A different bar is needed; not yet sourced in the video. | [2] |
| Knuckles | Golf knuckles kept: fresher bearings and ball joints, and no unknown offset or track change from RS3 knuckles. | [2] |
| Rear links | Aftermarket rear trailing arms with spherical bearings. Other links were a mix, some from the owner's MK8 Golf, which have different part numbers but were expected to fit Unverified. | [2] |
| Calipers | The video calls the RS3 calipers larger than the Golf R's, and at one point the same Unverified. | [2] |
| Brake backing plates | The Golf R dust shield fouled. The RS3 one was fitted; the RS3 has ventilation ducting through air deflectors on the control arms. | [2] |
| Rotors | The RS3 wheel bearing puts the rotor about 4 mm further out, so RS3 rotors did not fit the Golf hub and caliper carrier. The owner sourced different rotors; the exact type is not clear from the video. | [2] |
| Brake lines | New aftermarket lines. | [2] |
Fuel system and tank
- The RS3 fuel pump and fuel pump control module differ from the Golf R's. The owner fitted the RS3 fuel tank too; it may siphon better internally, but that is not confirmed Unverified2.
- The RS3 pump is brushless with more wires; an extra ground was added2.
- Both cars feed the fuel pump control module from fuse SB101. The wiring to the module is the same; the wiring from the module to the pump differs. The plan was to depin the connectors and pin the Golf wiring into the RS3 connector, leaving the cluster connector alone1. The RS3 pump module connector differs, and the RS3 pigtail was spliced into the Golf harness2.
Battery relocation and cable routing
The RS3 battery lives in the boot, so its cabling came across too2.
- The RS3 positive cable runs along the frame rail to the engine bay. The owner moved it and the jump-start junction to the Golf: rivets drilled out of the RS3 and new rivets set in the Golf2.
- The Golf has no floor studs for the cable clips. The owner welded studs on and painted them, and drilled a pass-through hole using a template measured off the RS32.
- As built: the positive cable goes through one hole in the driver's-side floor, along the side of the boot to a circuit breaker, then to the battery2.
- This owner used two 6 V batteries in series. That is his choice, not RS3 standard2.
- The negative uses the RS3 cable with its battery monitoring module, run to a ground stud welded to the passenger-side floor at the lower A-pillar2.
- A jump-start post was added under the bonnet because the battery is in the boot2.
Mounts
The engine and gearbox mounts were replaced with new factory RS3 mounts because the old ones were worn. The owner chose factory mounts over harder aftermarket ones to avoid vibration2.
Shifter problem
The RS3 and Golf shifter boxes and cable brackets differ. The RS3 shifter sat far too high in the Golf, and mixing parts from the two did not work. The owner was trying the lower bracket from a Golf GTD; the result was not shown2.
Getting the wiring diagrams
The owner bought one-day access, with printing rights, to VW's and Audi's US factory repair information sites (erWin) at about US$35 each, and downloaded everything he needed within the 24 hours2. Bentley manuals do not exist for these cars2. He needed both the Golf 2.0 and the RS3 2.5 diagrams2.
How to get the same information from the UK or Europe was not covered Unverified. How the diagrams are laid out and read is on Reading VW wiring diagrams.
Engine wiring
The approach
Only the body side of the engine control unit harness was changed; the engine side stayed as the RS3 built it1,2. The body-side connector is T91, a 91-pin plug at the ECU. The owner built a pin-by-pin table of Golf R against RS3 T91 functions, colours and routes, bought a new T91 connector and depinned wires into it1. About 90% of wires were depinned and repinned, and a handful were cut and spliced2. The video puts it at about four or five splices for 75–80 wires moved2.
The four big under-bonnet jobs2:
- ECU: of its two connectors, the upper (engine side) was untouched and the lower 91-pin (body side) was completely repinned.
- Junction connectors on the frame rail: the engine side was untouched; the grey connector came from the RS3 and was repinned; the black connector changed (10-pin on the Golf, 8-pin on the RS3).
- Under-bonnet fuse panel: a whole leg of fuses added from the RS3, some relays different, and many pins moved between positions or brought from the Audi panel.
- Jump-start post, because the RS3 battery lives in the boot.
Depinning and repinning
- Remove the connector's secondary lock (a purple slide on these plugs)2.
- Release the primary lock with a depinning tool, which pushes in the retaining tabs, and pull the wire out2.
- Push the terminal into its new cavity until it clicks, then refit the secondary lock2.
On the 91-pin connector the six large cavities are the powers and grounds. Pin numbers are printed only at the ends, so count carefully; the owner miscounted three or four times2. Label everything with masking-tape flags2. Splices were made with crimp butt connectors and heat shrink, sealed only after testing. The owner says this matches VW and Audi repair practice Unverified2.
Pedal example
The Golf accelerator pedal was kept. Its pin 1 wire sits in Golf ECU T91/16, but the RS3 ECU expects it in T91/65, so it moved from 16 to 65. Pin 2 moved from 33 to 82, and pin 3 from 34 to 842,1. The wire colours then do not match the Audi diagram, but the positions are right2.
Powers, grounds and fuses
- The RS3 has three powers and three grounds on T91; the Golf R has two and two. The owner moved all six from the RS3 harness to the new T91 and put the powers into fuse SB31.
- The RS3 engine-bay fuse box has extra fuses and relays, and some fuses feed different circuits than on the Golf1.
Junction connectors T8, T10 and T14
- The Golf R has a black 10-pin and a grey 14-pin junction on the driver-side frame rail; the RS3 has a grey 14-pin and a black 8-pin (T8). The grey connector was moved over. The larger pin 9 ground in the RS3 grey connector was swapped for the one from the Golf R; the smaller one had to be spliced, using a ground from the Golf R mechatronic unit connector1.
- T8/4 goes to the A/C compressor solenoid and was spliced to the green/black wire from the Golf R harness, so the RS3 harness matched T8 at that position1.
- T8/8 was spliced to the feed from ECU T91/50 to the ABS module, J519 and the steering rack (T6/1). That RS3 splice section was removed and the Golf R gearbox connector's T16/16 was spliced into T8/8 instead1.
- The powertrain CAN wires were spliced into the twisted pair from the Golf R gearbox plug1.
- T8/1 runs into the car to the battery monitoring module at the rear. Golf R T10/1 was depinned and pinned into T8/1, with a splice inside the car to connect the gateway J533 to the battery module1.
- T8/2, a green/blue wire, goes to ECU T91/60. It is not on the ECU diagram and the owner found no information on it; he fitted it because it was in the RS3 harness Unverified1.
Circuit by circuit
| Circuit | What differs and what was done | Source |
|---|---|---|
| Leak detection pump J909 and charcoal canister | Use the RS3 parts; wiring and connector pins differ, so the connector was cut and spliced. The RS3 feeds J909 from SC20 or SB7 depending on equipment (SC20 on this car). The owner's first attempt was to power it from SB38; SB32 is live when J271 (ECU power relay) is, as on the Golf R. T91/64 was spliced because the RS3 wire (0.35 mm²) and the Golf wire (1.0 mm²) differ in size. | [1] [2] |
| Fuel pump | Both cars feed the pump control module from SB10. The RS3 pump and module were used. See Fuel system. | [1] |
| G265 intermediate shaft speed sensor (RS3) | Three wires to the ECU through junction TML (the grey 14-pin on the driver-side frame rail). Depinned from the RS3 T91 and TML, pinned into the Golf TML and T91. | [1] |
| Exhaust flaps J945 and J883 | Fuse SB9 on the Golf and SB5 on the RS3, both shared with other engine parts. The Golf's splice is deep in the harness, so the SB5 circuit was taken out of the RS3 harness, fitted at SB5 in the Golf harness and through TML, and spliced to the flap power wire. Flap ground from the Golf R; control wires moved on T91. The lilac wire from RS3 T91/77 was spliced into the new T91/77 because the Golf wire from T91/91 was too thick for that cavity. | [1] |
| J976 engine component relay 2 | RS3 only. It feeds SB14 and SB31, which have no fuses or pins on the Golf R. The owner took the whole fuse holder from the RS3, with the white/yellow wire into one bridge and the red/white wire bolted to the other, and put a black/green wire into the grey 14-pin connector. | [1] |
| J757 | Deleted on the Golf and replaced by J976. | [1] |
| V475 gearbox auxiliary oil pump | The Golf R's 4-pin connector at the back of the driver-side frame rail was eliminated. Fuse SB13 was removed and replaced by a pin to the RS3 T8. The owner saw this as a possible place to tap the powertrain CAN wires. | [1] |
| G83 radiator outlet temperature (Golf R T91/29 and T91/49) | Not used. | [1] |
| J527 steering column electronics | The diagram lists options by equipment, such as a heated steering wheel. The owner moved Golf T91/68 to RS3 T91/71 and Golf T91/70 to RS3 T91/28, and marks this as a guess Unverified. | [1] |
| Gearbox control unit lines | On the Golf R, T91/60 is the brake switch signal; on the RS3, T91/41 is the J743 gearbox line. DQ381 and DQ500 swappers report that gearbox plug pins 2 and 4 go to T91/60 and T91/41 Unverified. See DQ381 swap. | [1] [3] |
T91 pin table
From the owner's spreadsheet, with his labels kept. "Moved here" means the wire that sat in the named Golf R T91 position was moved to this RS3 position. Colours are VW's wire colours as the owner read them. Pins 13, 14, 18, 21, 24, 27, 30, 31, 36, 45–47, 57, 63, 81 and 85 have no entry for either car and are left out. Items the owner marked as a guess or was unsure of are tagged.
| T91 pin | Golf R function (colour) | RS3 function (colour) | What was done, notes | Source |
|---|---|---|---|---|
| 1 | Ground 138 (Brown) | Ground (Brown/Black). Splice 209, left frame rail | RS3 wire used. Colour could be black/brown Unverified | [1] |
| 2 | Ground 671 (Brown) | Ground (Brown/Black). Splice 209, left frame rail | RS3 wire used | [1] |
| 3 | SB3 (Red/White). D183 87A | RS3 wire used | [1] | |
| 4 | Ground (Brown/Black). Splice 209, left frame rail | RS3 wire used | [1] | |
| 5 | SB3 (Red/Green). KL87a | SB3 (Red/White). D183 87A | RS3 wire used. Colour could be white/red Unverified | [1] |
| 6 | SB3 (Red/Green). KL87a | SB3 (Red/White). D183 87A | RS3 wire used | [1] |
| 7 | J271 control ECM Power Supply (Black/Green). ECM pwr Relay | [1] | ||
| 8 | J757 control Engine COMP Power Supply (Lilac). ECM pwr Relay | J299 2nd Air (Yellow/Blue) | RS3 wire used | [1] |
| 9 | J538 control Fuel pump (Black/Brown). T17o/13 T17g/13 | [1] | ||
| 10 | J945 Exhaust 2 (Lilac). TIUL 17o/2. T17g/2 | [1] | ||
| 11 | GX7 Downstream O2 (VS) (Red/Lilac) | [1] | ||
| 12 | VX57 Radiator Fan (Yellow/Lilac) | [1] | ||
| 15 | GX10 Upstream O2 (Red) | Golf R wire from T91/41 (Red) moved here | [1] | |
| 16 | GX2 Throttle (VS5v) (Grey/Black) | GX10 Upstream O2 (Lilac) | Golf R wire from T91/44 (Yellow) moved here | [1] |
| 17 | G701 Trans Neutral Switch (VS5v) (Yellow/Grey). Manual trans Start stop | [1] | ||
| 19 | G701 Trans neutral Switch (Brown). Manual trans Start stop | [1] | ||
| 20 | F Brake light (Grey/Green) | Golf R wire from T91/60 (Black/Red) moved here | [1] | |
| 22 | N82 Coolant Shutoff (Green/Grey). TML T14l/3 T14m/3 | GX7 Downstream O2 (Lilac). O2 Heater | Golf R wire from T91/11 (Red/Lilac) moved here. Diagram breakout slightly different | [1] |
| 23 | J909 control LDP (Green/Brown). TIUL T17n/3,T17f/3 | [1] | ||
| 25 | GX7 Downstream O2 (SIG+) (Grey/Red) | [1] | ||
| 26 | GX7 Downstream O2 (SIG-) (Grey/White) | [1] | ||
| 28 | J527 steering Col electrics (Lilac/Red). TALU T17hx/12 T17h/12 | J527 wires: the owner moved Golf R T91/68 to RS3 T91/71 and Golf R T91/70 to RS3 T91/28, and marks this as a guess Unverified | [1] | |
| 29 | G83 Radiator outlet temp (Brown) | [1] | ||
| 32 | G31 Charge air (VS5v) (Green). TML T8o/7. T8p/7 | GX10 Upstream O2 (Grey) | Golf R wire from T91/42 (Grey/black) moved here | [1] |
| 33 | Gx2 Throttle Pedal (VS5v) (Yellow/Green) | GX10 Upstream O2 (Brown Yellow) | Golf R wire from T91/43 (Grey) moved here | [1] |
| 34 | Gx2 Throttle Pedal (GND) (Grey/Red) | [1] | ||
| 35 | G31 Charge air (GND) (Brown). TML t8o/5. T8p/5 | [1] | ||
| 37 | F Brake Switch (SIG) (Black/Red). In Splice D73 | [1] | ||
| 38 | J909 Ground LDP (Brown). TIUL T17o/11 T17g/11 | G265 Intermediate Shaft Speed (Red/Blue). TML 14aa/2. T14aax/2 | RS3 wire used | [1] |
| 39 | N488 (Sig) (Blue/Green). TML T10af/10 T10ag/10 | GX36 LDP (Lilac/Blue). TALU T17kx/2 T17k2 | Not applicable. TALU is listed twice | [1] |
| 40 | J909 control LDP (Grey/Blue). TIUL T17n/7 T17f/7 | J909 LDP (Blue/Lilac). TALU T17kx/2 T17k2 | Golf R wire from T91/40 (Grey/Blue) moved here. THRR T5afx/3. T5af/3 | [1] |
| 41 | GX10 Upstream O2 (Sig +) (Brown/Yellow). Could be Red wire | J743 DSG (Green/Grey). TML T14aa/3 T14aax/3 | DSG diagram is separate Unverified | [1] |
| 42 | GX10 Upstream O2 (sig-H) (Grey/Black) | J538 Fuel pump mod (Black/Brown). TALU T17hx/13. T17h/13 | Golf R wire from T91/9 (Black/Brown) moved here. TAK T3DMX/1 T3dm/1 | [1] |
| 43 | GX10 Upstream O2 SIG (White/Yellow). Could be Grey | Unverified | [1] | |
| 44 | GX10 Upstream O2 (sig -) (Green/Lilac). Could be Yellow | G265 Intermediate Shaft Speed (Blue/Green). TML T14aa/1 T14aax/1 | RS3 wire used Unverified | [1] |
| 48 | GX7 Downstream O2 (Green) | Golf R wire from T91/25 (Grey/Red) moved here. Diagram breakout slightly different | [1] | |
| 49 | G83 Radiator outlet temp (Black) | GX7 Downstream O2 (Brown) | Golf R wire from T91/26 (Grey/White) moved here. Diagram breakout slightly different | [1] |
| 50 | D51 SIG15(15 power?) (Black/Lilac). J104, J743, J519, J533 | J519 Electrics module (D109) (White/Blue). TALU T17jx/4 T17j/4 (B466) | Golf R wire from T91/50 (Black/Lilac) moved here Unverified | [1] |
| 51 | GX2 Throttle Pedal (GND) (Grey/Blue) | [1] | ||
| 52 | GX2 Throttle Pedal (SIG) (White/Blue) | [1] | ||
| 53 | G265 Intermediate Shaft Speed (Yellow/Blue). TML T14aa/11. T14aax/11 | RS3 wire used | [1] | |
| 54 | G31 Charge air (SIG) (Yellow). TML T8o/6. T8p/6 | [1] | ||
| 55 | G31 Charge air (SIG) (Black). TML T8o/8 T8p/8 | [1] | ||
| 56 | J945 Exhaust Door 2 (Blue/Grey). TALU T17hx/5 T17h/5 | Golf R wire from T91/10 (Lilac) moved here | [1] | |
| 58 | J976 ECM Component relay (Green) | RS3 wire used | [1] | |
| 59 | Wire to the 8-pin "TCM" junction (Green/Blue). Not listed on the T91 wiring diagram; the owner could not identify it | Unverified | [1] | |
| 60 | F Brake Switch (SIG) (Black/Red) | [1] | ||
| 61 | G476 Clutch Pos Switch (SIG) (White/Red). Manual trans only | [1] | ||
| 62 | G476 Clutch Pos Switch (SIG) (Lilac/White). Manual trans only D102 OR J743 | [1] | ||
| 64 | G701 Trans Neutral Switch (Yellow/Brown). Manual trans Start stop | J909 LDP (Brown/Grey). TALU T17kx/1. T17k/1 | Golf R wire from T91/23 spliced to the RS3 wire (different wire size). THRR T5afx/2 T5af/2 | [1] |
| 65 | GX2 Throttle Pedal (Yellow/Blue) | Golf R wire from T91/16 (Black/Grey) moved here | [1] | |
| 66 | GX2 Throttle Pedal (Grey/Yellow) | Golf R wire from T91/69 (Brown/Grey) moved here | [1] | |
| 67 | SB 22 (Red/Black). Power From starter relay | GX2 Throttle Pedal (Grey) | Golf R wire from T91/51 (Grey/Blue) moved here | [1] |
| 68 | J965 SIG50 (Access start) (Black/Red). T17o/5 T17g/5 | F Brake light switch (Black/Red). Splice D73 | Golf R wire from T91/37 (Black/Red) moved here | [1] |
| 69 | GX2 Throttle (SIG) (Brown/Grey) | [1] | ||
| 70 | J527 (SIG) Steering electric (Black/White). T17o/12. T17g/12 | [1] | ||
| 71 | J518,J764,D, J527 (Red/Black). TALU T17hx/9 T17h/9 | J527 wires: the owner moved Golf R T91/68 to RS3 T91/71 and Golf R T91/70 to RS3 T91/28, and marks this as a guess Unverified | [1] | |
| 72 | G 506 Pre Particulate Filter sensor (SIG) (White/Lilac). Europe only? | Unverified | [1] | |
| 73 | J293 Radiator fan Module (Lilac/Grey) | RS3 wire used | [1] | |
| 74 | GX10 Upstream O2 control (Lilac/Green). 2 different GX10 Options | GX36 LDP (Red/Grey). T17kx/1 T17k1 | Not used. Could be either GX36 or J909 Unverified | [1] |
| 75 | J906 Starter 1 (Brown/Green) | Golf R wire from T91/87 (White/Red) moved here | [1] | |
| 76 | J907 Starter 2 (Brown/Red) | Golf R wire from T91/88 (Yellow/White) moved here | [1] | |
| 77 | J883 Exhaust Door (Lilac). TALU T17hx/1 T17h/1 | Golf R wire from T91/91 (Lilac) moved here. RS3 wire spliced in because of the different wire size | [1] | |
| 78 | J909 LDP (Yellow/black). TIUL T170/9. T17g/9 (could be black/yellow) | Unverified | [1] | |
| 79 | J533 Gateway Can-H B384 (Orange/Black). TIUL T17m/1 T17e/1 B383 | J533 Gateway CAN H (E123) (Orange/Black). Also Goes to J743 DSG | Golf R wire from T91/79 (Black) moved here. Passes TALU & GEN 1 | [1] |
| 80 | J533 Gateway Can-L B391 (Orange/Brown). TIUL T17m/2 T17e/2 B390 | J533 Gateway Can L (E124) (Orange/Brown). Also Goes to J743 DSG | Golf R wire from T91/80 (Orange/Brown) moved here. Passes TALU & GEN 1 | [1] |
| 82 | GX2 Throttle Pedal (Black/Yellow) | Golf R wire from T91/33 (Yellow/Green) moved here | [1] | |
| 83 | GX2 Throttle Pedal (Grey/Yellow) | Golf R wire from T91/52 (Blue/White) moved here | [1] | |
| 84 | GX2 Throttle Pedal (Green/Brown) | Golf R wire from T91/34 (Grey/Red) moved here | [1] | |
| 86 | FROM SB17 (Red/Black). 30power J271 104 | J271 & SB17 (Black/Lilac). D78 30a | Golf R wire from T91/87 (Red/Black) moved here. ECM power supply relay | [1] |
| 87 | J906 Starter relay 1 (White/Red). KL50 | J271 ECM power supply (Red/Green). Ground side of relay | RS3 wire used | [1] |
| 88 | J907 Starter relay 2 (White/Yellow). KL50 | SB22 (Red/Black). Powered after starter relay 2 | Golf R wire from T91/67 (Red/Black) moved here | [1] |
| 89 | G527 POST Particulate Filter Temp sensor (SIG) (White/Black). Europe Only? | Unverified | [1] | |
| 90 | GX10 Upstream O2 (Lilac). O2 Heater | Wire colour noted: Lilac/Green | [1] | |
| 91 | J883 Exhaust SIG (Blue/Red). TIUL T17o/1 T17g/1 | [1] |
ECU, immobiliser and keys
Defeating the immobiliser in an engine control unit removes a security system. It makes the car easier to steal and can affect insurance cover. Check with your insurer before doing it.
First start
The car started on the first attempt after the wiring was finished2. A flex-fuel kit and upgraded port injectors were planned2.
Open issues
- Rear anti-roll bar: the Golf R bar does not clear the RS3 diff, and no replacement had been found2.
- Shifter: the RS3 shifter sits too high; the Golf GTD bracket was being tried2.
- Intercooler: Golf, RS3 or aftermarket, not yet decided2.
- Leak detection pump fuse: SB38 was a first attempt1.
- J527 wiring is marked a guess, and T8/2 to T91/60 is unidentified1.
- Brake caliper sizes are inconsistent in the video2.
The owner's tips
RS3 seats into a MK7.5 Golf R
These connectors carry airbag and seat-occupancy circuits: belt switches, seat position senders and passenger occupant detection, all wired to the airbag control unit J234. A fault or wrong wiring can disable airbags or make them deploy wrongly. Work only with the battery disconnected, and follow VW's airbag safety procedures for handling seats and connectors.
The owner fitted 2018 RS3 seats to his 2019 Golf R and mapped each Golf R seat connector to the RS3 seat connectors, with wire sizes, colours and destinations. He calls it a guide for his car only, not a DIY1. The Golf seat has two connectors; the Audi seat has four, and the splices differ, so the job was harder than the engine wiring2,1. Sizes are in mm². "Far side" is the colour on the other side of the named connector. The RS3's fourth connector (T3) has no entries.
Driver's seat: Golf R connector T17u
| Pin | Size | Colour | From | To | Other connector, notes | Source |
|---|---|---|---|---|---|---|
| 17u/1 | 0.5 | Green/Red | Airbag J234 T90/35 | E24 belt switch | [1] | |
| 17u/2 | 0.5 | Brown | Airbag J234 T90/63 | E24 belt switch | [1] | |
| 17u/6 | 0.5 | Black/Brown | Airbag J234 T90/36 | G553 seat position sender | T3BR/2 (blue on the far side) | [1] |
| 17u/7 | 0.5 | Brown | Airbag J234 T90/63 | G553 seat position sender | T3BR/1 | [1] |
| 17u/11 | 0.5 | Brown/Black | J519 T73c/43 | G344 seat heating temperature sensor | T4I/3 | [1] |
| 17u/12 | 0.5 | Brown/Yellow | J519 T73c/56 | G344 seat heating temperature sensor | T4I/2 | [1] |
| 17u/13 | 0.35 | Orange/Black | CAN high | Green on the far side | [1] | |
| 17u/14 | 0.35 | Orange/Brown | CAN low | [1] | ||
| 17u/15 | 1.5 | Red/Black | Fuse SC45 | E470, E176, J810 | [1] | |
| 17u/16 | 2.5 | Brown | Ground, lower A-pillar | Power seat (ZX15) | T4I/4 | [1] |
| 17u/17 | 1.0 | Red/White | J519 T73c/2 | Power seat (ZX15) | T4I/1 | [1] |
Pins 3, 4, 5, 8, 9 and 10 have no entry. The sheet also gives the connector as T17t.
Driver's seat: RS3 connectors T6i, T5 and T10d
| Pin | Size | Colour | From | To | Other connector, notes | Source |
|---|---|---|---|---|---|---|
| T6i/1 | 0.5 | Green/Brown | J519 T73c/56 | G344 temperature sensor | Black/Yellow on the far side | [1] |
| T6i/2 | 0.5 | White/Yellow or Red/Lilac | J519 T73c/43 | G344 temperature sensor | Brown/Yellow on the far side | [1] |
| T6i/3 | 2.5 | Brown | Z6/Z7 seat heating | T2r/1 | [1] | |
| T6i/4 | 2.5 | Red/Yellow | J519 T73a/2 | Z6/Z7 seat heating | T2r/2 (Black/Lilac on the far side) | [1] |
| T5/1 | 0.5 | Brown | Airbag J234 T90/63 | E24 belt switch, G553 seat position | T2gn/1 | [1] |
| T5/2 | 0.35 | Green/Red | Airbag J234 T90/35 | E24 belt switch | T2gn/2 (Green/Yellow on the far side) | [1] |
| T5/3 | Black/Yellow on the far side | [1] | ||||
| T5/4 | 0.5 | Black/Brown | Airbag J234 T90/36 | G553 seat position | [1] | |
| T10d/2 | 0.5 | Grey/Yellow | J519 T73c/72 | W45 footwell light | T2mk/2 (Red/Green on the far side) | [1] |
| T10d/3 | 0.5 | Brown | Ground, left side member | W45 footwell light | T2mk/1 (Brown/Green on the far side) | [1] |
| T10d/4 | 1.0 | Blue/Red | Fuse SC45 | E470 | T6x/2, 4, 6 (1.5 red on the far side) | [1] |
| T10d/5 | 1.5 | Brown | Ground, left side member | E176 | T6cr/4 | [1] |
| T10d/8 | 0.35 | Grey/Yellow | Airbag J234 T90/8 | E470 driver height control | T10ar/3. Not on the owner's car | [1] |
Passenger seat: Golf R connector T17v
| Pin | Size | Colour | From | To | Other connector, notes | Source |
|---|---|---|---|---|---|---|
| 17v/1 | 0.5 | Green/Yellow | Airbag J234 T90/33 | E25 belt switch | T2ge/1 | [1] |
| 17v/2 | 0.5 | Brown | Airbag J234 T90/63 | E25 belt switch | T2ge/2 | [1] |
| 17v/3 | 0.35 | Black/Red | Fuse SC33 | J706 occupant detection T10z/9 | Red/Yellow on the far side | [1] |
| 17v/4 | 0.35 | Lilac/Black | Airbag J234 T90/64 | J706 occupant detection T10z/7 | [1] | |
| 17v/6 | 0.5 | Black/Yellow | Airbag J234 T90/34 | G554 seat position sender | T3cl/2 (blue on the far side) | [1] |
| 17v/7 | 0.5 | Brown | Airbag J234 T90/63 | G554 seat position sender | T3cl/1 | [1] |
| 17v/11 | 0.5 | Brown/Blue | J519 T73c/40 | G452 T6dc/3, occupant detection pressure sensor | [1] | |
| 17v/12 | 0.5 | Brown/Yellow | J519 T73c/52 | G452 T6dc/4, occupant detection pressure sensor | [1] | |
| 17v/15 | 1.5 | Black/Red | Fuse SC45 | Lumbar, owner unsure Unverified | [1] | |
| 17v/16 | 1.5 | Brown | Ground (638) | Listed as J706 T10z/7 Unverified | [1] | |
| 17v/17 | 1.0 | Red/Yellow | T73a/5 (the sheet says J529) Unverified | Listed as J706 T10z/10 Unverified | [1] |
Pins 5, 8, 9, 10, 13 and 14 have no entry.
Passenger seat: RS3 connectors T6j, T5 and T10e
| Pin | Size | Colour | From | To | Other connector, notes | Source |
|---|---|---|---|---|---|---|
| T6j/1 | 0.5 | Green/Brown | J519 T73c/56 | G345 temperature sensor | Brown/Yellow on the far side | [1] |
| T6j/2 | 0.5 | White/Lilac | J519 T73c/40 | G345 temperature sensor | [1] | |
| T6j/3 | 2.5 | Brown | Ground, A-pillar | Z8/Z9 seat heating | Brown/White on the far side | [1] |
| T6j/4 | 2.5 | Red/Lilac | J519 T73a/5 | Z8/Z9 seat heating | T2s/2, Z9 only (Black/Lilac on the far side) | [1] |
| T5/1 | 0.5 | Brown | Airbag J234 T90/63 | E25 belt switch | T2fz/1 (Black/Brown on the far side) | [1] |
| T5/2 | 0.5 | Green/Yellow | Airbag J234 T90/33 | E25 belt switch | T2fz/2 | [1] |
| T5/3 | 0.5 | Blue | Airbag J234 T90/64 | J706 occupant detection | T3ab/2 | [1] |
| T5/4 | 0.5 | Black/Yellow | Airbag J234 T90/34 | G554 seat position | Red on the far side | [1] |
| T5/5 | 0.5 | Black | Fuse SC33 | J706 occupant detection | T3ab/1 (Red/Black on the far side) | [1] |
| T10e/2 | 0.5 | Grey/Yellow | Footwell light splice | W46 footwell light | Red/Green on the far side | [1] |
| T10e/3 | 0.5 | Brown | Ground | W46 footwell light | Brown/Green on the far side | [1] |
| T10e/4 | 1.0 | Blue/Red | Fuse SC2 | E471 and/or E177 | Diagram shows S46, a seat circuit breaker, with no more detail | [1] |
| T10e/5 | 1.5 | Brown | Ground, A-pillar | E176/E177 lumbar | [1] |
Functions on these maps: seat heating elements (Z6/Z7 driver, Z8/Z9 passenger) and their temperature sensors (G344, G345) on the BCM J519; belt switches (E24, E25) and seat position senders (G553, G554) on the airbag unit J234; passenger occupant detection (J706 and pressure sensor G452); footwell lights (W45, W46); lumbar and height motors (E176/E177, E470/E471) on fuses SC45 and SC2; and grounds1. The Golf R sheet routes the passenger seat's pressure sensor to J519 T73c/40, which the RS3 sheet uses for the G345 temperature sensor; check this against your diagrams Unverified1.
Sources
- Owner's swap notes: 2018 Audi RS3 powertrain into a 2019 Golf R (US), supplied to MK7HQ (engine T91 wiring spreadsheet, wiring notes and RS3 seat wiring spreadsheet)
- YouTube build series: 2019 Golf R RS3 swap (transcript supplied to MK7HQ)
- Owner posts in the MQB Tuning and MQB Track Cars UK Facebook groups, September 2026: DQ500/DQ381 gearbox plug pinout (screenshots supplied to MK7HQ)