M5x Looms
One of the trickiest parts of the M5x engine swap is the wiring. The mass of cables snaking their way around the engine bay is enough to put off even the most hardened of mechanics, which is why the Zone experts have put together the following tables. Just chop up your M5x loom and rewire it to the C101 engine plug of your E30.
The looms available to you are dependant on the donor vehicle. Looms from the E34 will have an ECU plug that reaches to the right side of the car, while the E36 loom goes to Near side of the vehicle. Note that the E30 side of the loom is also different depending on the age of the car, so match the age of your E30 to the appro
M50B25
| Pin # C101 | Colour | Goes to.. on E30 | Connect to Pin # M50B25 engine plug | |
|---|---|---|---|---|
| 1 | blue | pin 16 blue plug inst cluster - Charge light | 25 | blue |
| 2 | green/yellow | Pin 16 check panel - static oil level | 1 | blue/white |
| 3 | ||||
| 4 | brown | pin 26 blue plug inst cluster- temp gauge | 12 | brown/yellow |
| 5 | brown/green | pin 18 blue plug inst cluster- oil press light | 23 | brown/grey |
| 6 | green/white | Fuse 9 - Oxygen sensor relay | 22 | green/white |
| 7 | green | ign switch - switched power | 21 | green |
| 8 | white/black | pin 11 blue plug inst cluster- fuel rate input | 24 | white/black |
| 9 | black | pin 7 blue plug inst cluster- engine speed input | 20 | black |
| 10 | blue | pin 20 check panel- dynamic oil level | 2 | blue/yellow |
| 11 | white/green | pin 22 blue plug inst cluster- reset service lights | 19 | white/green |
| 12 | grey | Check Engine indicator | 8 | grey |
| 13 | green/purple | fuse 11- fuel pump relay | 13 | green/purple |
| 14 | black/white | pin 10 white plug inst cluster- speed signal out | 14 | black/white |
| 15 | black/green | pin 1 blue plug inst cluster- from unloader relay | 15 | black/green |
| 16 | white/black | Diagnostic connector pin 6 | 17 | white/purple |
| 17 | ||||
| 18 | black/yellow | ign switch- start | 18 | black/yellow |
| 19 | ||||
| 20 | red/yellow | ABS power | 3 | red/white |
M52B28
| Pin # C101 | Colour | Goes to.. on E30 | Connect to Pin # M52B28 engine plug | |
|---|---|---|---|---|
| 1 | blue | pin 16 blue plug inst cluster - Charge light | 25 | blue |
| 2 | blue/black | Pin 16 check panel - static oil level | if fitting oil level sensor, connect here | |
| 3 | ||||
| 4 | brown/purple | pin 26 blue plug inst cluster- temp gauge | 12 | brown/purple |
| 5 | black/brown | pin 18 blue plug inst cluster- oil press light | 23 | brown/green |
| 6 | green/yellow | Fuse 9- Oxygen sensor relay | 22 | green/white |
| 7 | green | ign switch - switched power | 21 | green |
| 8 | yellow/white | pin 11 blue plug inst cluster- fuel rate input | 24 | white/black |
| 9 | black | pin 7 blue plug inst cluster- engine speed input | 20 | black |
| 10 | purple/green | pin 20 check panel- dynamic oil level | if fitting oil level sensor, connect here | |
| 11 | white/blue | pin 22 blue plug inst cluster- reset service lights | 19 | white/green |
| 12 | ||||
| 13 | purple/red | fuse 11- fuel pump relay | 13 | green/purple |
| 14 | blue/yellow | pin 10 white plug inst cluster- speed signal out | not connected | |
| 15 | black/green | pin 1 blue plug inst cluster- from unloader relay | 15 | black/green |
| 16 | ||||
| 17 | ||||
| 18 | black/yellow | ign switch- start | 18 | black/yellow |
| 19 | ||||
| 20 | brown | pin 20 blue plug inst cluster- ground | not necessary to connect | |
NOTE: If using an oil level sender from an E34, then connect the blue/yellow wire to pin #10 C101 and the blue/white wire to pin#2 C101. Take the brown/black wire up to the wiring junction plastic box on the firewall where the engine loom connects to the ECU wiring and X20 plug and connect it into a brown or brown/black or brown/orange wire (all ground wires).
Comments
Unused Wires
Once you have cut up your M5x loom, you will see that several wires are not used. These are mainly associated with the Aircon. Rather than leave these wires floating, and possibly suseptable to static, it is recommended to connect them all to earth, via 1000 ohm resistors.
Econometer
When you fit the M50/52 and other motors to the E30, the economy gauge and OBC fuel consumption readout will go haywire due to the injector pulse duration differences between the M20 and M50/52 and S50 motors.
If you want to correct the gauge/OBC to read correctly, this fella in the USA sells this little electronic gizmo to correct it.
