E30-M10 to M20 Cluster wiring help please!

[84E30M20]

Hey guys, I traded my old car for this 1984 318 E30, it has a complete M20 swap in it, but the guy didnt finish all of the wiring,

Everything else works, except the turn signals, and the tach / speedo / fuel gauge / pretty much nothing but the battery light works on the cluster.

I have been driving it around without those things not working, but im a gauge watcher, i want to see how much fuel i have and how fast im going / revving it up and any other needels / lights that pop up

I have picked up the Haynes Manual for the BMW 3 - 5 series it says that both models are covered there..

My question is...
Do all of the harnesses use the same colors for each specific thing? I.E. tach uses the same color on all harnesses? or the speedo?

The repair manual I have doesnt go into the specifics per model.. it just has the basic wiring diagrams, from the book all the wiring colors are the same. it doesnt have different layouts per vehicle... is that the case ?

I have the ECU pinout, but i was told that you cannot directly wire the Cluster from the wires coming from the ECU that you have to go from the wires coming out of the fusebox, so the ecu pinout doesnt seem to help me much... i had planned to go pin for pin and wire everything up,

The ECU is under the dash on the passenger side, it goes from there outside into the firewall/fusebox that is inside of the engine bay on the drivers side, then it comes down into the cabin, and its a big wad of wires tucked away under the dash there....

The Wiring from the Firewall forward is from the 325i, and the rest is the original body harness from the 318.

The original car is a 84 318i -
The swap came from a 89 325i.....

Info about the ECU/Engine-
325i
M20B25 (170hp)
87-91
Bosch Motronic M1.3 - 0 261 200 525

I have looked all over and found nothing but wiring info for other swaps and stuff, any info you can give me would be greatly appreciated!

[jlevie]

The Haynes (or Bentley) probably is going to be of little help in figuring this out. You need the ETM for the 84 318 and for an 89 325i. You'll have to pretty much work it out pin-to-pin. The ETM's can be found at http://wedophones.com/BMWManualsLead.htm

[84E30M20]

thanks for the fast reply,
i have downloaded the ETM that was from the 325e / 318i as suggested in one of the posts where another guy asked about wiring.

i was going through that one and i was unsure about what the letters after the model were, so i didnt want to take a chance with hooking the wrong ones up

i wasnt sure what the difference between the 325 I / E / IS / IX etc were,

thank you so much for that website im going to go print off the exact ones that i need and see what i can decypher!

[84E30M20]

Another question:

Can i keep the 318 cluster or do i need to swap it with one from a 325? i believe thats what the guy has in it, will it make a difference that the 318 cluster is a 4cyl and the 325 is a 6?

I was wondering if this would throw the Tach / speed odometer off.. not sure if they are configured to each specific engine, i havent found anything to tell me one way or the other.

[mcgrath]

changing the engine should not have effected the cluster in anyway other then maybe the tach. If you still have a service indicator board in the cluster, check the batteries. chances are everything is corroded up and will need the batteries removed and contacts cleaned. you should be able to just plug in a 325i cluster and it function properly.

[84E30M20]

Thanks, i have not had a chance to wire in any of the gauges, i printed off all of the info i needed from the ETM and i was making a list of what wires would need to be connected together, the guy that did the swap just left a huge bundle of wires laying in the floor, i wanted to get as much information about the wiring before i acctually go out and attempt it, This has been my daily driver and i dont want to mess anything up by accidentally crossing wires :)

I just was not sure if i should make the effort to hook up the tach in the cluster or use an aftermarket one.. i have one laying around that im not using on anything else so i may just do that,

I need to go double check to see if the cluster is the original 318 cluster or if it is the one from the 325.... I traded for this car, after the swap was completed and i didnt get to ask the guy a whole bunch of questions about it before i did the trade.

[84E30M20]

I went outside and ran through the various wires, it seemed fairly straight forward, just following the 2 diagrams and linking them together,

until... i came across a few wires that had multiples of the same colors, this might be a stupid question but im just making sure,

It looks like the multiples are just power wires that run to the different fuses, i was wondering if it makes a difference if i just connect the wires to the corresponding colors, or do they have to be put to the specific ones perfectly? it seems like the Fuse for the tach / fuel economy gauge / brake warning system etc, are all the same color wires coming from the fuse box...

I was just double checking before i wire them up, they seem to all be going to the same spot, so connecting them to different ones without knowing which one they originally went to will not make a difference will it?