Retrofit 'check engine' light into an early swapped car

[MattM]

Like the title says i want to do this, ive been reading the ETM's and it doesnt seem that difficult. I have a cluster from an 88 325is that is already in the car. All i need to do is connect the green wire pin 8(E34) from the X20 to the cluster... but where?!? The E30 ETM shows its a brown/blk wire, but leaves out the pin/connector that is goes through.

here is the E30 diagram:


and the E34 one:

[flyboyx]

the e30 wiring diagram above actually shows the check engine light going through pin 12 of the c101. since you have an early car, i have to assume this diagram doesn't match your vehicle and is worthless to you for this purpose. since i know if no wiring diagrams for the inside of a bmw instrument cluster, i suggest taking the cluster apart and doing this: trace the circuit board from where the cel light contacts are next to the hole . one will go to ground and the other terminates out the connector on the back of the cluster. ordinarily, you could tie into that corresponding wire in your harness, but since i doubt you have that wire, i would suggest getting creative a bit. just solder a wire inside your cluster somewhere on that contact and find a way to get it out the back. drill a small hole if you have to. i would cut a random single wire connector from under the dash of a parts car and put that in so you can remove your instrument cluster in the future without having to cut/resolder.

[Jean]

Check engine light doesn't go through the instrument cluster circuit board. The bulb is added from the back, one lead goes to the ECU/harness and one to switched power. Done.

[MattM]

looks like i need to order a bulb, i got it all wired in this morning, and it gives me a solid 12v with the ignition in run position, but i have no bulb.... darn.

[spiftacu1ar]

Resurrecting an old thread.

Im trying to do the same thing. Wiring makes sense, but does anybody know what bulb and bulb holder to use that will fit in a late model cluster?

It looks like the check engine light fits into a plastic slot (the blue plastic on the back of the cluster) that is not the same as all the other cluster bulbs (which twist onto the circuit board itself).

[36brua]

Resurrecting an old thread.

Im trying to do the same thing. Wiring makes sense, but does anybody know what bulb and bulb holder to use that will fit in a late model cluster?

It looks like the check engine light fits into a plastic slot (the blue plastic on the back of the cluster) that is not the same as all the other cluster bulbs (which twist onto the circuit board itself).

Correct bulb socket is push in. approx 5mm dia w/ small lamp .
easiest is to pull one from another cluster at jyard. There may be 1 or 2 on the late cluster. or contact someone that rebuilds clusters (R3v member gregs///m ? chk user name

wiring is straight forward find switched hot run find green/white under dash. ground through C101 to corresponding pin on new harness
I installed one on 86 cluster this way. GL

[M3PO]

I used a tiny LED and mounted it elsewhere. Super simple. Attach the CEL ground wire from the DME and switched power, mount it somewhere inconspicuous.

[spiftacu1ar]

Thanks. Gregs///m (Bavrest) didn't seem to know where I could find one. I can't find the part on realOEM.

I will probably just find a generic bulb holder of some sort and find a way to stick it in there, lol. I might try to find one next time I'm at a pick n pull, but I don't want to make a trip there just for bulb holders.