Love your C101!!!

[Fcknslo]

I can't thank you enough for this information. I'm in the process of switching the wiring harness and can't thank you enough for you taking your time and writing this up. this definitely needs to be stickied

[deansbimmer]

Thanks for posting this. It saved me some homework in my diagrams. Now, all we want from you is similar info on modding as S62 ecu! :D

[BeirBrennerE30]

Thanks for posting this. It saved me some homework in my diagrams. Now, all we want from you is similar info on modding as S62 ecu! :D

I could do that... but there are are over 100 pins and not 20 lol

[xLegendOZWest]

absolutely amazing! but i gotta ask. where is the year split between "early" and "Late" e30s. i mean obviously i figure anything with plastic bumpers is later, but what about the 88? (weren't there some differences between it and say an 86?)
i guess the reason i ask is because i never really knew where my car fit in when it came to wiring differences.

[redneckvtek]

just did this on my e30 (85 to 91 swap).. saved my life. Thanks!

IIRC, 86 and up got the round c101. before, square one.

[M3 euro ltw]

Hey guys, a quick question for you all.

I'm working hard on a plug and play system to drop S54's into older cars that I want to be as complete as possible. To be honest, the first harnesses I'm doing will be OBD-1 E36, but it will be a small jump to make a C101 instead of the X20... but here goes a question for the pro's

**************
Pin#4 – Br/Vi – Water temp – This is the signal wire for the e30 clusters water temp gauge. The e30 sensor should be grounded to the engine. The terminal on the sensor should be connected to a wire that connects directly to c101. From there it goes straight to the cluster temp gauge. This sensor is not used by the DME at all. For an accurate temp gauge the correct e30 temp sensor must be used.

************** Revised after getting the proper answer ******

Thanks to board members for the answers.

The sender for the E30 cluster is apparently grounded through the chassis which doesn't really yield what is considered an optimal set up for using coolant temperature for the DME's purposes of cold starts, temperature compensation etc....

For E30 customers I will be offering a trade in for their core coolant manifold, my machine shop will TIG weld on a very professionally done bung for the E30 cluster temp sender. We'll use the factory S54 coolant sensor which is the two wire version in the stock location, and we've calibrated those already to have a proper temperature/voltage table.

This will be relatively inexpensive, and unless directed to return the exact same manifold (ie, its pristine, you must have a pristine one back) I think I'll collect some, and have them ready to go, on the shelf as exchange items. Re-using the factory sender saves money too. I'll re-wire the harnesses to accomodate the E30 sender AND the S54 one. No biggie at this point.

Sorry for the WOB

Alex.

[lifeiskaos]

I suppose for the E30 crowd, I could use the sender for the cluster only, and split the signal to the DME, and adjust its table??????

(yuch, not appetizing)

Not a big fan of that... I'd use a DME coolant temp sensor (obd1 sensor would be fine) in the port in the head, then find somewhere else to put the gauge sensor... Although it has to be metal, so it has a ground...



Looking at that picture, I think I might put the gauge sensor #18 and the DME sensor to be in the #4 spot

That's a tough one.

[BeirBrennerE30]

Not a big fan of that... I'd use a DME coolant temp sensor (obd1 sensor would be fine) in the port in the head, then find somewhere else to put the gauge sensor... Although it has to be metal, so it has a ground...

[ATTACH]29368[/ATTACH]

Looking at that picture, I think I might put the gauge sensor #18 and the DME sensor to be in the #4 spot

That's a tough one.

DME sensor has to go at 18. DME needs an accurate signal for engine temp compensation before the thermostat opens

[M3 euro ltw]

Part #3 above

********** Edited *********
I've edited my prior one to thank people for help on my first question.

... and altered this one to pose a different question about the C101 and C104 issues that are more on topic to the thread.

**********

Does anyone have a part number for the engine harness side of the C104 connector and its correct pins?

**********

[JiXer]

On the unloader realy.... is it safe to assume that when swapping a 24v motor in, using an OBD1 e36 harness.... You can splice the Blk/Grn wire that goes to the starter directly to the Blk/Ylw starter wire?

Also, it seems that there are 2 tach signals going through the x20 connector, Pin 14 which is Blk/Blu and Pin 20 which is solid black. I believe pin 14 is supposed to connect to c104 and from what I can tell, pin 20 must connect directly to the cluter?

Can anyone confirm this?

[2mAn]

J, Im in the same boat as you. Im swapping a 84 to OBD 1 converted M52. I think you have it right. Pin 20 goes to the cluster and Pin 14 to the C104. Im using a OBD 1 E34 wiring harness so its not the exact same colorwise, but very similar ( my pin 14 is Black/ White)

[JiXer]

Yeah, Im mainly concerned about the unloader relay.

[nando]

Pin 14 is the VSS signal

Pin 17 is ABS feedback into the DME on the ix (engine brake torque reduction).

The only pin that is never used is 3.

[nando]

Pin 14 is the VSS signal

Pin 17 is ABS feedback into the DME on the ix (engine brake torque reduction).

The only pin that is never used is 3.

Thanks for posting this. It saved me some homework in my diagrams. Now, all we want from you is similar info on modding as S62 ecu! :D

The DME is pretty easy, and the wiring is pretty similar to the s54. :)

[thedivision]

Thanks for taking the time to do this, it's very helpful.