HELP e30 m3 s52 swap - Runs but - Coolant Temp Gauge not working... toltally stumped.

[maclogos]

You shouldnt have to cut that wire for it to work. I have a 2 prong connector and use the M20 single prong sensor. My gauge works fine after installing a new sensor. I dont have a S50 but i do have the M50 and im sure the plug for that sensor is the same. At least from the pic i saw it looks exactly like my plug.

[gath]

Bumping this back up. So the solution was to cut the ground (brw/ylw wire) at the connector?

[r4esh]

"328ijunkie" (Dave?) - You rock. You were right... I had just convinced myself that there was no way it was a duel wire plug. I could have sworn on our previous swap it was a single wire plug. Sure enough the gauge works. Ultimately I hope this thread serves anyone have an issue with their temp gauge as thanks to everyone's support that is pretty much every possible solution / troubleshooting suggestion here. Dave as soon as there spare gauge comes I'll just send it back / wont even open it. Thanks again for looking out, you guys rock!
Man... it feels good to safely drive my car knowing I'm not cooking the motor!

[328ijunkie]

Pics of a customers conversion harness for reference:



I remove the unnecessary ground from the harness completely all the way from here to the X20:




Jeez my hands are nasty.

[Mr.SWISS]

Do we not have anyone local that can go assist?1?

Fly me down I'll fix it.

[r4esh]

The temp sensor plug is 2 pin even though the e30 only uses one. Have you gotten your replacement sender in?

Well that settles it then. I haven't gotten it yet, I'm going to piece the intake back together tomorrow, if all works well ill send the replacement back right away. Thanks again for sending me one.

[328ijunkie]

The temp sensor plug is 2 pin even though the e30 only uses one. Have you gotten your replacement sender in?

[r4esh]

Okay.. Just to revive this for a moment in case someone else with the same issue stumbles upon it...

I finally got a chance to pull the intake. I indeed had the oil pressure wire plugged into the temp sensor... fixed that.. went through all other connections multiple times, and the ONLY left over connector was a "2 wire" plug... confusing no? I swear I quadruple checked everything. MY harness came from a 525i. Does anyone know if there is a variation for that connector instead of the single wire? I know its strange, but I went through it OVER and OVER and everything else matched the ETM and the DOHC wiki wiring with this connector being the only thing left over.

SO my solution (haven't put it all back together yet to test this) - I'm going to try the 2 wire plug. If it doesn't work I can a backup wire of my own from pin 4 to the sensor.

Either-way I will report back.

[Jalves619]

http://www.r3vlimited.com/board/showthread.php?t=230238

Oil light turns on after running for a while still? Look at post #4

[Jalves619]

Could dead SI batteries be causing issues? I've heard of them throwing off the tach and other gauges before. Since the temp gets power through the Service Interval Processor it seems possible. Have you checked for power at C5 Pin 1 and for a ground at C5 pin 12?

[Sputnik]

Forgive me if its already been covered, but have you check the resistance at the sensor to see if it was faulty from the beginning?

[r4esh]

New update. I have a new temp gauge on the way which I will install Monday and share result. Here's some more insight:



^ I know we all love reading ETMs... so I highlighted our focus in red. I'm not sure I understand this. Apparently the temp sensor goes right to the gauge. No fuze in between? Or is the whole cluster on a fuze? IT draws power from "service interval process" ? I was hoping this would give me some insight to other places to check for an issue, but it seems like the issue can only be "sensor, gauge, or wiring". I think we can rule out wiring at this point.

[DTM190]

Gotcha

[r4esh]

Out of curiosity why was this done instead of replacing the M50 gauge sensor with an M20 sensor?

You didn't read the whole post. This is an s52. So you must use the obd1 m20 sensor for my application. Just so you know.

[DTM190]

Yes it's an m20 sensor. And it was re-threaded by Market Motorworks to fit into the old throttle body coolant line hole on the block for the swap.

Out of curiosity why was this done instead of replacing the M50 gauge sensor with an M20 sensor?