Firstfives.org

Hi e12 friends!

I have two questions I am hoping the community can help me out with. I have a 1981 528i that I picked up last December, it's a lovely car 5speed with very little rust and a great interior. I've been slowly fixing the little things that have gone wrong over the years and ran into a bit of a conundrum recently.

1) Temp gauge not working properly: It only barely moves, just a tiny bit above the blue cold range, even when the engine is fully warmed up. I changed the thermostat thinking it was stuck open but that made absolutely no difference. I found an article in the FAQ about the temp sensors,http://www.firstfives.org/faq/sensors/c ... nsors.html from that I think I need a water temp sensor. Is that sensor located on the thermostat housing, if so,which one is it ?


Also, the beige plug looking thing at the bottom of the picture, what is it, it looks like there should be something connected to it but there aren't any loose wires in the engine bay.

2:Rear door power window switch not working.Ok hear me out of this one...
The power window works from the master switch on the drivers door, but the switch on the rear door is inoperative. I bought a replacement switch off ebay thinking it would be an easy fix, swap out the switches and I'd be good to go. This isn't the case, the new switch makes no difference. I am fairly certain I have it wired properly, a gentleman on the facebook e12 group was kind enough to send me a picture for reference. Also the aforementioned master switch works,so current is flowing. Any suggestion on how to troubleshoot this?




Here's a picture of the e12 next to my M3

The gauge temp sender is the one with a single male terminal sticking up. On troubleshooting the P/W, I'd compare readings with the other side to see what's happening. If you need I can scan the wiring diagram, I thought I could find it online but I can't.

Plz see my tech article on dismantling and cleaning window switches from a few weeks ago. Pop the bezel off and clean it up inside. Keep defective switches for parts. There are 2 ball point pen springs in there that need to push the white things freely. Grease a bit after cleaning and touch up the contacts with a dremel or a file Not too much.

Test the temp GAUGE by removing the lead from the sender and touching it to ground. Have someone watch inside the car. If it pegs to total hot it's the sensor. If it barely moves you need to check the wiring to the gauge and possibly need a gauge. I have a few of them.

Good luck!

BTW a sensor is a $20 part i recall.

Toss in a new oil sender as well, they leak eventually.

Do you have a " child proof" switch in the center of the master panel switch? I forget.

n/m

I'm also interested in qu. 2 - what is that beige plug front of the motor? It runs to a sensor on the crankshaft so I'm guessing it's just for diagnostics, for some BMWs-specific tools maybe?

Lock wrote:I'm also interested in qu. 2 - what is that beige plug front of the motor? It runs to a sensor on the crankshaft so I'm guessing it's just for diagnostics, for some BMWs-specific tools maybe?

Exactly, a dealer only tool that likely hasn't been seen at dealers since the early 80s, if then.

GripGreg wrote:Do you have a " child proof" switch in the center of the master panel switch? I forget.

Yes...and that was the cause of my rear window switch not working. Felt a bit like an idiot for not realizing myself.

Thank you all so much for your replies and advice! I ordered a new sensor and put it in tonight.



and it work! I have a gauge now



It reads a little bit on the warm side but I think I just need to bleed the cooling system a bit better. I didn't bleed it after swapping out the sensor

Now to figure out what to use for a vapor barrier, I may just cut a piece of heavy duty trash bag and glue it in place unless anyone has a better suggestion

For the door? Visqueen!

Mike W. wrote: Exactly, a dealer only tool that likely hasn't been seen at dealers since the early 80s, if then.

Figured as much, that plug is unlike anything else in the engine bay.

Also I just cut trash bags to shape to seal the doors, I figure I'll need to get back in soon enough.