Temperature gauge problem

[Scottjeffrey]

 

After removing the instrument cluster to replace bulbs, upon reinstallation the temperature gauge failed to work. Between removal and replacement, I also installed a 320i alternator if that could be relevant.  I replaced the temperature sensor as it was very inexpensive first. Grounding its terminal produces no movement at the gauge. I swapped in a ‘new’ used gauge and still nothing. When I turn the key to the on position, the gauge moves a hair only. The printed circuit board looks perfect without any signs of corrosion or damage and all other components in the instrument cluster (fuel gauge, lights etc are working fine. After writing this I went back out and hooked everything up again. Had nothing at the gauge but while wiggling the connections while all were hooked up, the gauge sprang to life. Instead of leaving it alone, lol, the thought occurred to me that perhaps the reading can't be trusted if there is improper resistance to to a problematic connection. I also don't know if it came on due to something making contact (and then losing it again inside the cluster involving the PC board rather than the external connectors. Used some de oxit on all external connections but again nothing from the gauge even when I tried jiggling at the connections. Any wisdom on the situation and how I might proceed? Is there a way to check the 'internal connections/printed circuit board with my multi meter while it out?  Thanks again--Scott

Edited February 16, 2019 by Scottjeffrey

[adawil2002]

Could be the the pins on the big black plug need to be cleaned. Though it appears you cleaned everything.

 

If the car is cold, there won't be any movement on the temp gauge at all. Do you have an extra ground on the two knurled brass nuts on the back of the Fuel/Temp gauge?

 

Looks like this U__U____________U  Making up a harness is pretty easy, it's a bit of insurance against bouncing Fuel & Temp needles.

[M3M3]

If you swapped gauges and it didn't work, then the issue is in the wire between the cluster and the sensor.  Have you done a continuity check on it?

[Scottjeffrey]

Hi Andrew, I do have the extra grounding the way you suggest. I am wondering about the black plug and its connection (male part) on the board. I couldn't get it to work after wiggling it a second time so the problem seems to me to be there or elsewhere inside. Hi Marshall, I figure I must have continuity from the sensor to the plug if the wiggling made it work, at least temporarily when it did? I have removed the cluster and later will clean the insides with electrical connection cleaner as well as the external plug itself. A bit stumped yet but will fiddle around later. I am hoping my circuit board is ok, not wanting to spend more money.

Thanks too you both and any more suggestions are appreciated.

Scott

[02Les]

Try putting your old sensor back in, I have had a new one that was useless right out of the box.