testing fuel temp and oil pressure left side cluster - PeachParts Mercedes-Benz Forum

samboyellowsub · #1 09-06-2012, 08:41 PM

I'm wanting to test a left section of a 123 instrument cluster so I pulled out an entire instrument cluster unit in a working vehicle and plugged up the test piece to its harness and I'm not sure that if this is a proper way to test it or if it needs to be attached fully in order to determine if it works.
The reason I ask is that I now notice two metal tabs on the right edge of that piece that look like they hook up electrically to the middle (speedo) section.

Without hooking it up fully, the temp gauge does move but it maxes out when I put on the brights, and the fuel gauge goes up to "full" position when I start the car (i don't recall what oil pressure gauge did). I remember it working when it was taken out but it's been in a storage room bouncing around for a few years. Nothing is broken or bent so I think it's been alright but just want to make sure.

Anyone with a super keen sense of the electronics on the car would be of great help.

Or if you know a way to test it with a multimeter.
Thanks

Biodiesel300TD · #2 09-06-2012, 10:37 PM

That cluster is grounded through the circuit board where it overlaps the other gauges. Best to remove your old one and put it in the cluster and plugs it in.

samboyellowsub · #3 09-07-2012, 01:04 AM

Quote:

Originally Posted by Biodiesel300TD

That cluster is grounded through the circuit board where it overlaps the other gauges. Best to remove your old one and put it in the cluster and plugs it in.

Thanks for that info. I could also just ground it with alligator clips. I'm trying to avoid taking the steering wheel off and properly installing the test piece in order to test it.

Thanks.