"Jumpy" Gauge Needles

[1986 190E 2.3-16V]

A problem arose this past weekend with my water temp and fuel gauges. Upon startup and idle, the water temp and fuel gauges register fine. However, under acceleration and on the freeway, the water temp gauge will start rapidly jumping back and forth (about 25% deflection either side of ambient op temp). The fuel gauge did the same thing on a couple occasions on the freeway WEIRD! Could it be the sending units going bad?

Thanks for any insight.

Brian

[Benzmac]

IF it is more than one, I'd suspect a bad or loose ground in the cluster or where the ground bolts on to the chasis.

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Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Benzmac:

The chassis ground point(s) you speak of, is one of them near the front headlights? I did install Euro headlights the other weekend and noticed a group of brown wires connecting to a stud. Is it possible that I pinched a couple while installing the headlight(s)? I don't remember having to "juggle" those wires when installing the lights, but looking back I think they might have been routed near the headlight opening.

Just checked a schematic printout from my W201 CD (bought from you folks ) -- says that the fuel gauge and water temp gauge are wired together and have a 0.5mm brown wire as ground. It terminates to W1 (R14) "main ground behind instrument cluster via blower motor resistance group". I never touched the instrument cluster (honest). Could this instrument cluster ground continue on to the chassis ground? Or, does it terminate at the cluster? I have to bring the car in to repair the odometer/tripmeter anyways, so "they" should be able to troubleshoot/repair this "jumpy needle" syndrome, right?

Thanks for any additional insight(s)!

Brian