temp gauge spikes to the top - PeachParts Mercedes-Benz Forum

crhenkel · #1 09-17-2007, 11:15 PM

I have a problem with my water temp gauge in my 1993 2.6 190E. It is usally pegged at the top of the gauge while the water temp is typically right where it should be. The gauge or the sensor is malfunctioning. I compared the resistance readings from the suspect gauge with another temp gauge from a different cluster I have and the readings are the same. I replace the temp sender and it did not help. Any ideas what to do next?

Arthur Dalton · #2 09-17-2007, 11:38 PM

There are 3 temp sensors.........did you change the single wire one?

If you substitute a 38 ohm resistor for the sender , the gauge should read 100C..if not, the gauge is bad.

crhenkel · #3 09-18-2007, 12:35 AM

I'll grab a resistor and test it out. Any idea what the color bands are for a 38 ohm resister? I can figure it out after a while if I need to.

Arthur Dalton · #4 09-18-2007, 10:57 AM

Just get a 100 ohm wire-wound adjustable and set it with your ohm meter.

crhenkel · #5 09-18-2007, 11:38 AM

Ah,
good idea, for a minute I was confused, but I get it. I variable 100 ohm pot and dial it in to 38 by using my meter. Got it. Great idea, I had not thought of it, but I wish I had. Common sense was out to lunch.
I'll pick one up at Radio shack today.

Arthur Dalton · #6 09-18-2007, 11:44 AM

That way you can test the guage throughout it's entire Range.
I have a 38 ohm made up for my toolbox with a ground clip for fast testing.

Here are the specs for the sensor with the gauge reading at each value

OHM 110 = 60C
67 = 80C
38 = 100C

david s poole · #7 09-18-2007, 12:00 PM

i have found problems with the ground on instrument panel causing such a problem and fixed it by making a ground wire one end under instrument panel screw and other at main ground behind instr panel.

david s poole · #8 09-18-2007, 12:02 PM

p.s. very unusual to find bad gauge.

crhenkel · #9 09-18-2007, 12:40 PM

David,
Thanks, I was thinking I have not found many bad gauges either and I convert a lot of gauges to white faces so I see them alot. I will check in to the ground issue and get a test setup to check the gague, thanks for the advice.

4wheeling · #10 09-19-2007, 12:30 PM

I have the same problem with my 1994 E420. It spikes to it max range and gets stuck there. Are the resistor values the same for my car as well? Thanks.