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I've noticed as I've been driving my car regularly the past few months that the temp gauge permanently hovers right around 170...obviously not accurate with a cold engine, and doubtful in summer stop and go traffic. Whats the best way to start trouble shooting to determine if I have a bad sending unit, bad gage, or a bad connection somewhere in between?
Turn the key on, take the wire from the top of the sensor and touch it to ground. The gauge should show full scale. With the wire disconnected and not grounded, the gauge should read full cold. That will tell you if the gauge and wiring are in the circuit and at least responding. Post back what happens and we can take the next step. Don't forget to turn the key off when you're done. (really sounds like at least one wire isn't connected to the gauge or the gauge is stuck or open.)
So as far as I can tell, the gauge is reading in the correct direction, just not accurately, or to the full sweep of the gauge. FWIW, while driving, the needle sits pretty much as shown in the first pic.
Because it is indicating high in the low temp direction and low in the high temp direction, it really acts like a bad gauge. A short or corroded connection would read high or low both ways. (If you feel pretty confident that you actually got the wire shorted to a GOOD ground for the high temp reading direction)
I used a jumper and shorted it directly to the negative post on the battery, so I think I'm good there...
Frustrating part is that I'm planning on eventually rewiring the entire car, along with a full gage cluster restoration, but its probably going to have to wait another year or so as I want to take my time, and do it correctly.
After fooling with mine for awhile I would second the suspicion of a bad gage. I would look around and see if you can find someone who can work on your existing gage because new gages I've ordered just don't match the original gages. Colors are off, width of graduations are whiter or wider, or needles have different center bezels. One guy who is local and rebuilds, restores gages is Joe Ray in North Little Rock. A lot of the guys on here recommended him and I've been over to his house that he works out of. He has a huge collection of gages and parts. If he couldn't get your gage working I would bet he could at least come up with a good used one that matches the original gage.
My temp gauge is a little sticky from being in a humid garage. I suppose the movement pivots get rusty. I tried the grounding trick and the gauge slammed well past the max temp, I don't think it liked that. It retuned to somewhere between 100 and 210. If I tap around the gauge it will slowly work its way to the low end. I'm hoping now that it's in a better temp/humidity controlled garage the gauge will slowly loosen up.
After fooling with mine for awhile I would second the suspicion of a bad gage. I would look around and see if you can find someone who can work on your existing gage because new gages I've ordered just don't match the original gages. Colors are off, width of graduations are whiter or wider, or needles have different center bezels. One guy who is local and rebuilds, restores gages is Joe Ray in North Little Rock. A lot of the guys on here recommended him and I've been over to his house that he works out of. He has a huge collection of gages and parts. If he couldn't get your gage working I would bet he could at least come up with a good used one that matches the original gage.
Agreed....no interest in a new gauge....I'll have the entire cluster restored at once, just didn't want to have to do it now
07-14-2020, 07:15 AM
Trouble shooting temp gage?
