link85x

iTrader: (1)

Hey everyone, got a problem. My coolant temp gauge doesn't work. I've been trying to pin-point the problem but no luck. The gages fuse isn't blown. One question is the green wire that plugs in the temp sensor in the cylinder, is i hot on Key on engine off? It should be correct? If it is, i don't have any power at the wire where it meets the sensor. Could the wire be possible broken before C100 or after? Could the gauge itself be faulty?

chevycamaro91

iTrader: (1)

check your thermostat make sure its not sticking.

FYRCHKN

I had the same problem on my 79 T/A. I replaced the sensor ($5 or so) and everything started working properly. My car was running at normal temp (not overheating) and the guage was pegged out.

spr250

the sensor is basically a thermo variable resistor, the hotter the temp the more resistence and once it gets hot enough it will open the circuit. So I would try that replacement, also find where the wire goes to and do a continuity check between the ends for a broken or shorted wire. If those are good, start troubleshooting any components that are connectec to it and continuity check for the wires between.

BigBadLou

iTrader: (3)

The sensor resistance drops with increasing temperature.
So you can test your gauge like this:
- unplug the green wire from the sensor in the driver side head - with the key on, the gauge should read full left (cold)
- now ground the green wire - with the key on, the gauge should read full right (hot)
- you can optionally put a 135ohm resistor on the green wire (against ground) and the gauge should point up (cca 220 degrees)

If these tests pass, it would point to a faulty sensor.

Hope this helps.
Lou

spr250

Oops sorry about the temp/resistence, wasnt paying attention.must have been also thinking of the temp switch, And BBLou has it right. After I read it again I confused myself, I need to get more sleep.

spr250

Also your gauge could be bad, I just got back from spending some time as a generator mechanic for the Army in Iraq, our gauges went out mostly due to voltage spikes, dirt, moisture and hot*** temps. Trust me, 150* plus sucks. Anyway, a repair manual should have the ohm readings for testing. Personally I would replace it anyway if it came down to opening the console. Heck, update the dash the youd like to have.