OK i have a 85 z-28 tpi and i cant get the water temp gauge to work. Well actualy it is pegged out all the way at the top and it never moves unless i unhook the actual gauge. Anyone know what might be wrong? Also someone told me i might need to ground it. if so can u plz tell me how. Thnx

Make sure there's a green wire attached to the sensor/sender in the drivers side head between the 1 & 3 exhaust port.

If it looks alright, try grounding the wire to see if the gauge dropps to 0, if it does, replace the temp sensor/sender. If it doesn't, somewhere between that wire & the gauge , the circuit is broken (open).

Actually, the gauge reads full scale when the green wire is grounded. If you remove the green wire from the gauge temperature sensor between cyl 1 & 3 and the gauge goes to the "100" mark (low scale), then the sensor is defective. If the gauge stays @ full scale, after removing the wire from the sensor, then there is most likely a short from the green wire to chassis ground somewhere.

.. guess I'm thinking bass-ackwards today...
my bad...

DB, correct me if I am wrong but I believe grounding the sender wire will peg the meter. If I remember correctly one end of the guage goes to 12 volts, the other end to the sender. A thermistor inside the sender changes resistance as coolant temp changes and provides a varying resistance to ground through the block moving the guage. If he is pegging, I would guess the sender wire is shorted possibly it touched the exhaust manifold. A VERY common problem with these guages is that when you first start it always does a full swing. Mine failed and it stayed pegged. Tapping it would sometimes get it to come back down.

Nope.. like I says above.. I'm just thinking backwards today apparently

I do actually know how it works but, apparently... well... not today

I had the same problem. My temp guage was stuck. Simply take the clear lens off of your gauges and push the needle back with your finger. You may want to bend the needle up slightly

i have the problem of the gauge always pegging out upon cranking the engine, its really pissing me off, Id like to put my cluster face lense back on, but i have to leave it off because i have to manually move the needle off the high side every single time i start the car, and my tach sticks at about 2200 rpm after cranking over for quite a while.,,

wth causes this temp gauge problem in these cars ? i unplugged the green wire running up the column, and thats appraently not the right wire, the needle still jams past H

good luck and thanks

It is designed to work this way. Same reason the engine temp lights on cranking. It is to let you know it is working. The problem with these guages is that the needle shaft goes through the plastic housing, just a metal pin through plastic(no bearing etc.) and it starts to bind. I had this problem and I tried to put a stop pin at the top of the range, did not work. The needle shaft was just too tight. I suppose I could have messed around some more but I felt it was better just to replace it. Considering the work to pull the instrument cluster 40 bucks for a new guage was a better deal. If you have the standard dash the GMSPO# is 25034460. We just have to face it, these cars are getting OLD.

so it means gauge is worn out ? i suppose my 84 S/E im cutting up is not a donor candidate for temp gauge ?

hmmmmm...

thanks!