Temp gauge not working on 93 Suburban 5.7L

[Donald]

The temp gauge on my old 93 Suburban with a 5.7L engine stays in the below cold. Basically it never moves, yet I am sure the engine is heating up fine. I pulled the connector off the sender and reseated it, no change. I pulled the connector off and shorted across across it and the gauge did not move. I assume the sender just changes resistance from very high at cold to very low at hot (or thats the way it is in my boat with a 5.7L).

Maybe its more complex than I thought?

I still would guess its the sender.

Does the computer in this car use the temp from the sender to adjust things, or is the temp just reported on the gauge?

 

[daman]

If you grounded the temp senders wire to chassis ground it should have forced it way over to hot,if not you got cluster problems(connection?) or wire problem somewhere.

that truck has a ECM temp sender in the intake(yellow/black wires) that tells the computer how hot the engine is,it's separate from the gage/light circuit.

 

[bullwinkle]

There's 2 different senders, sounds like you got the correct one (only 1 wire, the ECM has 2), if your other gauges all work it's a bad gauge or wiring. I'd put an aftermarket one on-the factory ones are pretty inaccurate even when they're working!

 

[Donald]

I am trying to figure out where the one with 1 wire is. I do not see it on the intake manifold. Is it on the radiator? But that would not make sense, you want the engine temp, regardless of what the radiator is.

 

[daman]

Originally Posted By: Donald
I am trying to figure out where the one with 1 wire is. I do not see it on the intake manifold. Is it on the radiator? But that would not make sense, you want the engine temp, regardless of what the radiator is.

the single wire for the gage is on the driver side sensors in the head,it's green wire,it is not in the intake,the one in the intake is a two wire like i posted above for the ECM

 

[mechtech2]

daman has it covered well.

 

[Donald]

I found it, have a new sensor if needed and am waiting for someone to watch gauge while I short out the connector at the sensor wire. Where is the wife when you need her??

 

[daman]

Originally Posted By: Donald
I found it, have a new sensor if needed and am waiting for someone to watch gauge while I short out the connector at the sensor wire. Where is the wife when you need her??

I use a wire,paper clip,alligator clip anything you got laying around..

 

[Donald]

I shorted it and temp gauge went to full hot, so sender was bad. Screwed in new sender but the conector did not fit right. After a little bit of looking, I discovered the plastic connector that is part of the sender had broken free and was still attached to the connector for the wire. Pulled it free and the connectors fit fine.

But then the car ran so bad I could hardly drive it. My guess was I had forgotten to plug back the ECM connector into the ECM sender and that was it. Ran fine after that.

When the ECM sender was not connected, the "service engine soon" light came on which in recent cars is change your oil. I guess back in 1993, the service engine soon light is the CEL.