Temp Gauge

[Bsharp1223]

Hello. Was hoping for some insight. My temp gauge doesn’t seem to be working after My son and I have been working on our 2003 z71 Tahoe. Replaced the oil pan gasket. We dropped the steering center link to get the front diff back in. While we were there, we replaced idler and pitman arms. Had steering wheel secured during the pitman arm replace but somehow broke the clock spring and air bag light is on. Air bag light not the reason for post but just wanted to include most recent history.

Noticing the temp gauge never moves up from starting position. Replaced engine cooling temp sensor but still nothing on the gauge. Would a bad sensor or bad wiring harness pigtail cause a check engine light? There is no CEL on.

The gauge cluster is a little “moody” but I’ve never had this issue out of it. Is it possible maybe the gauge cluster just coincidentally started having that issue right when we were doing repairs? I’m worried about driving it because I don’t want to overheat anything but at a loss. Thanks

 

[OR VietVet]

Yes, could be coincidence. You said, "cooling temp sensor". Sensor is for engine/computer. Sender is for gauge. What is the location of the one you replaced? Could also be the pigtail.

 

[OR VietVet]

If you unplug the pigtail and ground the connector and the gauge pegs full hot, that means the pigtail should be good and the sender is likely bad. If does not peg, it could be gauge.

The sender will be on side of d/s head at front. Battery cables in way.

 

[Bsharp1223]

Yes, could be coincidence. You said, "cooling temp sensor". Sensor is for engine/computer. Sender is for gauge. What is the location of the one you replaced? Could also be the pigtail.

Yeah I guess not 100% sure on the terminology. It was on the right side of the engine. Sort of below where the alternator is mounted

 

[OR VietVet]

Do you mean right side as the driver's side? That is the left side. Side of vehicle is always referenced by when you sit behind steering wheel.

 

[Bsharp1223]

I think I’ve been standing in the front of that engine bay long enough that it’s affected my sense of direction! Drivers side is what I meant. So the left side.

 

[OR VietVet]

Left side front side of head, is the sender location. Try the pigtail ground test to see if gauge pegs. Plus, if you have a infra red temp gun you can see what the temp is at the sender area and at the thermostat area.

 

[Bsharp1223]

I’ll see what I can find out tomorrow. Thanks for the info

 

[Fless]

You can see what the sender is reporting to the computer by checking it with a scan tool in live data.

 

[Pete315]

I also have temp gauge not moving off 160. I removed the plug from the 2 prong temp sender. Question, how do you ground out the pigtail? I used my test light and with key in on position, I have no power on the gray wire. I used a paper clip and stuck it into each terminal of pigtail. I figured that would ground out the circuit which would cause temp needle to go way past 260 but needle did not leave 160. Should I have power going to sender? How can I tell if temp gauge in cluster is the problem. Thanks.

 

[strutaeng]

I also have temp gauge not moving off 160. I removed the plug from the 2 prong temp sender. Question, how do you ground out the pigtail? I used my test light and with key in on position, I have no power on the gray wire. I used a paper clip and stuck it into each terminal of pigtail. I figured that would ground out the circuit which would cause temp needle to go way past 260 but needle did not leave 160. Should I have power going to sender? How can I tell if temp gauge in cluster is the problem. Thanks.

Isn't that plug a 2-prong connector? I replaced it it on my 06 Suburban a few months ago because my pigtail connector tab broke.

I'm pretty sure the 2 prong sensors are just a resistance type. You can probably find resistance values online somewhere. I know the Haynes Manual has a table for these. Simply check resistance with a DVOM, probably with a cold engine so you know what temperature the sender should be reporting (in ohms.)

You can hook up a scanner that has live data to see what the ECU is reporting, then compare it to the instrument cluster gauge. Sometimes the clusters get taken apart to replace bulbs or stepper motors and the needles get reinstalled a bit off. Something to consider if you don't know the history on the vehicle.

 

[Pete315]

I do have the 2 prong sensor. My 81 Corvette had a 1 prong sensor. I know the Corvette would send the different resistance to the gauge from this 1 prong temp sender as the car warmed up. But with 2 prongs and 2 different color wires, I thought one wire would be power, maybe not a full 12 volts and the black wire ground would return the gauge with the resistance change. I could be wrong.