Engine temperature gauge has no power to sending unit.

[CDLong]

I would use a battery as we all have one of them around.

I dont have a bench top power supply but if you do and it puts out 12 volts then that can be used for testing.

If me I think I would put power to the IVR as we know that works as the other 2 gauges work.

Then test that power (blinking) out of the IVR to the temp gauge input is good and then the output of the gauge.

If you have power in & out of the gauge you will need to trace the board out of the gauge to the plug as it has to be failing some where?

If that checks out then you will need to test the wire from the plug to the sender in the engine bay as it may be open.

Dave ----

Thanks Dave, I was told that because my other gauges work, it's probably in the wiring.

 

[CDLong]

Be careful as the gauges are really 6v gauges, as Jim said. The ICVR just chops the voltage until the average is about 6v, and since it is really just feeding a heating element in the gauge the chopped DC doesn't matter.

But if you put 12v to the gauge you could burn out the heating element. And it'll peg in a hurry. In my testing 5.4V pure DC is about right to bring the gauges to the top mark.

I guess I could use a 6-volt lantern battery? Gary, what do you use to obtain 5.4 volts?

 

[Gary Lewis]

Be careful as the gauges are really 6v gauges, as Jim said. The ICVR just chops the voltage until the average is about 6v, and since it is really just feeding a heating element in the gauge the chopped DC doesn't matter.

But if you put 12v to the gauge you could burn out the heating element. And it'll peg in a hurry. In my testing 5.4V pure DC is about right to bring the gauges to the top mark.

I guess I could use a 6-volt lantern battery? Gary, what do you use to obtain 5.4 volts?

I use a lab power supply that is adjustable. But you could use a 6v battery for testing. However, you really shouldn't need to do that. As has been explained, if you put a test light where the sending unit is you should see the light flash if the wiring is good. (The flashing is because the ICVR is just a chopper, not a voltage regulator.

And if it is flashing then grounding the wire should send the gauge to full scale pretty quickly when the key is on.

I replaced the wonky ICVR with an adjustable voltage regulator, as you can see on the page at Documentation/Electrical/ICVR. However, if your other gauges are working correctly then it isn't the ICVR.

[CDLong]

I use a lab power supply that is adjustable. But you could use a 6v battery for testing. However, you really shouldn't need to do that. As has been explained, if you put a test light where the sending unit is you should see the light flash if the wiring is good. (The flashing is because the ICVR is just a chopper, not a voltage regulator.

And if it is flashing then grounding the wire should send the gauge to full scale pretty quickly when the key is on.

I replaced the wonky ICVR with an adjustable voltage regulator, as you can see on the page at Documentation/Electrical/ICVR. However, if your other gauges are working correctly then it isn't the ICVR.

I'm don't have a lot of electrical knowledge. The cluster is out of the truck, I need to replace the shift. Could I put 12 volts DC to the red & white wire in the plug that attaches to the cluster and check the connector that attaches to the sending unit for 12V?

[Gary Lewis]

I use a lab power supply that is adjustable. But you could use a 6v battery for testing. However, you really shouldn't need to do that. As has been explained, if you put a test light where the sending unit is you should see the light flash if the wiring is good. (The flashing is because the ICVR is just a chopper, not a voltage regulator.

And if it is flashing then grounding the wire should send the gauge to full scale pretty quickly when the key is on.

I replaced the wonky ICVR with an adjustable voltage regulator, as you can see on the page at Documentation/Electrical/ICVR. However, if your other gauges are working correctly then it isn't the ICVR.

I'm don't have a lot of electrical knowledge. The cluster is out of the truck, I need to replace the shift. Could I put 12 volts DC to the red & white wire in the plug that attaches to the cluster and check the connector that attaches to the sending unit for 12V?

If I understand what you are asking, then yes. I think you are saying that you'll put 12v on the R/W wire in the dash at C208A, with the cluster disconnected, and check at the sending unit for 12v. That will work. BUT, make sure the wire isn't on the sending unit your may mess it up.

[ArdWrknTrk]

If I understand what you are asking, then yes. I think you are saying that you'll put 12v on the R/W wire in the dash at C208A, with the cluster disconnected, and check at the sending unit for 12v. That will work. BUT, make sure the wire isn't on the sending unit your may mess it up.

Would probably be better to indicate resistance than voltage, as that's what the gauge is doing.

 

[Gary Lewis]

Would probably be better to indicate resistance than voltage, as that's what the gauge is doing.

Right. It would be easy to put the connector on the sender and read from the red/white wire to ground. The sender should be between 12 and 72 ohms, and probably close to 72.

[CDLong]

If I understand what you are asking, then yes. I think you are saying that you'll put 12v on the R/W wire in the dash at C208A, with the cluster disconnected, and check at the sending unit for 12v. That will work. BUT, make sure the wire isn't on the sending unit your may mess it up.

https://forum.garysgaragemahal.com/file/n142938/pg-98-with-gauge-circuit-error_orig.jpg

Yes, you understood me correctly, but I will be checking the resistance as Jim has suggested.

[CDLong]

Would probably be better to indicate resistance than voltage, as that's what the gauge is doing.

Thanks Jim, I'll check the resistance in the wire.

[CDLong]

Right. It would be easy to put the connector on the sender and read from the red/white wire to ground. The sender should be between 12 and 72 ohms, and probably close to 72.

Thanks Gary. even I can understand how to do this.