temperature - gauge vs ecu data, same sensor?

[Reluctanse]

My temp gauge reads low, from where I think it should. Hooked up my bluetooth dongle and app to confirm, ecu temp reads higher than the gauge "seems".

could be the gauge motor, but I'm wondering - I know the older trucks have a dedicated sensor for the coolant temp gauge vs the ecu's sensor, does this truck also have a sensor just for the gauge? might swap that out before chasing the gauge cluster, let me know-

Oops - truck is a 2000 K3500 with the 7.4

 

[Supercharged111]

This is 180 in my 1500. Gauge and PCM have separate sensors. Gauge's is in driver's head.

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[someotherguy]

OP's 2000 carryover model may have some differences most of us are not used to seeing. The last few years of GMT400's are a bit unique in a few areas, and one of those are temperature sensors. Like my '96 C3500 had three temp sensors - one in the intake for the PCM data, one in the driver side head for the dash gauge, and one on the passenger side head for the auxiliary fan. I think it was @454cid that mentioned his later truck doesn't have all three of them; the aux fan may be PCM-controlled?

At any rate OP, just look around on your engine. The three locations I mentioned are where you're looking. On a "normal" (most GMT400's) setup, the dash gauge temperature sensor is between cylinders 1 and 3 on the driver side head. Yours almost surely has one there.. but it's worth looking just to be 100% sure.

Richard

 

[stutaeng]

This is 180 in my 1500. Gauge and PCM have separate sensors. Gauge's is in driver's head.

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That's what mine reads when ECU is correctly saying 190F. 2000 K3500 5.7. I just live with it.

I thought this only affected the SBC? I never understood why they had 2 temperature senders and they are not interconnected to each other to being with?

 

[Reluctanse]

thanks... i'll check and see, probably wouldn't hurt to replace it. EDIT: i supposed I could also get the multimeter out and test it before spending $$-

Funny anecdote speaking of multiple temp sensors... my 88 Supra has 5!!
-ecu temp
-gauge sender
-aux fan
-cold start injector
-a/c aux fan

 

[stutaeng]

I chased my tail trying to "fix the problem" on mine: https://www.gmt400.com/threads/overheating-after-changing-temperature-sender.48791/

What probably happened is I had never paid attention that my guage didn't go the halfway mark as my other trucks (I hadn't owned the truck for that long,) then I was thinking my sender was the problem after installing the wrong sender and thinking it was overheating (it wasn't)...

 

[454cid]

I think it was @454cid that mentioned his later truck doesn't have all three of them; the aux fan may be PCM-controlled?

Yes, My 99 doesn't have the 3rd sensor on the passenger side for the fan. I assume it's the PCM that turns it on. It's supposed to be either coolant of 225F (I think) or excessive AC head pressure (no idea on that number).