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randyc · Joined: 29 Feb 2004 Posts: 24 Location: Florence SC

The temperature gauge in my 2000 Pete recently quit working. I had my regulators replaced thinking that they were stuck wide open. Whenever I got my truck back the temp. gauge worked fine for about 2 hours and then it dropped all the way down below 100 again. Neither time has my heat stopped working and the truck seems to be running fine. I just won't be able to tell if the engine overheats until I either smell it or it shuts down. Any suggestions?

ironeagle2006 · Joined: 29 Sep 2006 Posts: 865

Sounds like a Coolant Temp Sensor look for a sensor wired into either the head or near the thermostat housing there will be a wire coming off it. When teh truck is warm will read 5 volts if not sensor bad remove and replace. Simple fix.

bob h · Joined: 15 Oct 2006 Posts: 664 Location: Nb

ironeagle2006 wrote: Sounds like a Coolant Temp Sensor look for a sensor wired into either the head or near the thermostat housing there will be a wire coming off it. When teh truck is warm will read 5 volts if not sensor bad remove and replace. Simple fix.

wrong

ironeagle2006 · Joined: 29 Sep 2006 Posts: 865

I was a CAT FACTORY TRAINED TECH before I was a OTR driver and we were taught always check the sensors on the engine before going into the dash. I was test truck driver for a CAT I was testing the 600 HP 2 years before even hit the production line running team with my father that way it could have the miles racked up fast. I have also rebuilt a Cummins 444 to put 720 HP to the Ground not at the flywheel. For fun in tech school I took a Chrsylor B series block 361 was the start point line bored it out to accept a 426 crank then cut the clearance I needed so the crank throws would clear the block. Word to the wise the 426 was a B series engine the 440 was a C series. I know what I am talking about on engines and diag equipment 90% of all the trucks I drove had CATS in them and I was able to fix and get better fuel mileage than alot of Detroits.

bob h · Joined: 15 Oct 2006 Posts: 664 Location: Nb

randyc wrote: The temperature gauge in my 2000 Pete recently quit working. I had my regulators replaced thinking that they were stuck wide open. Whenever I got my truck back the temp. gauge worked fine for about 2 hours and then it dropped all the way down below 100 again. Neither time has my heat stopped working and the truck seems to be running fine. I just won't be able to tell if the engine overheats until I either smell it or it shuts down. Any suggestions?

to diagnose w/o shooting silver bullets at it, you need to see if scan data agrees with the gauge readout. if scan data were incorrect (ie - bad sensor or harness), it would likely set a fault code or an event code... ANY CODES???... engine light coming on??? checking this first could have saved you from replacing the thermostats for no reason =(

with what little info we have, i would put money on a bad gauge head... as the instrument cluster is likely connected to the ecm through a data link (not sure about this model) as opposed to a designated circuit between the ecm and CT gauge

if the gauge doesn't work "now", this would be an easy diagnosis for a tech with a scanner (i could tell you whether it's engine or cab in abt 2 minutes)

bob h · Joined: 15 Oct 2006 Posts: 664 Location: Nb

quote="ironeagle2006"]Sounds like a Coolant Temp Sensor look for a sensor wired into either the head or near the thermostat housing there will be a wire coming off it. When teh truck is warm will read 5 volts if not sensor bad remove and replace.

vRef should be 5 volts... 'course, it is constant and has nothing to do with the temperature of the engine

return wire should read 0 volts

if the sensor signal wire has 5 volts, the ecm will set a fault code for sensor input signal out of range high. the signal wire should have a voltage between 0.5 and 4.5 volts

Simple fix.[/quote]

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