Is your a/c on? If sitting idle, the fan will come on to cool the a/c condenser about every 30. -60 seconds. If so, that tells me everything is good with your solenoid. I would be looking at your coolant temp sensor as being the problem if it’s not cooling the radiator when needed
Auto fan randomly working in 379 with Detroit 60
Discussion in 'Peterbilt Forum' started by simonsocm, May 18, 2021.
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Well I replaced the radiator and the coolant temp sensor for the ecm. Still not turning on when it should. When I get home next week I'm going to check the wiring to the coolant temp sensor from the ecm.
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Nope, no code for coolant temp sensor. I'd assume it would've said something along the lines of voltage high if the resistance was super high. I'm still going to check the wiring when I get home next though. Only code I had was for a high voltage for coolant level sender that I just temporarily fixed with a butt connector and lots of electrical tape for stability and sealing.
Not a thing for the coolant temp sensor.Don379 Thanks this. -
I had a thought on this. Could something like an intermittent bad ground for the sensors cause something similar to this? Or would that throw codes?
Also where would the instrument panel ground be located? Maybe it truly is the coolant temp gauge and coolant warning switch has an intermittent dirty ground. -
All those sensors go to ecm. IF bad ground and sensor wasnt working, you would throw a code. All you have to do to check and see if this is accurate is next time you have truck running, unplug the sensor and see if check engine light comes on. It should. Why do you want to check grounds to instrument panel? Everything works on instrument panel correct? I think what you need is for a diesel shop to plug into ecm with laptop. This would tell you immediately where the fault is if any at all. If funds allow, you should buy the communicator and software for your laptop.
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All the other gauges seem to work as intended still. -
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Been awhile, did some poking around this weekend. Fixed an ecm power issue and cleaned the ecm connections with electrical contact cleaner. I also checked ohms from the ecm to the coolant sensor and got 0 ohms. Same with the ecm grounds.
I think I'm gonna check if the sensor is actually getting 5v or not. If its getting 5v then I'm gonna assume the ecm is going bad. If its not getting 5v then I'm guessing maybe a bad spot in the harness?
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