Temp Light on Dash

Frank_C

Not-quite-so-new-guy
Dec 28, 2020
12
3
Hi all - I have a 1984 Oldsmobile Cutlass Supreme 3.8L V6 and after starting the car and letting it run for a couple of minutes, the TEMP dummy light on the dash starts flickering. It does not stay solid red but flickers very faintly. Any ideas what could be wrong here? Bad temperature sensor? Bad water pump?
 

JimmyCamino

Not-quite-so-new-guy
Dec 15, 2020
46
8
Alexandria, VA
Agree, probably the temp sender. Remember, always consider bad or insufficient ground on any electrical problem And if you don't have one already, take this as an opportunity to invest in a new tool / diagnostic equipment, like a contact thermometer. Many multi-meters have that feature. Infrared are fun but reportedly not as accurate as contact. Good luck with and enjoy fixing the problem.
 

Frank_C

Not-quite-so-new-guy
Thread starter
Dec 28, 2020
12
3
Thanks, just starting throwing code 15, so planning to replace the coolant temperature sensor.
 

Frank_C

Not-quite-so-new-guy
Thread starter
Dec 28, 2020
12
3
Ok, located what I think is the coolant temperature sensor, which disintegrated after one tug. Here are the photos of the wire connection and sensor. Should I replace connector and sensor? Any suggestions would be greatly appreciated!
 

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Frank_C

Not-quite-so-new-guy
Thread starter
Dec 28, 2020
12
3
Ok, looks like I am going to be replacing 2 switches. What does the ECM temp switch do? This switch sits right below the radiator inlet housing.
 
Last edited:

pagrunt

Geezer
Sep 14, 2014
6,289
113
Elderton, Pa
It just informs the ECM of the engine temp to help regulate the carb. It has nothing to do with the warning light & only ties into the ECM.
 
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Frank_C

Not-quite-so-new-guy
Thread starter
Dec 28, 2020
12
3
It just informs the ECM of the engine temp to help regulate the carb. It has nothing to do with the warning light & only ties into the ECM.
Ok, I located the coolant temperature sensor right behind the alternator on the front passenger side of the engine and there was no wire connected to it. After some initial searching, I cannot locate the connector anywhere nearby, but it is tight space, so I might have to remove the alternator to do more searching.
 
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