need help with a cooling fan problem
02-02-2009, 09:47 PM
#1
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need help with a cooling fan problem Ok just to start this off this is not for a ls1 but i went on other forums and got no anwsers. This is for a 2.2 cavalier 94. The problem is the cooling fan for the engine will not come i jumped the fan it worked. relay is good and so is the wiring for the relay. but when the engine gets hot it wont come on when i turn on the ac it wont and it wont if i pull the ect sensor wire. I even jumped the 2 wires for the ect to make it think it was at 280 degrees and no cooling fan what could be the problem?
And thanks for any help.
And thanks for any help.
02-02-2009, 10:02 PM
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but if i unpluged the harness from the sensor shouldnt the fan have gone on? i think it should have gone on when i jumped the wiring for the sensor so i thought it was at 280 degrees.
02-02-2009, 10:59 PM
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No the engine wasnt really 280 it only read that becuase i jumped the power and ground on the sensor wire so the computer would have thought it was over heating to try and force the fan to come on. and Wouldnt unpluging the ect sensor wire put it in fail safe mode and the fan should come on then
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02-02-2009, 11:25 PM
#8
No the engine wasnt really 280 it only read that becuase i jumped the power and ground on the sensor wire so the computer would have thought it was over heating to try and force the fan to come on. and Wouldnt unpluging the ect sensor wire put it in fail safe mode and the fan should come on then
I really don't know about that model car. sorry.
03-04-2009, 11:17 PM
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hey. i have had the same problem in my 99 ss. i have replaced the sensor and checked all the fuses and relays. still nothing. also my temp gauges reads around 180 to 210 all the time but i know the engine isnt nearly that hot. anyone know?
03-06-2009, 01:23 PM
#12
it's probably in the PCM or wiring to the pcm,
for the things like that which the pcm controls, take the cooling fans for instance,
all the pcm does is close a circuit to ground to activate the fan relay, then the fan relay switches high current to run the fans. So if you've checked everything else, but the computer doesn't turn the fans on, then it's either that transistorized circuit in the pcm or the wiring to the pcm. what you can do is find which wire going to the pcm it is, and somehow simulate an overheat condition to make the pcm want to turn the fans on, and see if that circuit into the pcm goes to ground. If it doesn't, then it's in the pcm. be careful to check the wire running from the pcm to the fan relay though, don't conclude it's a bad pcm when it's a bad wire or connector somewhere outside the pcm.
if you unplug the temp sender from it's wiring, it'll make the pcm think the engine is stone cold. The temp sender works on resistance, hot is low resistance down to continuity, so if you ground the temp sender wire the gauge should flop over to the right at the high temp. Cold is high resistance, and an open circuit will keep the needle fully left on the cold side of the gauge. To fool the pcm for hot condition, you ground the temp sender wire, if it's a two wire sender then you just get a paper clip or similar and shove it into the connector that plugs into the coolant temp sender.
the temp gauge on the 99ss should read at or just a hair below the 210 mark which is the needle straight up on the gauge. The temp sender is less sensitive in the operating range to help the gauge needle not move so the driver does not think there's a problem, it a gay rationale but that's what they do. Get over 230-240F and the needle should move quickly to the right. The temp gauge is not linear.
for the things like that which the pcm controls, take the cooling fans for instance,
all the pcm does is close a circuit to ground to activate the fan relay, then the fan relay switches high current to run the fans. So if you've checked everything else, but the computer doesn't turn the fans on, then it's either that transistorized circuit in the pcm or the wiring to the pcm. what you can do is find which wire going to the pcm it is, and somehow simulate an overheat condition to make the pcm want to turn the fans on, and see if that circuit into the pcm goes to ground. If it doesn't, then it's in the pcm. be careful to check the wire running from the pcm to the fan relay though, don't conclude it's a bad pcm when it's a bad wire or connector somewhere outside the pcm.
if you unplug the temp sender from it's wiring, it'll make the pcm think the engine is stone cold. The temp sender works on resistance, hot is low resistance down to continuity, so if you ground the temp sender wire the gauge should flop over to the right at the high temp. Cold is high resistance, and an open circuit will keep the needle fully left on the cold side of the gauge. To fool the pcm for hot condition, you ground the temp sender wire, if it's a two wire sender then you just get a paper clip or similar and shove it into the connector that plugs into the coolant temp sender.
the temp gauge on the 99ss should read at or just a hair below the 210 mark which is the needle straight up on the gauge. The temp sender is less sensitive in the operating range to help the gauge needle not move so the driver does not think there's a problem, it a gay rationale but that's what they do. Get over 230-240F and the needle should move quickly to the right. The temp gauge is not linear.