SES When Fans Kick In?
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SES When Fans Kick In?
I have a 92 that throws an SES light when the fans kick-in around 204 deg., then it goes off. I replaced the relays. It runs fine, doesn't overheat or anything, and the light will go off after driving a while. Any other relays I should look for on it?
Thanks.
Thanks.
Melting Slicks
Joined: Feb 2005
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From: Sebastian Florida
St. Jude Donor '06
First off, if the fans are kicking on at 204, then you are throwing a code, that is not heat related.
Have you checked the codes?
Give more info, are you in traffic? Highway?
Is the a/c on?
Does the car run differently after the SYS flashes?
Have you checked the codes?
Give more info, are you in traffic? Highway?
Is the a/c on?
Does the car run differently after the SYS flashes?
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Thanks for the reply.
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It is throwing a code 64, which I believe is a o2 sensor or an ECM issue. The AC is not on at the time, and it does it when it is in city traffic consistently at 204-207 deg, if you continue to drive it will go out. I suspect the ECM has been replaced, it has a sticker that reads 92-93. It's a 92 with 29,000 original miles, starts and runs pretty good, it's hard to gage if performance is down, it is kinda sloggy under 50mph anyways. Thanks for the reply, I really don't trust anyone in the area to troubleshoot this car like a dealer or shop, they will more likely do more damage than good. One more thing, on this year, can you disconnect the batt for a few min. to erase the codes?
Thanks for the reply.
Thanks for the reply.
Still no luck with this , code 64 indicates ECM, O2 sensor or wiring issue, that leaves a lot of rocks to turn over. The thing will consistently throw an SES light even idling, when the 2nd fan turns on, every time without fail. Is there another fan relay someplace on this one other than the ones along side the radiator?
Thanks
Drifting
Joined: Oct 2006
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From: Citrus Heights California
I was just looking at getting a LOW TEMPERATURE FAN SWITCH 200 DEGREES ON / 185 DEGREES OFF from Corvette Central. Their ad says that if you use a low temp switch on a later model C4 you will get a SES light.
Some C4 are programmed to throw a code if the fan comes on before the temp set by the ECM.
Some C4 are programmed to throw a code if the fan comes on before the temp set by the ECM.
Last edited by Kool88vette; Jul 26, 2009 at 10:08 AM.
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Thanks,
It is such a weird deal, let the car idle in the driveway and when the fan kicks on at 200-207 deg. , the SES light comes on immediately, let the car cool off and it goes off. Tha battery in fact could be suspect, I have no idea how old it is, but it seems to hold a charge.
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Racer
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From: Elkton MD
Ses
I was mistaken in saying 'SES' because I confused it with 'SYS'.
Sorry to have perhaps misled you.
That said, if the extra load of the fan causes an error it would be wise to check both ends of the battery cables; especially the frame end of the ground wire.
Kool88vette likely has the real answer.
Please post when you find the actual cause.
Sorry to have perhaps misled you.
That said, if the extra load of the fan causes an error it would be wise to check both ends of the battery cables; especially the frame end of the ground wire.
Kool88vette likely has the real answer.
Please post when you find the actual cause.
Thread Starter
Instructor
Joined: Apr 2003
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I was mistaken in saying 'SES' because I confused it with 'SYS'.
Sorry to have perhaps misled you.
That said, if the extra load of the fan causes an error it would be wise to check both ends of the battery cables; especially the frame end of the ground wire.
Kool88vette likely has the real answer.
Please post when you find the actual cause.
Sorry to have perhaps misled you.
That said, if the extra load of the fan causes an error it would be wise to check both ends of the battery cables; especially the frame end of the ground wire.
Kool88vette likely has the real answer.
Please post when you find the actual cause.
No luck by changing the battery out, but the old one was leaking anyway. The secondary fan comes on at 190 or so every time now, and stays on, same thing, once it comes on the SES light goes on. Car runs fine and really never goes above 220F.
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It seems to have started doing this when the weather got warmer, not sure if that has anything to do with it? With a code 64, I'm leaning toward an ECM issue. If it was an O2 sensor , you would think it would not only come on exactly when the fan does. I sat it out in the driveway a little while ago ,and that secondary fan came on at 154 Deg and stayed on. Thanks for the help
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It seems to have started doing this when the weather got warmer, not sure if that has anything to do with it? With a code 64, I'm leaning toward an ECM issue. If it was an O2 sensor , you would think it would not only come on exactly when the fan does. I sat it out in the driveway a little while ago ,and that secondary fan came on at 154 Deg and stayed on. Thanks for the help
Still working on this issue, another observation is if I kick the fans in by turning the AC on, it does not immediately throw an SES light like it does when it's running with it off. My secondary fan is coming on at 205-207 Deg, I thought on these cars the secondary didn't kick in to around 230 ish.
Thanks.
Drifting
Joined: Oct 2006
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From: Citrus Heights California
Try changing your temp switch to an OEM. They cost $19.95 and you can change it in 2 minutes.
Your aux fan will come on around 226*. That should solve your problem. I think someone put in a low temp switch or the switch is faulty.
Your aux fan will come on around 226*. That should solve your problem. I think someone put in a low temp switch or the switch is faulty.
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Ok, the semp sensor sounded logical, put one in fired the car up in the driveway and the secondary fan came on at 150 deg. and the light went on again. I hate to keep throwing parts at this, but it's beginning to look like an ECM issue. Code 64 indicates ECM or O2 sensors. I'm leaning toward the ecm because it is instantaneous after that second fan kicks in. So far: battery, radiator cap, fan relays and temp sensor.
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I think he was refering to the sensor that I replaced. Where is a reliable place to get an ECM ? seems there are so many people on this board that have gone through several replacements from re-build services.
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Need a little more info, I'm still haveing the fan issues where they kick on at 207dg and throw an SES light, this car still however runs almost perfect. After doing a little more reaearch on the LT1, I found if there is another related issue, where the car is running to cool/rich etc. the ECM will default kick the fans on, to protect further damage. I tried the temp comparison by switching the AC controls to check temp and that looks way out of wack, the temp gage says 207 and the display on the AC lcd says 98? I did a coolant temp sensor, fan relays and new radiator cap. To rule out simple stuff I'm thinking a thermostat or another temp sensor? It still is code 64, which indicates O2 sensors or ECM. Any other ideas?
thanks
Burning Brakes
Joined: Feb 2009
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From: Richmond Virginia
Need a little more info, I'm still haveing the fan issues where they kick on at 207dg and throw an SES light, this car still however runs almost perfect. After doing a little more reaearch on the LT1, I found if there is another related issue, where the car is running to cool/rich etc. the ECM will default kick the fans on, to protect further damage. I tried the temp comparison by switching the AC controls to check temp and that looks way out of wack, the temp gage says 207 and the display on the AC lcd says 98? I did a coolant temp sensor, fan relays and new radiator cap. To rule out simple stuff I'm thinking a thermostat or another temp sensor? It still is code 64, which indicates O2 sensors or ECM. Any other ideas?
thanks
thanks
Code 64 means the ECM is seeing or thinks it's seeing a lean condition (right bank)...could be o2 sensor..could be ecm...also very possible that it is running lean...you need a scan tool capable of monitoring what the
O2 sensor is doing and a FSM for diagnosing the code. Could be a vacuum leak...low fuel pressure....injector(s) bad or partially blocked to name a few...before installing a ecm you need to be sure it's not actually running lean. You say it runs almost perfect. Does it idle smooth or rough/ normal or high idle?
Thread Starter
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Code 64 means the ECM is seeing or thinks it's seeing a lean condition (right bank)...could be o2 sensor..could be ecm...also very possible that it is running lean...you need a scan tool capable of monitoring what the
O2 sensor is doing and a FSM for diagnosing the code. Could be a vacuum leak...low fuel pressure....injector(s) bad or partially blocked to name a few...before installing a ecm you need to be sure it's not actually running lean. You say it runs almost perfect. Does it idle smooth or rough/ normal or high idle?
O2 sensor is doing and a FSM for diagnosing the code. Could be a vacuum leak...low fuel pressure....injector(s) bad or partially blocked to name a few...before installing a ecm you need to be sure it's not actually running lean. You say it runs almost perfect. Does it idle smooth or rough/ normal or high idle?
Thanks