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My cooling fans are turning off mid-drive. Here is what I know:
* Swapped hi and lo speed relays with working ones, no change.
* Fans work immediately after starting vehicle for 5-10 seconds every time, then turn off. I feel this rules out an electrical issue at the fans themselves.
* The issue ‘fixed’ itself some how. I drove yesterday and half of today with no problems. Fans shut off mid-drive again today.
* Coolant temperature sensor works normally, I just replaced it a few months ago as well.
* I don’t think the a/c pressure transducer faulting would cause both fans to stop working.
* a/c compressor clutch engages when starting vehicle, blows cold air for a few seconds until fans turn off.
* Heat works and there does not appear to be any air in the system. Coolant level stays constant between drives.
* No CELThe cooling fans were replaced 3 months ago as well as the coolant temperature sensor. I had to replace the fans due to a failed RFI module which shorted out, melting the resin inside. However, my a/c fan was still functional and only the main cooling fan itself was not working. Since the fans work for a few seconds after starting the vehicle, I have a hard time believing there’s an issue there. Something is not telling the fans to operate.
Looking at the wiring diagram, the only conclusion I can come to is a short to the PCM or a faulty PCM itself.
Anyone have any ideas?
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The car has cooled off and now the fans seem to be working again. It’s a very weird issue. I’m wondering if the relays could be failing or overheating. But I’ve swapped them around once and the issue arose again which leads me to believe it is not related to the relays.
I also don’t think the PCM would be affected by engine temperature. It also doesn’t make sense since with the a/c on, the fans should come on as well regardless of engine temp. And why would they work on start up only to not work seconds later even with a/c on or engine over 220F…?
It seems there is at least one thing ruling out each component.
Suggest you hook a DVOM to the fan and see if your loosing the supply voltage to the fan or not.
If you still read power at the connector when the fan stops, then you have a faulty fan.
If you loose the supply power to the fan you’ll need to back trace the power from the fan and see where it is being lost.I’m wondering if my alternator is failing causing these issues. I recently began hearing this sound from under the hood:
https://vocaroo.com/i/s1EMuXftttf6When I put my ear up to the alternator it sounds loudest, but when I step back it sounds more like in the middle of the engine.
Today, when it happened again, I restarted the car and left the a/c off and the fans stayed on. It only seems to happen when car is up to operating temp.
Today showed my transmission also behaves strangely while this is going on.
Everything is fine until the car warms up and the fans cut off. Then the shifting is odd. Sometimes it’ll shift from 1st to 2nd then back to 1st then to 2nd, 3rd, etc. Sometimes it’ll jolt forward (slightly) at a stop while in gear. Like the transmission tries to engage for a second.
Figure I’ve either got a PCM issue or there is a ground issue in that circuit. Thinking more towards PCM as it happens pretty predictably once the engine warms up.
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