SES, Reduce Engine Power and cooling fan clutch

anthonyl79

Original poster
Member
Jul 15, 2012
127
Colorado
So of course headed out to take the family to the drive in and BAM!!! The SES and Reduce Engine Power light come on. Pull over and and restart the car and the SES stays but the RP light goes off. Drive it to the local parts store and pull the codes. P2135,P2138 and PO641. Come to my favorite site and see what is going on. Looks like some others have had these codes and relate to the stupid cooling fan.

So I went out to check the fan and here is what I did. Started the car, car temp is 210. Reached in and touched the fan. Was able to stop it by applying small resistance to the outside of the fan. I spun it backwards it spun slowly backwards. Then I turned the A/C on while it was spinning in reverse. I would have though the fan should have engaged.

Is this typical operation for the fan??


Thanks in advance!
 

Mooseman

Moderator
Dec 4, 2011
25,494
Ottawa, ON
P2135 CHEVROLET - Throttle/Pedal Position Sensor/Switch 'A'/'B' Voltage Correlation

Possible causes
- Throttle Position Sensor harness is open or shorted
- Throttle Position Sensor circuit poor connection
- Faulty electric throttle control actuator (TP sensor 1 and 2)
- Faulty accelerator pedal position sensor

P2138 - Accelerator Pedal Position Sensor Circuit Range/Performance

Possible causes
- Accelerator Pedal Position Sensor harness is open or shorted
- Accelerator Pedal Position Sensor circuit poor electrical connection
- Faulty Accelerator Pedal Position Sensor
- Faulty Electric Throttle Control Actuator

P0641 CHEVROLET - 5 Volt Reference Voltage Incorrect

Possible causes
- ECM Short circuit condition
- Shorted sensor on 5 volt circuit
- Failed ECM

Something is screwing up the 5V reference voltage that all sensors use. First check all the fuses, especially all of those for the PCM and ignition. If they check out, then I would replace the pedal position sensor as this one is throwing two codes. It might have shorted out and screwing up the 5V reference. If that doesn't fix it, then this is likely a more serious problem with the PCM as the 5V is not within specs. At this point, further diagnosis would require a dealer to fully diagnose using a Tech2 scanner.
 

anthonyl79

Original poster
Member
Jul 15, 2012
127
Colorado
Do you think it would be worth while to swap the TB? I have a spare sitting here, or just a waste of time? I had read on somewhere that people where having the issue and the TB was the problem. Also others have said that the clutch for the fan could be the issue. I have a spare one of those as well.
 

Mooseman

Moderator
Dec 4, 2011
25,494
Ottawa, ON
It's not the TB. It's the pedal position sensor on the pedal. Haven't heard of a TB failing but I guess anything is possible.
 

anthonyl79

Original poster
Member
Jul 15, 2012
127
Colorado
Mooseman said:
It's not the TB. It's the pedal position sensor on the pedal. Haven't heard of a TB failing but I guess anything is possible.

Well replaced the TB and same thing. At least I was able to clean it, it was due. Well I guess time for the TP sensor.
 

CaptainXL

Member
Dec 4, 2011
2,445
Isn't this that infamous fan clutch harness short issue? It happens when the 5 volt reference wire that these sensors share gets frayed. The solution is to replace the harness leading up to the fan clutch
 

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