LS1 PCM Cooling Fan triggers
01-29-2012, 03:27 PM
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LS1 PCM Cooling Fan triggers My LS1 PCM has been modified by a company to remove certain features.
The cooling fan triggers for Fan 1 and Fan 2 are permenantly locked to ground when the engine is running. (No AC and engine is cold) If I have fan relays connected to these triggers the cooling fans run continuously.
What PCM program changes could cause this situation?
The cooling fan triggers for Fan 1 and Fan 2 are permenantly locked to ground when the engine is running. (No AC and engine is cold) If I have fan relays connected to these triggers the cooling fans run continuously.
What PCM program changes could cause this situation?
02-01-2012, 09:25 AM
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More data Engine cold, start engine, both fans run (each wired separately thru their own relay to fan triggers). After about 35 seconds the fans stop, engine falters (or lowers rpm) and then fans re-start and engine picks up.
This repeats itself avery 35 seconds and happens really fast. No codes.
My Tuner says that AC system has been removed from the PCM
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This repeats itself avery 35 seconds and happens really fast. No codes.
My Tuner says that AC system has been removed from the PCM
Searching for Ideas
02-01-2012, 12:21 PM
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Problem solved After much head scratching I narrowed the problem down to the fact that the fans were being forced on. Only Temp sensor, VSS and AC Pressure switch could do this.
As I don't have an AC pressure switch sensor, temp sensor is new and vehicle is stationery it must be the AC Pressure sensor who's signal goes to Red Pin 14. So in desperation I cut this wire and Bingo....fans start up at correct temperature.
Not sure why my modified harness is doing this but there seems to be a varying DC voltage between 0.9 and 3 volts on this line with the engine running.
Eureka!
As I don't have an AC pressure switch sensor, temp sensor is new and vehicle is stationery it must be the AC Pressure sensor who's signal goes to Red Pin 14. So in desperation I cut this wire and Bingo....fans start up at correct temperature.
Not sure why my modified harness is doing this but there seems to be a varying DC voltage between 0.9 and 3 volts on this line with the engine running.
Eureka!
