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ASEMaster35yrs, Chevy Technician
Category: Chevy
Satisfied Customers: 2095
Experience:  ASE Certified since 1972,Master Auto tech,Heavy Truck Tech ,chev dealer tech
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2004 chevy silverado 5.3 i/m monitor resets every time key

Customer Question

2004 chevy silverado 5.3 i/m monitor resets every time key turned to off position. checked power to pins 20 and 57 (power at all times) pins 19 and 75 powered on ignition on, pin 59 powered on start, what would cause pcm to reset monitors when key off?
Submitted: 1 year ago.
Category: Chevy
Expert:  ASEMaster35yrs replied 1 year ago.
Hi, glad to be of help. If your vehicle monitors are resetting when key is turned off, keep alive memory power is being lost. If it reset to the basic key on monitors it means it is losing its memory power. Check all of your fuses. A bad fuse or broken wire may cause the PCM to reset when the key is turned off. The PCM must have a good 12V unswitched power source in order to retain readiness status after the key is turned off. There is a possibility the ECU is losing memory when starting the car with low voltage. There could be a corroded battery terminal as well. If it needs a battery, put one in. The monitor setting process will stop if there are any pending codes. Reprogram PCM with latest calibration.
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Customer: replied 1 year ago.
Can you list KAM circuits? just to make sure I'm not missing anything. Batt, fuses and charging sys are OK.