Quck PCM swap question
01-04-2016, 10:18 PM
#1
Quck PCM swap question I have a maddening intermittent problem with the MAF circuit in my truck. It's a 2003 5.3. I believe the PCM itself may be the cause.
I have a replacement stock PCM with the correct VIN and stock programming in it, I'd like to swap it in.
When I do, the security lock out kicks in.
How do I get around this WITHOUT a GM Tech tool?
I have a replacement stock PCM with the correct VIN and stock programming in it, I'd like to swap it in.
When I do, the security lock out kicks in.
How do I get around this WITHOUT a GM Tech tool?
01-05-2016, 09:32 AM
#3
AHH, security relearn. I've heard of this before. I was told the Tech Tool was required. I searched and found this on another forum specific to GMT360 trucks, I'll assume it's correct:
================================================== ==============
I got this GM security relearn procedure from a friend who is a ASE certified technician.
After you install the new pcm (make sure your pcm is indeed flashed specific to your vin) try to crank the truck by holding the key to the start position without letting go. It won't start and the security light will continue blinking while you hold the key to the start position. Release the key to the on/running position (do not turn off).
Wait 11 minutes (cannot be any less than 11 minutes) with the key left to the on/running position. The security light will remain on for the time being and will eventually turn off by itself.
While you wait, it would be wise to turn off all accessories and interior lights, dim the dashboard lights, and bypass the daytime running lamps (DRL) to avoid draining the battery since this is a ridiculously long process. To bypass the DRL, turn the headlamp switch counter clockwise to the farthest left setting and hold the switch to that position for 3 seconds and release. The DRL will be switched off, however it will come back on by default during each cycle, so yes it is a pain to do it again and again, but it ensures that your truck will have enough juice to start.
After the 11 minutes is up, switch the key to off position for 30 seconds (cannot be any less than 30 seconds).
Switch the key back to on/running position (do not attempt to start the truck just yet) and wait another 11 minutes.
Switch the key back to off position for 30 seconds.
Repeat this cycle four more times.
But on the final 6th cycle, after switching the key to off position for 30 seconds, switch the key to the on/running position for a split second so the security light can come on, then immediately crank the truck before all the chimes and instrument cluster icons go off. THIS IS THE ONLY POSSIBLE WAY I GOT THE TRUCK TO START.
================================================== ==============
I got this GM security relearn procedure from a friend who is a ASE certified technician.
After you install the new pcm (make sure your pcm is indeed flashed specific to your vin) try to crank the truck by holding the key to the start position without letting go. It won't start and the security light will continue blinking while you hold the key to the start position. Release the key to the on/running position (do not turn off).
Wait 11 minutes (cannot be any less than 11 minutes) with the key left to the on/running position. The security light will remain on for the time being and will eventually turn off by itself.
While you wait, it would be wise to turn off all accessories and interior lights, dim the dashboard lights, and bypass the daytime running lamps (DRL) to avoid draining the battery since this is a ridiculously long process. To bypass the DRL, turn the headlamp switch counter clockwise to the farthest left setting and hold the switch to that position for 3 seconds and release. The DRL will be switched off, however it will come back on by default during each cycle, so yes it is a pain to do it again and again, but it ensures that your truck will have enough juice to start.
After the 11 minutes is up, switch the key to off position for 30 seconds (cannot be any less than 30 seconds).
Switch the key back to on/running position (do not attempt to start the truck just yet) and wait another 11 minutes.
Switch the key back to off position for 30 seconds.
Repeat this cycle four more times.
But on the final 6th cycle, after switching the key to off position for 30 seconds, switch the key to the on/running position for a split second so the security light can come on, then immediately crank the truck before all the chimes and instrument cluster icons go off. THIS IS THE ONLY POSSIBLE WAY I GOT THE TRUCK TO START.
Last edited by Paul Bell; 01-05-2016 at 09:39 AM.