Truck wont start after mail order tune throwing P1631
12-29-2007, 03:38 PM
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Truck wont start after mail order tune throwing P1631
I recently ordered a replacement PCM from Nelson Performance to tune out P0420 and P0430 emissions codes after installing a set of long tube headers on my 2003 Silverado SS. I installed the new PCM today and the truck will not start, it cranks but no ignition and throws code "P1631 Theft Deterrent Password Incorrect". When I swap my stock PCM back in it starts right up.
Anyone have any ideas if this is something I can fix or was the PCM programmed incorrectly?
Anyone have any ideas if this is something I can fix or was the PCM programmed incorrectly?
12-29-2007, 03:57 PM
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You need to reset the security code in VATS.
1. Turn the key on to start the engine, then release the key to the ON position.
2. The security light will flash for 10 minutes then go off.
3. Turn key OFF after security light has stopped flashing.
4. Leave the key off for 30 seconds or so. Not sure if you have to wait but it won't hurt. Repeat steps 1 to 3 for 2 more times for a total of 3 attempts. The vehicle should start on the 4th attempt. This procedure takes at least 30 minutes. The battery should be fully charged and deliver more than 10 volts.
These instructions should have been included with your PCM from Nelson!
1. Turn the key on to start the engine, then release the key to the ON position.
2. The security light will flash for 10 minutes then go off.
3. Turn key OFF after security light has stopped flashing.
4. Leave the key off for 30 seconds or so. Not sure if you have to wait but it won't hurt. Repeat steps 1 to 3 for 2 more times for a total of 3 attempts. The vehicle should start on the 4th attempt. This procedure takes at least 30 minutes. The battery should be fully charged and deliver more than 10 volts.
These instructions should have been included with your PCM from Nelson!
12-29-2007, 04:18 PM
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You need to reset the security code in VATS.
1. Turn the key on to start the engine, then release the key to the ON position.
2. The security light will flash for 10 minutes then go off.
3. Turn key OFF after security light has stopped flashing.
4. Leave the key off for 30 seconds or so. Not sure if you have to wait but it won't hurt. Repeat steps 1 to 3 for 2 more times for a total of 3 attempts. The vehicle should start on the 4th attempt. This procedure takes at least 30 minutes. The battery should be fully charged and deliver more than 10 volts.
These instructions should have been included with your PCM from Nelson!
1. Turn the key on to start the engine, then release the key to the ON position.
2. The security light will flash for 10 minutes then go off.
3. Turn key OFF after security light has stopped flashing.
4. Leave the key off for 30 seconds or so. Not sure if you have to wait but it won't hurt. Repeat steps 1 to 3 for 2 more times for a total of 3 attempts. The vehicle should start on the 4th attempt. This procedure takes at least 30 minutes. The battery should be fully charged and deliver more than 10 volts.
These instructions should have been included with your PCM from Nelson!
Thanks
Phil
12-30-2007, 05:46 PM
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Well the 3 cycles worked once I disconnected the negative terminal on the battery and reconnected it. Now its time to put some miles on it before going to emissions tomorrow. It just started snowing here again.
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12-31-2007, 11:16 AM
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Good to hear you got it working. Not sure why you had to disconnect the battery but maybe to clear any codes previously set. 
It is snowing now and it is supposed to snow here for the next 3 days.
It is snowing now and it is supposed to snow here for the next 3 days.