How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Jerry Newton Your Own Question
Jerry Newton
Jerry Newton, Chevy Technician
Category: Chevy
Satisfied Customers: 4412
Experience:  ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
25345654
Type Your Chevy Question Here...
Jerry Newton is online now
A new question is answered every 9 seconds

I have a 1999 GM2500 that all of a sudden turns over but

Customer Question

Hello I have a 1999 GM2500 that all of a sudden turns over but won't start. It's throwing codes P1626 and U1192. The security light is on steady.
Submitted: 1 year ago.
Category: Chevy
Expert:  Jerry Newton replied 1 year ago.

P1626 tells us that the engine computer is not receiving the theft deterrent password ***** allow the engine to start.

This can be due to a faulty lock cylinder, body control module, or powertrain control module. However, the first thing you should do is attempt to relearn the theft deterrent password, which you can do without any tools, and this technique is often successful.

The process takes 30 minutes, and goes as follows. Attach a battery charger to the vehicle to make sure the battery doesn't go dead during this process:

Attempt to start engine, leave key in ON position. Note security light is ON or FLASHING at this time. Wait ten minutes, until security light goes off.

Turn key off for a few seconds, then attempt to start, leaving key ON. Note security light again, and leave key on for ten minutes until light goes out.

Turn key off for a few seconds, then attempt to start, leaving key ON. Note security light again, and leave key on for ten minutes until light goes out.

So, this is three ten minute cycles, equaling 30 minutes. After the last cycle, turn key off, then see if truck starts. If not, then there is something else wrong. Check fuses, but know that if there is something else wrong, professional diagnosis is strongly recommended, as it's expensive to "guess" at the problem here. A new PCM or BCM requires programming, and if you need a lock cylinder, you'll also need to have the password ***** again. If relearning it doesn't work, you'll need to have a mechanic look at this with his scan tool to determine the issue.