Electrical problems are the worst

bmwill60 · May 1, 2019

So a little bit of background, I wrecked my 2000 GMC Sierra 2500 and am restoring it. I got a cab from a 99 2500 and I am currently ready to start it but there is a problem. It starts but then dies immediately. I rented an Autozone scan tool and read a code P1631 (Theft Deterrent Start Enable Signal Not Correct). This code makes sense because I used the donor trucks steering column and installed the lock cylinder from the truck I wrecked. I thought it was a simple key relearn after some research. Well, it hasn’t worked. When my key is on for the 30 min procedure, all that comes on is the battery light. All of the connections seem good. Any ideas?

bmwill60 · May 2, 2019

Ignition switch is ruled out because I replaced it with the one from my wrecked truck and no difference.

The ignition fuses are all in tact. They had corrosion on them so I cleaned them up but again. No difference

sefiroxx · May 2, 2019

Check fuel pressure during on and then crank.

bmwill60 · May 3, 2019

I feel really dumb but, I’m having a tough time reading pressure. I have an OEM tools gauge but it reads no pressure on my truck and on my perfectly running car. It’s like reading air pressure in a tire right? The test port has a Shrader valve and the fitting that screws on should have something to depress that valve to read the pressure. My tool has nothing to press the valve down. Broken tool? The fuel pump can be heard very clearly and when I press down the valve with a screwdriver, fuel sprays out. The fuel pump has been just replaced just to let you know.

sefiroxx · May 3, 2019

You may be using a permanent mount type visage.

Yes, a mechanics test guage has a prong to depress the shader valve. There are adapters for HVAC dishes that do that so you might try a supplier for one

bmwill60 · May 4, 2019

With key on, engine off, the rating is 55-62 psi. I get about 55 when the pump is running and I kicks down to about 52 before I try and start. When it cranks, it fluctuates but rises back to 55 when it fires for about 2 sec. I don’t think fuel pressure is the issue. I might just have to get my hands on a Tech II scanner

sefiroxx · May 4, 2019

Fuel system working.

Let's go back to 1631, try the security relearn process:

Security Relearn Procedure:

-Insert key, attempt to start the vehicle and leave the key in the ON position.
In some vehicles, the Battery and Security light will blink for several seconds, and then shut off. Then the Security light will then remain ON. Leave the ignition ON until the Security light goes OFF. This will take more than 5 mins.
-When the Security light goes OFF, turn the ignition to the OFF position.
-Leave ignition OFF for 20 Seconds.
-Attempt to start the vehicle again and leave the key in the ON position.
-In some vehicles, the Battery and Security light will blink for several seconds, and then shut off. Then the Security light will then remain ON. Leave the ignition ON until the Security light goes OFF. This will take more than 5 mins.
-Turn the ignition to the OFF position for 20 Seconds.
-Attempt to start the vehicle again and leave the key in the ON position.
-In some vehicles, the Battery and Security light will blink for several seconds, and then shut off. Then the Security light will then remain ON. Leave the ignition ON until the Security light goes OFF. This will take more than 5 mins.
-Once this entire procedure has been completed (three times) your vehicle will start on the fourth attempt.

Note: Some vehicles perform the relearn in a different sequence. You may notice your security light, battery light and abs light will alternate. Once the security light is left out of the sequence that is considered one step. Repeat the procedure two more times and on the fourth time your vehicle will start.