Engine dies at stop sign

[Thatsgr8]

Need help figuring this one out. Yesterday the wife and I took off to go shopping. Two blocks from house came to a stop sign and the entire truck just shut off. I mean engine dies radio still on. Place in park, try to restart and nothing. Turning the key to run and check engine light is the only light lit on the dash. Turn to start, no response not even a clicking to indicate a weak battery. Turn off and on the ignition, still nothing. Pop the hood, checked the battery cables are good and tight (already replaced battery terminals). Everything is tight. Get back in, turned key back and forth a few times to try to start, nothing and the only light lit on the dash is the check engine. Kept fumbling with the ignition on and off. The stater clicked twice and stopped. This happened three times. Did that a few more times on and off and finally it started up. While it was off I did have dome lights and they did not dim when I tried to start to indicate a dead or weak battery. Even if there was a problem with the battery the alternator keeps the electrical energized so it should not just die when I stopped. I run the ScanGauge II and noticed the electrical was at 14.7 volts when I stopped before it died. Once it started the ScanGauge did show any codes. Where do I start? TIA.

 

[Gpcalero]

Check your engine harness grounds. Might have a loose one.

 

[alrock]

Dead battery - and I mean broken internally, not just worn out. Your symptoms are typical of a failed battery in AZ. The heat breaks them down and they go from working great to nothing in an instant. Grounds are possible too like Gpcalero said, but I'd get that battery tested first.

 

[Thatsgr8]

Ground would make more sense. Az is terrible on batteries for sure.

 

[Thatsgr8]

So after cleaning the terminal with electrical cleaner it did it again. I ordered and replaced yesterday the ignition switch. Went through the 30 minute relearn passcode and it started right away. Drove to the gas station and the mall about 20 minutes away. All went well. Started right up and drove home. Made it all the way home and went to place it in Park and it died again. This time it was different. Turned off, tried to start, nothing. Kept fumbling with the key switch, on off on off, nothing, no dash lights nothing. Dome lights still on so not a battery issue. Then all the dash lights came on but no start. The dash odometer was reading all character symbols, no actual numbers like a reset display or when you first turn the key on display. Key became stuck in ignition and would not shut off to remove it. Finally turned off and key came out, BUT all dash lights and radio still on. After multiple attempts of on off it went to complete off. Waited about a minute and it started right up with no problems. Does this sound like a BCM problem?

 

[jakesz28]

The dome light being on means little to nothing. It will come on with 8 volts on it. The ecm needs 12.5 volts. I would look real hard at the battery and cables. Check all battery connections for corrosion, even at the starter.

 

[Happy Hummer]

Gauge cluster assembly.

 

[Thatsgr8]

Dome lights, stereo, windows up and down, everything except the motor. And it happened two blocks from the house at a stop sign and second time as I pulled into my driveway.

 

[Thatsgr8]

Well I will say I am almost ready to sell this gremlin riddled POS. I have been unable to start the truck because the original issue I posted above worsened. Fumbling with the key on and off does not allow it to start. I went and pulled cleaned and seated all fuses one at a time. Also disconnected both terminals and touched them together. Now not all the dome lights are not coming on passenger side floor comes on dim, but driver side is bright, no overhead (yes the battery has voltage, I checked). When door is open and I rotate key to start and off, system locks and will not allow me to completely remove until I close all doors and turn on off several times then the security light goes off and key comes out. Pulled both plugs on the BCM, cleaned, inspected and reinserted. It is starting to sound like the BCM went bad with all the weird electrical problems. But hey the upside, the radio will still come on and I can listen to that. I could really use some help here guys.

 

[alrock]

I would still try a different battery. I know you're seeing voltage when you test it, but that doesn't mean the battery is intact and working properly. It's at least one of the easiest things to test and many of your symptoms match that of a broken battery. When the truck does not have proper voltage the key gets stuck in the ignition, weird lights go on and off and all kinds of erratic symptoms appear. I've dealt with similar issues. After that it could be a ground issue. For example, the trailer wiring at the back end (assuming you don't have a receiver installed) sits on the metal bumper and can corrode or fray, leading to faults.

 

[jakesz28]

With a dead battery the key will not come out. Do you have a digital volt meter? Do you have a friend that has one. What you describe sounds like a battery with about 11 volts in it and a dead cell. A car battery should never be lower than about 12.4 volts.

If the doors are open lights on. You have electrical draw and the key won't come out. Close the doors, lights go out. Electrical draw drops, voltage is enough for the key release solenoid to release the key.

 

[Thatsgr8]

Tested with digital volt meter 12.4 in rest. I will be removing it to go have a load test performed as well.

 

[powerlifter]

Sounds like a passlock problem. Did you replace that with the ignition switch?