PULSING VOLTAGE SHORT! HELP!!

[Carman52]

Here's my problem. 2003 Tahoe RWD 5.3l

After a two month period while waiting in my shop for a transmission the truck failed to crank.

1. I discovered a positive short to ground, resulting in a no crank condition and loss of almost everything, no radio,interior lights, door locks or anything. There is roughly 6.4 volts to ground.

2. The key feature is a 1 Second interval, voltage pulsing to ground. The pulsing doesn't stop even with the key out of the ignition, cylinder and ignition are both out. The fuel pump also runs in 1 Second intervals with the key out of the car.

 

3. Voltage pulsing continues when I pull the fuel relay, only the pump stops with the relay pulled but my voltage light continues to pulse. The voltage light is connected to battery ground and the probe to the firewall groundstrap.

Ignition, PCM, BCM are disconnected and starter removed. Oil pressure and coolant sensors are disconnected. Rear harness to lights and fuel flow module are disconnected.

4. No blown fuses.

5. NO power to IGN1 40a fuse.

 

Inspection of the underhood fuse panel, underdash wiring and components all seem sound. Only when I pull the large, rectangular connector blocks do I get it to stop giving a general idea of direction.

 

This is pretty strange. I thought maybe rodent damage but I can't find it, although I haven't dropped the fuel tank to inspect wiring yet.

 

I need help on this and would appreciate it! What the hell can cause this?

[sefiroxx]

Need to pull fuses and relays one at a time while monitoring meter.

 

Sent from my XT1053 using Tapatalk

[Carman52]

Yes, forgot to mention I pulled all fuses and relays as well.

[silveradosid]

did you disconnect alternator

[Carman52]

Yes, disconnected the alternator too.

[rjgti]

have a look at battery cables and all ground points

[vinemann12]

I noticed you live in North Washington area with the historic / standard heavy rainy seasons, lots of moisture,, etc..

 

Poor electrical connections in general will cause many weird conditions with truck and boat systems..

I would first start by cleaning all engine and system grounds and apply good water sealer to connections after..

Find your electrical diagram, as it will point out the the physical connectors and grounds to first check out.

Also,, recommend using VOM / Volt-Ohm meter to vaidate connections and of course voltages.

 

If you see any connectors with the green crud inside,, cut-off old and solder in new connector's with shrink tubing to seal joint..

 

I do realize my comments are shot-gun type but they are a good place to start to issolate your problem or multiple issues..

 

Cheers----K

[silveradosid]

do you have power seats, maybe seat memory module