4x4 hell.

[dweber]

Ok in short, I have a 99 chevy suburban 2500 with the 7.4. 4wd light came on after a heavy rain storm and now it doesn't work. Here is what I've done and checked I'm scratching my head at this point. Any help is greatly appreciated.. I've replaced the square selector switch on dash, old one was always half lit. Still no go scoured the bottom of truck for problems and discovered what I thought was the problem somehow the encoder motor wires shifted too close to the drive shaft and rubbed three out of 4 Clean through, so I spliced and repaired those and still nothing. Now what? Here's what happens everytime, you key the truck in the on position selector switch lights everything up once and shuts off, while this is happening you can hear the tccm click 5 times and that's it. Selector switch goes dead no lights indicating what drive it's in. Stuck in 2h btw.. I don't want to just keep throwing parts at it either. Oh and fluids are all recently checked and changed and checked again since this has happened. Never has any issues other than the selector switch sometimes didn't light up correctly, other than that it has always been flawless. I've looked for the infamous ground wire I've read about but apperently it's different on the 7.4 because where it's supposed to be bolted to the frame there's not even a hole for a bolt.

I did go down to orillies and was given these codes.

C0309 shift motor circuit high

C0310 shift motor a/b curciut open

C0323 transfer case lock circuit low

U1026 loss of transfer case shift control module class 2 communication

 

These were read before I discovered the wires but there's still something going on.

 

I plead to the gear head gods help me!

[StepsideGMC]

It sounds like a corroded ground, or several.

[barry G]

once parts are swapped, clean real good on top of tranny, down behind bellhousing. Nature can steal the path, even after good.

 

I triggered an abs light with a Hurst shifter. About as bizarre as a problem can get.

Crazy elements... cleaned it off, it is like new.

Another weird thing..

 

swap the actual lights that you are looking at for new versions of the same light. I could not use LED on any lamp that involved a computer, went back to old version. all normal..

 

these ideas are only after verifying all the stuff is good. The real ground etc.

[00Silverado4x4]

You said it quit working after a rain storm? I'd double/triple check every connector that you can find to make sure it clean, dry and tight. You may have some water or corrosion somewhere in the electrical that's causing you issues.

[diyer2]

No problems shifting transfer case until wires were damaged?

Lets start with the wires that were damaged because I think this is where it started. The wires were put in harms way when the fluids were changed? Possible.

When you repaired the wires did you solder and shrink tube the wires? This is the only way to do the wire repair IMO.

I would start with the damaged wires making sure they are quality connections, then I would put the original parts back in. If this doesn't fix it then the shifting solenoid on the trans may have been dmamged when the wires were shorted, damaged.

I always try to start with basics and eliminate simple things.