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1991 GMC 2500 V8 4WD - Front axle quit working. - HELP ! ! !

RayMich

RayMich

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1991 GMC 2500 V8 4WD - Front axle quit working. Only rear wheels are driving now regardless of being shifted in 4-Hi or 4-Lo. Every thing worked fine until a few minutes ago when engine was shut down. Now after re-start, only rear wheels are driving. This is my son's plow truck and he need it for work tonight.

Have tried shutting down engine and re-start it. Also have tried 2WD and 4-Hi and 4-Lo. Tried driving forward and backward and the front axle still won't lock-in.

Truck did get a CEL, but the codes are 13, 32 and 44, which appear to be emission related.

How does this truck lock-in the front axle? Is it possible that some solenoid froze up from ice build-up? Is there something that can be done manually to get the front axle to work?

Any help is greatly appreciated. Thanks
 
ak diesel driver said:
thermo linear actuator has gone bad it's found in the front axle
Click to expand...

AK DD, thanks for your assistance.

How difficult is it to replace this actuator? Is it very expensive?

Is it possible that I may have a broken electrical connection somewhere? It is weird that it worked one minute, but after re-starting the engine, now it doesn't work. Is there some way to check the electrical circuits?

Thanks.
 
easy to replace somewhat expensive tho. check for power to it they do get slower to engage with age but are known problem. Might check into using the newer electric style. I'll see if I can find a good thread on it.
 
Last edited:
Well, the problem definitely IS the TLA.

Pulled it out, and made sure the electrical connection is good and it seems to be working right now. It is warming up when electrical power is applied and at least on the hoist the 4WD is working. Hopefully it will keep working tonight so we can go out and make some money plowing.

Tomorrow we will look into getting either the electric motor version, or call the company that makes the Posi-Lok and see if we can convert this damned thing to be mechanically actuated. The company is located in Coldwater, Mi which is 70 miles from my house. I'll drive down there if I have to.

Thank you AK DD for your assistance.

I'll keep you posted on what we end up doing.
 
Yes, it is strictly a plow/work truck. We just spent $2,100 to have the transmission rebuilt after it blew reverse while plowing and another $500 in repairs to the plow. Also had to replace the radiator that for some reason blew out the drain cock while on the expressway, blowing coolant all over the place. Damned plastic end caps on the radiator so we couldn't fix it and had to buy a new one. That was another $220 for parts and labor. Fortunately my son shut it down right away and didn't damage the engine. Truck still needs some work, but it has to earn its keep now.

Hopefully we will be able to take care of the plow contracts tonight without any more problems and we can worry about upgrading that damned TLA tomorrow.

We learned a lot under fire tonight!

Thanks again for the help bro!
 
If you need absolutely positive and reliable lock on your front drive, and it sure sounds like you do, I would strongly suggest the Posi-Lok. I recently did that mod and highly reccommend it.

When you pull that cable it is locked, no question. It is not hard to install either. Took me maybe three hours total over a couple days. I actually didn't keep track of my time so this is just a guess.

My biggest concern was going through the firewall, but that turned out to be easy. I have a 94 K2500 so the APP body got in the way of where the Posi-Lok directions said to drill the hole for the cable. Just a bit to the left of the APP body was a plastic plug in the firewall. Checked the engine side of the firewall and that plug was in a good area so I pulled it. It turned out to be a square hole, but the perfect size to fit the grommet and cable and still seal off the square corners of the hole.

The directions call for you to drain the diff oil, I didn't. I ran both pass side wheels up on ramps to get the TLA to what I guessed to be above the gear oil level. It worked, no mess, no oil loss.

I clipped the TLA wires between the TLA and the connector and put the connector end back onto the wire loom. I did this so if I needed to a new TLA could be retro-fitted. The wires I tucked up out of harms way. I don't know now why I would ever go back to the TLA.

Don
 
This damned plow truck is JINXED! :banghead:

Some how the power to the TLA is very erratic and weak. On the test bench, the TLA worked fine with a strong force, but plugging it to the harness on the truck it is very weak and mushy, so he ended up hot-wiring the TLA directly to the battery and that works for now. Just have to remember to unplug it when parking the truck.

I was planning to drive down to Coldwater to buy the Posi-Lok kit, but the damned truck DIED while working last night. Looks like the ignition switch inside the steering column is F'ed up now. He was able to take care of only HALF of the contracts. Fortunately another guy finished them off for him.

I had to go out at 6:30 this morning and tow the plow truck back to the shop.

The '06 D'max did a great job pulling that 7,500+ lb plow truck through 10-12 inches of rutted wet snow. Of course the Goodyear Wrangler tires worked great in this deep snow. :)
 
Dad's 05 LLY said:
Sounds like it's time to put a plow on the 06!!!
Click to expand...

Sure is looking that way. Biggest problem right now is that the '06 is my every day driver. Couldn't afford to keep the other car.

I'm reluctant to spend several hundred dollars to fit the '06 for the plow this late in the season. Plus, I would have to get something else to drive. So far we've had two good snow storms, but Michigan weather is so damned fickled it's hard to plan ahead this late in the game.
 
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