Rear Differential Lock Coil Shorted
 

Hello all! I've not been here much, as I don't own an H2, but my boss does. I'm trying to find out some information for him (and me if I end up helping fix this issue he's having).

He has a 2005 H2 and has the Service 4WD message on. He just got it back from the Hummer shop and they said that the "Rear Diff Lock Coil Shorted." They quoted him over $1,300 to fix this. They eventually went down to about $980+.

Is this a difficult fix? I was hoping it was more of the actuator and not inside the diff, but doesnt seem that way.

Is there any other information that you need from me in order to diagnose/fix the issue?

Thank you for any help you members can provide!

Sucks!!!!

It's a $200 part but, you have to pull the differential out to change it.

It's a decent amount of work, especially at Garage prices.


Only thing you can do to make sure it's not the wiring or the switch is turn the locker on and back-probe the wires at the connector @ the rear axle.

gets 12v.

What do you mean by back probe? Check that its getting proper voltage?

I do hear the motor when the switch is hit.

Any more thoughts?

Any special tools for removing the internal differential parts in order to change the coil?

I am going to change mine out soon, so I will get back to you after it is done. If it is shorted to ground, I would say it is bad...

I would unhook the wires right where they enter the diff and do an ohm meter check to ground and across the two wires. should be no ground and a low but not direct short across the wires. maybe an ohm or 2-3.
the coil looks like a flat donut with two wires. unfortunately the entire rear end must be dismantled. very difficult and critical assm.
be absolutely sure its not damaged wires outside where you can fix!

Just an FYI/UPDATE:

After posting here and more digging, a buddy and I decided we would just change it out. Was doing more research to find out what gaskets and such I would need (diff cover) and went out to the truck to count the bolts (14 i think). I figured, let me see where these wires come out and connect to the actuator. Well, I found the plug and pulled it apart easily. I thought, that aint right. I put it back together and pulled it apart very easily several times. There was no clip holding the connector together ( i guess it broke off). Well, I hooked it back up and didnt think anymore of it.

About an hour later my boss and I had to leave for a meeting. We get in the H2 and get to rolling and he says to me, the service warning is not there. I said, hmm...all I did was unplug and replug it a few times because the clip was broken off.

So we drive (about 1-2 miles) to the meeting and still no service warning. So we throw it in neutral and change it to all the different settings and it works! In all the settings! 4HI, 4LO & Locked! We cant believe it!

The next morning he calls the dealer and they say, yeah, we noticed that the clip was broken on the connector, but expect the service warning to come back.

My boss drove that thing up until Friday last week when he drove it to Dallas and traded it in (was his plan all along) and that service warning never came back on. All I did was put a zip tie around the connector so that it didnt come loose again.

I know that dealer was trying to get over on him. It's no wonder why they came down on the price over $300.

So, moral of the story 1) dont trust the stealer & 2) exhaust ALL possibilities before tearing into a differential!

Thanks guys!