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GM Tech (Cam)
GM Tech (Cam), GMC Mechanic
Category: GM
Satisfied Customers: 5785
Experience:  GM Grand Master Technician 2007. 14 years experience.
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2005 hummer locked in 4 wheel Both front and rear

Customer Question

2005 hummer locked in 4 wheel hi. Both front and rear differentials will not release. Buttons blink as before. Turns hard.
JA: How many miles are on the car? Has this ever happened before?
Customer: 230,000. No. Went right into 4 wheel when button pushed.
JA: What is the model of your '05 Hummer?
Customer: H2
JA: Are you fixing your H2 yourself? What have you tried so far?
Customer: Just got home. Will check for electrical cause both difs are locked. I dont think 2 actuators can go bad at same time. Is actuator on the transfer case only for high and low?
JA: Anything else you want the mechanic to know before I connect you?
Customer: If electrical, then can I release the posi on thd differentials by feeding 12 volts to the wires when disconnected from the main harness?
Submitted: 8 months ago.
Category: GM
Expert:  Mike S. replied 8 months ago.

Hi, I am Mike, welcome. I'm reviewing your question.

Expert:  Mike S. replied 8 months ago.

Do you have a scan tool?

Customer: replied 8 months ago.
No. Disconnected actuator harness. Checked actuator with 12 volts. Motor turns fine in both directions and releases the front diff. The rear seems to be locked. Hopps on a tight turn. Is there an actuator for the rear? Why wont the button release the front all the way? Does it adjust?
Expert:  Mike S. replied 8 months ago.

When you press any other position on the transfer case switch other than the one it's tuck in now, 4 high, does the switch light flash indicating that the transfer case module has received the signal?

Expert:  Mike S. replied 8 months ago.

As you can see just about any troubleshooting procedure that I have starts out with the use of a scan tool.

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