2002 Yukon XL Won't Shift into 4HI or HLO
My 2002 Yukon is stuck in 2HI and the cab switch just blinks when I try to
switch into 4Hi, 4Lo, or Auto. I don't get the clunk. I've already replaced the
front actuator as well as the switch in the cab. I am getting 12V to the
actuator although I can't say for sure that it's engaging. The 4WD fuse also
I have now turned my attention to the transfer case motor. I am getting 5
volts to the green and brown/white going to the motor and the ground seems
to be find as well. I tried to backprobe the brown/white wire so I could test for
a voltage difference when I switch into 4Hi or 4Lo. What happens however is
that my backprobe reads 5 Volt when the connector is unplugged from the
motor but when I attached the wiring harness to the motor and test voltage
(grounding to the battery) I can zero. I have no idea what this means, might
there be a short in the motor?
I appreciate any insights!!
Maybe the transfer case is the problem.
That's signal voltage from the GEM so it knows what position the shift motor is in, 4HI, 4LO, 2WD or AUTO. Transfercase shift motors are a common failure on just about everyone that uses electronic shifting. Sometimes you can get the motor to run if you tap it with a small hammer (or rock it stuck off road) while someone hold the 4HI button and it might run a time or two, I had to replace that motor on both a Ford Bronco and a Chevy Tahoe that I have owned.
Thank you, I'll get under it again and see if tapping changes things.
I tried tapping the shift motor and it didn't change anything. Before I replaced the shift motor I shifted it to N successfully which was a good sign? Regardless, I replaced the motor and seemed to successfully shift into 4HI once afterwords, but pretty quickly something happened and the Service 4WD light came on. Now I don't even get an indicator light on the button panel. I am guessing I have a more serious problem?
You might want to check the harness right where it comes out of the floor, I have seen a few rigs that have had to much wire flex and caused intermittent connection problem or a bad ground supply, if it's not there then you should take it to a shop you trust, tell them what you have done so far. Who knows it could just be a bad relay.
Thank you tennisshoes. I replaced all the brake lines a few months ago and it's possible I disturbed the wiring harness. I'll take a look.