NEED HELP Stuck in 4hi, but not

eightshot627

Original poster
Member
Aug 8, 2012
79
I'm over at the in-laws and noticed the selector switch was reading 4hi. The switch is in 2hi. It doesn't feel like it is in 4wd. The switch blinks 2hi when I put the switch to 4hi then back to 2hi. I don't hear whirling sounds either front or middle. I have already replaced the tcm with a 2003. I also tried pulling both fuses and swapping them with spares. When selected it will go to auto but when try to put it in 4lo or 2 hi it flashes there and then quits and stays in 4hi. No service 4 wheel drive light. I have been using 4wd a lot the last 3 weeks without issue.

Any ideas that I can try without tools or test equipment?

Thanks,
Walt
 

mrrsm

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Sir ffeJ

Member
Dec 1, 2011
543
The contacts on the switch can get dirty and give false readings. Try cleaning the contacts by rotating the switch several times (with ignition off)

Perhaps also try a restart by disconnecting the battery for 30mins. I know the fuses usually do that but I'm just thinking of anything right now.
If that's a no go, there isn't much you can do without tools right now.
 
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eightshot627

Original poster
Member
Aug 8, 2012
79
Both done before I posted. I believe the switch works because it flashes like it's trying to get there but gives up
 

Sir ffeJ

Member
Dec 1, 2011
543
Can you elaborate on the 2003 TCM you mentioned replacing. What was the reason for that?
Perhaps the replacement has failed?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
The original 2002 TCM had a known defect and would fail on a regular basis. 2003+ did not have this flaw.
 

eightshot627

Original poster
Member
Aug 8, 2012
79
In 2015 i was troubleshooting and got the 2003 TCCM. As it turns out my TCCM had already been replaced. The fault then was the encoder motor. I think more specific the position sensor in it.

Now that I'm home the darn thing started working again this morning. At least it went to 2hi and then 4hi and back to 2hi when commanded. Worked this evening too. Not sure the front really engaged but I'll check that out.
 

eightshot627

Original poster
Member
Aug 8, 2012
79
Ok now it will only go to 4hi or auto. No 2hi or 4lo. I heard a high pitch wine at the transfer case encoder but the front actuator was silent. I pulled it and it looked like it was pushed out. It pushes itself out when I took out the bolts. With the actuator removed and the front on jack stands it would free wheel the right and using the end of a ratchet push the fork in and turn both from the right. Releasing the fork it would unlock. Returning the actuator in place would lock up the front.

Do the front actuator fail engaged?
 

eightshot627

Original poster
Member
Aug 8, 2012
79
Ok she is finally fixed. She was stuck in 4wd. It would go to auto or 4 hi but no other and when you tried shifting to 2hi or 4lo she would blink where commanded and would light 4hi. No noise from the front actuator and the transfer case encoder motor just hummed like it was bound. The front actuator failed extended. With the new front actuator installed the transfer case still hummed but still the same at the switch. I thought the transfer case was f!@ed but replacing the encoder motor worked. Full functioning! Now to change the xfer case fluid.
 

mrrsm

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Oct 22, 2015
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Tampa Bay Area
FWIW Brother... Have a look at this link that has the GM Paper Manual Images of ALL the Ground-Bonding Strap Wires... for anything sketchy... I'm wondering if the Databus Splice Pack Ground along the Passenger Side Center Console might be the culprit ...with a clean-up of the Ground as described in @MAY03LT 's Video:

https://gmtnation.com/forums/threads/electrical-ground-locations.15491/

 

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