No 4 Lo. Despite all the efforts

[Dragojazz]

Hi folks,

I'm reviving my 98 Yukon piece by piece. The latest adventure was to restore the 4WD.

My transfer case was shot, so I bought an upgraded one. I think - Think.. the install was a success, but it wont go into 4Lo. The Service 4WD is now OFF after the replacement.

After pouring over the internet, I realized that my ABS light being on might have interfered with that, so I decided to knock that out first. I got lucky with a replacement sensor - right front wheel, and the ABS light went away.

4 Hi appears to work (after 3 flashes) and 4 Lo flashes 5 times and goes back to 4 Hi. I did not get a neutral indicator until I took out the fuse and and replaced it- now that appears to be functioning. I validated I get into 4 Hi by circling on pavement and getting some small chirps.

There are no more error codes (that I can pull) and no lights on. I'm wondering if theres any next step troubleshooting I have to do. I've read somewhere that the TCCM needs to be reset even after fixing the issue, and that might resolve.

Wondering if there's something I'm missing, or if I can reset the TCCM some other way?

Appreciate the help- thanks!

 

[exp500]

There are error codes, but it takes a hi end scanner/TECH2 to get them.
You could try removing shift electronics assembly from Tcase and manually shifting case to verify that part of it works correctly. Remember position it was in. That would be Home. for reinstall.
There are a few threads here about cleaning the contacts in the rotary switch part of Tcase actuator.
Good luck and keep posting.

 

[Dragojazz]

Thanks. If there are error codes that I can't get to, it might be prudent just to take it to a shop with a scanner. Might save some time.

I might drop the encoder motor and try that manual shift first..

 

[Dragojazz]

So I went the shop route.

They told me it was a binding transfer case encoder motor. Simple enough. I ordered one and replaced it.

I didn't get the results I expected. Where the old one would flash into 2hi- 4hi (but not 4Lo) and pick one and stay, the new one has a solid Neutral, 2HI and 4LO lights and nothing seems to switch back and forth. Those three lights are solid. I did have to manually move the transfer case lever to Neutral with a 15MM wrench. It bolted up fairly easily after that.

I'm at a loss at this point.

 

[Fless]

Is your 4Lo mode commanded like the later models? (tranny in neutral, ignition in run position, slow or no speed, etc.) This is from my '04 with the Auto transfer case NVG246:

 

[Dragojazz]

Yup. Have to be in neutral, slow speed, etc..

I just went out and found that the #2 Fuse was blown. (10 AMP- Transfer Case). I replaced it. It instantly blew again without touching anything. I'm thinking I may have bare wires touching somewhere?

Something may have changed with the encoder motor switch out. This wasn't the behavior with the old motor.

And the research I'm doing says the #2 TC Fuse should be a 20 Amp. Not sure why the 10 Amp was there. Maybe the new motor required the draw and it popped?

 

[Dragojazz]

Wanted to let you guys know- it was the fuse. Replacing it with a 20AMP restored full functionality after the encoder and case replacement. I'm back in business!

Thanks all.

 

[willxfs]

Thanks for the follow up. Glad your all fixed up.