4wd problems

[randymott]

i have a 2003 chevy tahoe, 4wd willl shift to 4 hi but 4 low just blinks.then goes back to 4 hi.what could cause this?

 

[MO Viet Vet]

Check all connections at the encoder motor and anywhere in between. But I have heard that lots of times this is related to a bad switch. Not always but lots. Recently another member here had the same problem and he was told that for sure it is the switch. He replaced the switch. Still doing it. Checked connections and found dirty/loose connection and fixed it.

 

[SteveCV]

I have a 2005 Tahoe with 100K+ miles on it. The truck has been virtually trouble free EXCEPT the 4WD. Without going back and looking at the receipts, over the years I recall having an encoder motor sensor, actuator, and servo(?) fail. The symptoms have ranged from not engaging 4H (but would engage 4L) to "Service 4WD" being displayed to not being able to engage 4WD at all. Each repair has been successful and 4WD has worked flawlessly for a number of years between problems. So far it has not needed a switch. It may be next...

 

[MO Viet Vet]

It may all come down to needing expensive parts but always check the less expensive wiring and connections first. I always check the basics first instead of throwing parts at it but as I said it may still need parts.

 

[SteveCV]

yup

I totally agree. Check connections and less expensive things first. I learned long ago that when I threw parts at a problem without a genuine diagnosis I usually got several new parts I didn't need before I landed on the right one.

I confess to taking mine in these days to someone who can properly diagnose it (in particular the 4WD) and just have them fix it. It's cost me a little more (or more than a little more) but for this particular system I've been happy to have someone else fix it and so far, fix it right the first time.

My point was only that it seems to me this part of my Tahoe is more problematic than the rest of the truck. Many of the "little" parts like sensors and servos (as compared to the transfer case, for example) seem to be not terribly durable. And no, I probably wouldn't just replace the switch unless I could come up with some evidence that it actually was bad...