Posted by Dimsdale on July 18, 03 at 12:06:29:
In Reply to: NP Transfer Case posted by FELIX on July 17, 03 at 10:10:51:
I have a 99 Suburban with Autotrac, and I had the clunk problem which was fixed with the AT II fluid. There is also a more recent upgrade for the output yoke, one that is nickel plated. Not sure what that is supposed to do.
My guess is that the switch somehow failed, and you might have been in one of the no auto 4WD modes and bound up the system enough to break something.
As a preventative measure, I run in AUTO at least once a month to exercise the the front axle engagement solenoid, encoder motor (does the shifting) and distribute the lube in the differentials and the transfer case (even though it has its own internal oil pump). Kind of like what they used recommend for the hub lock type axles. I try to use all the modes at least once a month as well. One of the few advantages of a dirt driveway. I would imagine that the switch contacts can get a thin layer of corrosion from disuse than might be fixable with some TV tuner cleaning fluid or some vigorous use. You might play with the old switch before discarding it.
: '99 K2500 6.5 - While doing an oil change in spring '02 I notice a small weep of pink fluid from the transfer case fill plug. I tightened it up a bit and mentioned it when I brought it to the dealer for service on another matter. They replaced the drain plug and added fluid. Another o/c and I saw the same thing reappear, now worse. I took it to the dealer and they said there was 'nothing wrong'. Shortly afterwards the transfer case began making noises during coasting or light accel. I checked the fluid level and it was fine. Altho bought new - I was already over miles on warranty when it failed loudly and completely. This is the NP 'Auto trac' and only available thru GMC and replacement ran $2k.
: Prior to going on vacation last year had all the fluids (tranny/oil/case) flushed and checked at another (Chevy) dealer who said I had the wrong fluid in the (new) case - should be 'blue' and not pink.
: I checked on ALLDATA and see TSB's for the drain plug and the fluid. At the very least if wrong fluid is used there should be a recall.
: Now - a year and some 40k miles later - the 4wd switch is not working correctly and it is difficult and sometime impossible to come out of 4wd low into 4hi or 2wd unless I let the vehicle rest overnite and then the relay clicks / solenoids slide and everything is normal (no 'check 4wd light').
: I do not off road but live on a nasty dirt road and use the 4hi for snow/slush and the 4wd low to climb
: my ramps for oil changes.
: What do you think?