Thanks. I left that gonger out. I agree on keeping things stock for the most part. I'm a purist that way but those annoying door gongers and buzzers aggravate the voices in my head. I disabled the one in my pickup truck and have removed this one with no apparent side effects. I will keep it though so I can re-install it if I need to.

And I know that if there's no pictures, it didn't happen so here's one I took after I gave it it's first bath in at least 15 years. Is the paint a common issue with these things? It's not quite as clean as it looks, it has rocker panel and rear fender rust.

 

And on to my next problem. The truck ran well when parked, which was a year or so ago. It's making some kind of a whine now on deceleration. It almost sounds like a fire truck. It whines then it clunks and the whine subsides for a while. When it clunks, it can be felt throughout the vehicle. I checked the drive shaft and it feels tight. What would cause this problem? The transmission seems to be working find and it seems to do it in 2 and 4WD.

 

Whining is typical of a bearing going bad. The clunking could be a U- Joint going bad. You have to determine is the noise in the engine or in the driveline. Driveline clunk and whine could be in the diff. (Pinion Bearing), Clunk could be due to slop in the axles. Pinion bearing is not that difficult.to replace. Pulling the axles and removing the chunk is time consuming but not hard. It might be worth it to see if a shop can put it on a lift to pin point the source.

 

Could I gain any insight by dropping the drive shaft and running on the front drive? The shop I use is usually a few weeks out and I can get it up on jackstands easy enough.

 

I do not know. I have limited knowledge on 4WD Systems. I do have a 2000 GMC AWD/4WD Jimmy. The only problem I have had is the shift motor has gone bad more than once.

 

I was talking to a local mechanic and he tells me that the front axle locks into 4WD with vacuum. Does this sound right? Any tips on how to trace those vacuum lines?

 

OK, it does in fact seem like a vacuum issue. I can see vacuum lines run up over the top of the transfer case and the light on the shifter comes on and goes off with use of the gas pedal. The truck is also running with a slight miss. The kind of miss you get when there is a vacuum leak. Does anyone have a vacuum schematic of this thing?

Thanks,
Mark

 

I found some hoses topside in bad shape and one with a small hole in it so that's a start. What does that thing under the battery do? It has a cable coming in and one vacuum hose attached. It's a plunger of some sort, similar to the one for the cruise control up top but without the vacuum pump.

 

On the cruise control vacuum pump. Is there a way to test it to verify that it's working?

 

Is the Cruise Control mounted on the fender with a vacuum hose and electrical connector? You can test the vacuum side with a vacuum pump and apply vacuum directly to the Cruise control unit. It should hold vacuum without leaking. The vacuum hose from the cruise control goes a brake pedal switch that holds vacuum until you press the brake pedal. Apply vacuum to the hose from the cruise control side and it should hold vacuum until the brake pedal is pressed. The failure is most likely a bad vacuum hose or a leaking diaphragm inside the cruise control unit. Or the adjustment of the brake pedal switch.