4wd issues

[ginas930]

Ok I need alot of help very desperate here. I have a 2000 Chevy Blazer and I have been having some problems with my 4wd. What it does is all the lights on the dash switch are on as well as the service 4wd light. The car feels like it is gonna stall while driving but only for the first 30 miles after that it drives normally. Now I have replaced the transfer switch on the dashboard and that wasn't the problem, I replaced the 4wd motor but found out that wasn't the problem either so I put the old one back in. I also checked all the fluids levels and they are fine.
Any other suggestions on what the problem may be?

[JaVeRo]

With the wheel blocked and the engine running, put it in 4wd and try turning the front driveshaft. If it is locked then the problem is with the front axle. Since you are having problems with it trying to stall I would guess it to be a vacuum problem.

There is a vacuum switch on top of the transfer case with a vacuum line going to the actuator under the battery. You will have to pull the battery tray to get to the actuator.

The vacuum actuator is a diaphram that pulls a cable to engage the front axle when vacuum is applied. If I had to guess I would say the diaphram has a tear in it.

If the front driveshaft still turns free after you push the 4hi or 4lo button then the problem is with the transfer case. I'm not much help there.

James

[muddog321]

True for the 3 button case NP233 but if an LT with 4 button theres a solenoid on the firewall for that. Yep, check vac first and then pull the battery cable OR the ATC and 4wd fuse for 30 mins to reset the TCCM.

[ginas930]

Muddog thats is my set up with the 4 button, thanks for the info but I check all this already and it was none of the above. I believe the problem is from the switch to the "control box or some sort of control that tells the motor on the trainy to switch" is there a such thing as a control box that tells the trainy to switch??

[Jimmy58]

ginas930, first of all to answer your question yes there is a control modual for your transfer case. It is on the passenger side kick panel. If your lights are lit at the same time and the dash light is on the first thing I would do is to go to a tranny shop and have the codes read from the tcscm and then procede from there. Most shops will charge a modest fee for this service and some shops wont have the right scanner to read them. I would avoid the dealer as I have found them to be mostly useless. After you get the codes you can find what the codes mean on the web... ALLDATADIY. com being one of many out there. Just from your explanation it sounds like the control modual is toast but that is just a guess. I just went through the whole system on a 99 so am prity up to date on the system.
Is the front axle locked or unlocked? Do you have vacuum through the switch on the firewall? if you do the front axle will ( or should be) locked. Not good to drive on dry pavement with the front axle locked. You have 2 speed sensors on the transfer case, one for rear output speed and one for front output speed. These have to match to get a shift.
One more thing I found out. your transfer case will only try to shift one time per ignition key cycle. As muddog321 has said, pull the 4wd fuse in the ip fuse panel and the ATC fuse in the underhood panel and let it set for at least 30 min. Put your fuses back in and try it. Let us know
Nick