4 Wheel Drive/SUVs: 2000 Oldsmobile bravada

Question
QUESTION: It has smartrac but my 4×4 isn't working back tires spin but front doesn't even try got it stuck &service and light came on but didn't stay on &now keeps blowing act fuse under hood any ideas plz help

ANSWER: Patrick,

The computer controlled NP-136 transfer case uses two speed sensors to sense the difference in speed between the front output shaft and the rear output shaft, and engages the front axle accordingly. These trucks use an "Active On Demand" transfer case. Basically its a normal 4x4 transfer case with a big electrically actuated (by way of a motor) clutch that connects the front prop-shaft (which is being spun by the wheels full time) to the transfer case front output. Its all in the transfer case. I'd check all the fuses and the wire harness to the encoder motor and replace the encoder motor if it has gone bad. It could also be one of the speed sensors is not working and not engaging the AWD. Did you have the PCM scanned for trouble codes? 9 times out of 10 it is the encoder motor.

Carl

---------- FOLLOW-UP ----------

QUESTION: Hey thanks yeah I had it scanned scanner said couldnt communicate with system which made me think beens it was blowing fuses maybe it is actuater on transfercase

Answer
Patrick,
Wow, sorry about the scanner.  Not sure what is going on, but I would be tempted to go to another shop to have it scanned.  
Other than that, you might consider getting a repair manual at your local auto parts store.  They are not real expensive, and have great information on troubleshooting that you can do yourself.

Carl