Mechanics

CHEVY 4X4

1994 Chevrolet Truck • 6 cylinder 4WD Manual • 250,000 miles

I have a 1994 chevy w/t 1500. It has automatic hubs. The hubs will not lock in. The truck has a seperate shifter for the 4x4. When I engage the 4wheel drive nothing happens. Ive checked voltage to the actuater and getting 12volts. I replaced the actuater and still no luck. Is there anything else I can check?
Jerry
Avatar
Jmorrison44
December 30, 2010.



Attached is a chart for possible causes of 4WD not engaging.

What is the transfer case model identification?


KHLow2008
Dec 31, 2010.
Some things I forgot to mention. The transfer case was rebuilt about 100,000 miles ago. Of that mileage, its only been driven maybe 1000 miles in 4 wheel drive. I have driven in 2h 4L and 4H at various speeds and experience no weird noises or vibrations. Just seems like the front hubs refuse to lock in. Should I get the truck on a lift and make sure my front drive shaft is spining when I engage the 4wheel drive? Also a fuse should be ruled out since Im getting 12volts out of the actuator plug, correct?


Tiny
Jmorrison44
Jan 3, 2011.
Also the 4x4 indicator light has never come on since the malfuction. Do you know where the sensors are for the indicator light? Axle? Transfer case? Both?
I will try and get the model identification for the transfer case soon.


Tiny
Jmorrison44
Jan 3, 2011.
The transfer case switch is located on left frot of transfer case.

Here are the diagnostic procedures.

4WD Will Not Engage

1. Test power to transfer case switch. With ignition on, connect test light to ground and backprobe Brown wire terminal at transfer case switch connector. Test light should light. If so, proceed to next step. If not, inspect 25-amp 4WD fuse in fuse block. If fuse is okay, attach test light to ground and backprobe Pink/White terminal at convenience center. Test light should light. If so, repair open in Brown wire between convenience center and transfer case switch. If not, repair open in Pink/White wire between convenience center and 4WD fuse in fuse block.

2. Test transfer case switch. With transfer case shift selector in 4WD position and ignition on, attach test light to ground and backprobe Light Blue wire terminal at transfer case switch. Test light should light. If so, proceed to next step. If not, replace transfer case switch.

NOTE: Remainder of transfer case electronic testing and diagnosis is performed with transfer case gear selector in 4WD position and ignition on.

3. Test front axle solenoid power circuit. Attach test light to ground and backprobe Light Blue wire terminal of disconnected front axle solenoid. Test light should light. If so, proceed to next step. If not, repair open in Light Blue wire between front axle solenoid and transfer case switch.

4. Test front axle solenoid. Attach test light between Light Blue wire terminal and Black wire terminal of connected front axle solenoid. If test light lights, replace front axle solenoid and proceed to next step. If test light does not light, repair open in Black wire between front axle solenoid and ground. If no opens in circuit are found, replace transfer case relay.


KHLow2008
Jan 4, 2011.