usually that means no electicity to the actuator. Gm had a hrness update to the frt actuator... i would start by calling chevy and getting the harness update
File In Section: 4 Drive Axle
Bulletin No.: 76-43-01A
Date: September, 1998
This bulletin is being revised to add information to the Service Procedure, add a new part number, and include schematics. Please discard Corporate Bulletin Number 76-43-01 (SectionXXXXXAxle).
Some owners may comment that the colder the outside temperature is, the longer it takes for the front axle to engage whenXXXXXis selected, or the front axle does not engage.
The front axle engagement actuator is a thermally activated component. Because of this characteristic, the time required for the actuator to completeXXXXXengagement is extended as the temperature drops.
Replace the front axle actuator and include the applicable wiring harness kit. Refer to the Parts Information in order to determine which wiring harness kit is needed.
1996 model trucks with a build date on or after January 2, 1996 are considered as "961". If the build date of the truck is unknown, verify the 3 character "axle code" on the front axle label in order to determine which wire harness to order.
This new actuator uses a motor to engage the front axle and is not affected by temperature. On 1988-93 models with a GVW rating over 8500$, the new actuator cannot be installed and the thermal actuator will remain the service part.
Parts are currently available from GMSPO.
Some owners with actuators that are operating as designed (5-30 seconds engagement time) may choose to upgrade to the fast actuator at their own expense. The fast actuator is a new product enhancement and should not be used to replace actuators that are operating as designed.
For vehicles repaired under warranty, use:
thats what my data shows ill opt out see if anyone else has a better idea....i still thinks its a frty actuator isue if the transfer case engages
Hello my name is XXXXX XXXXX X will be more than happy to assist you.
If you will disconnect the front drive shaft front the transfer case and leave it connected to the front diff. Engage the 4X4 and try to turn the drive shaft by hand. Does the drive shaft still turn with it connected to the front diff?
Sorry for the delay.
will be online for about 8 more hours and off and on tomorrow. Just reply back to this post and the system will send me an email to let me know.
One thing I do need to know, the front diff actuator does it have 2 wires that plug it to it or does it have a cable going to it
All test should be done with the vehicle running and in 4X4.
If the shaft does turn then the Front Diff Actuator is not working
If it does not turn then try to turn the Transfer case out put yoke that connects to the front drive shaft by hand. If it does not turn then 4X4 should be working, If it does turn then let me know and we will go from there.
I missed that info when I was looking over everything that had been done.
That changes things so at this time disregard the test I wanted you to do.
Do you have a test light?
Sorry for the delay the system went down and I lost everything I typed in
You problem should be the Transfer Case Switch. Look on the Transfer Case for a switch that has 3 wires that go to it. Light Blue, Dark Blue, and Brown.
Unplug the connector, take 3 pieces of wire, and incert them in the wire connector slots. Then twist the wires together so all 3 wires are hooked to each other. Now see if the 4X4 works. If it does then the switch is bad.
The switch cost about $15
I also meant to add in make sure the GAUGES 10 Amp fuse is no blown.
What really make this difficult on my end is there are 3 transfer cases and 3 wiring diagrams. none of them tell me which is which, and I cant see your vehicle to verify which transfer case is in it. I know it is not the Auto push button since you stated you have a shifter, so that leave 2 left.
This sensor will be right next to the front drive shaft on the Transfer Case.
If the sensor is there and has 3 wires going to it, then yes that should be the problem.
The sensor allows power to go to the actuator and the bulbs when it is shifted into 4X4.
No one suggested it because they went looking at the correct wire diagram.
Sorry for the delay I was off line on Sunday.
Go to the switch I have you look at, with the key in the on position check and see if you have power at the Brown wire.
If no power then check the 4WD fuse see if the fuse is blown and also test to see if you have power there. If you have power there then you have a open in the wire. If no power then Let me know and I will trace down the power source. Make sure these test are done with the key on.
If there is power and the switch is good then you have a open in the Light Blue wire or a internal problem inside the transfer case.
Fuse #24 is the fuse for theXXXXXfront actuator. This fuse should have power when the key is in the ON position. Here is the Fuse block lay out and wire diagram.
Sorry for the delay, I am in the middle of rebuilding a trans in a Cadilliac.
Do you have a voltmeter?
Go to the Transfer Case Switch unplug it, put the vehicle in 4X4 and test the Brown wire for power with the test light. Does the test light light up? (All Test Should Be Done With the Key ON and In 4X4.)
If yes then plug it back in and probe the Light Blue wire. Does the test light light up?
If yes then to front diff actuator, leave the vehicle in 4X4 and test the Light Blue wire for power. Does the test light light up?
Yes it is the same switch. Now that the switch did not fix it like I thought it would we need to do some test to find out where power is geting to. I don't think the new switch is bad, but it can happen.
Do the test and let me know if you have power at all of these places. If you do then we will move to the next steps.
Leave the Transfer Case Switch Plugged in and put the it in 4X4.
Go to front diff actuator, unplug the connector and test the Light Blue wire for power. Does the test light light up?