How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Real World Tech Your Own Question
Real World Tech
Real World Tech, ASE Master Auto Technician
Category: Chevy
Satisfied Customers: 77
Experience:  12 years experience with Chevrolet diagnostics and repair.
Type Your Chevy Question Here...
Real World Tech is online now
A new question is answered every 9 seconds

1995 chevrolet: z71..front diff actuator switch was..4wd..didnt work

This answer was rated:

just bought a 1995 chevrolet z71 for a hunting truck. was told that front diff actuator switch was bad and 4wd didnt work. i ordered one off of ebay. It came with factory clip. The actuator had been hardwired with butt connectors. The stock switch had green and black wires, the new one had 2 black wires. I hard wired it back up and nothing. I tried swapping the wires to be sure that i had it wired correctly.........nothing. The transfer case seems to be shifting smoothly but front wheels wont enagage. The orange light on the shifter won't light up either. I have checked the fuse on the dash and it is fine. Any Ideas? Please help! hunting season is a few weeks away and I'm not in business!

First off, you need to make sure that you have power on the 4wd fuse with the key on. Check this with a test light or a volt meter.

There is a switch on the top left of the transfer case.

It has three wires and looks like this.

Brown wire needs to have 12volts in the run position.
and the light blue wire needs to be hot when you engage the transfer case.

If the brown wire is hot, and the blue isn't when you engage the 4wd, you will need a new switch.

If the brown wire doesn't have power with the key on, you have a problem with the feed circuit from the 4wd fuse.

If you do have power on the light blue wire when the transfer case is engaged, check for power on the light blue wire at the actuator on the front differential.

If you don't have power there, you have a problem with the light blue wire from the switch on the x-fer case to the actuator.

If you have power on the light blue wire on the actuator when it is engaged, and ground on the black wire at the actuator, the actuator is bad, or the front differential stopping the actuator from extending, and will need to be dismantled and inspected.

Hope this helps, and let me know how it goes!
Customer: replied 7 years ago.
fuse is good. I think i have foune the switch on the transfer case. There is a wiring clip that goes into this switch with 3 wires. a definate brown and blue blue and maybe white or light grey. (it exrtremely dirt under there) lol. should i be checking voltage on this clip going into the transfer case? If so, I am hot on the brown but not hot on blue when 4x4 is engaged. Does this make sense?
If the connector is plugged in when you are checking this, at the back of the connector, the switch is bad.

It costs around $20 at napa!
Customer: replied 7 years ago.

i unplugged the connector to check for voltage because its such a bear to get to while hook to transfer case. if i plug the connector in, where do i check voltage. it seems like i'm checking voltage befor it gets to the switch.`


You are going to need to check for voltage with the switch plugged in, as this is how it gets its signal when the x-fer case is engaged.

You could skip this step for now, and check for voltage directly at the blue wire on the actuator on the front axle.

If you have power there with the x-fer case engaged, you know that the switch in the x-fer case is good.

Let me know.
Customer: replied 7 years ago.

let me check. be right back


Customer: replied 7 years ago.

ignition is on, tried transfer case in 4 high and 4 low with tranny in nuetral and drive while in 4wd. no voltage at blue wire at actuator


Ok, hate to tell you this, but you're gonna have to check for power at the switch on the x-fer case.

Maybe it would be more feasible to just go ahead and change the switch?

Here is the part number at Napa. BK(NNN) NNN-NNNN It costs around $20.

At this point, it is either the switch, or a bad wire between the switch and the actuator.

Lemme know!
Customer: replied 7 years ago.

k, i'm running to advanced napa is closed now. they should be able to cross ref number right? does the switch just screw out of xfer case? shouldnt take me but a few to get back. if they cant cross ref., what exactly is this called?


Its called the transfer case switch. mounted in the transfer case. three wire.

And they should be able to cross the number.

I'll be here..
Customer: replied 7 years ago.

callin now. everybady says they dont know unless i bring it in. does this screw right out of the tranfer case?


It is called a transfer case select switch.

Yes it screws right out of the transfer case

The Dorman part number is XXXXX

The Oreilly part number is XXXXX made by Borg Warner
Hope this helps
Customer: replied 7 years ago.

you've been such a great help. if i accept the previous anwers you sent, will it end our contact? Advanced and auto zone need to order it . I'm hoping that napa will have it in stock but i can't check till monday. (my luck) how can i get back in touch with you?


You can accept the answer here, and the question will stay open. Just reply here and I will get it.
Customer: replied 7 years ago.
thanks sooooooooooooooooo much! i be sure to get back with you, but like i said, it will be next week. Laughing - one more thing, the new front actuator has 2 black wires only and no reference on which goes to the factory blu wire leaving the transfer case. the yo-yo that i bought the truck from cut the clips so i had to hard wire the actuator with butt connectors. if i have it hooked up backwards will it just blow a fuse? then i can switch them back around?
No, it doesn't matter which way you have them wired.

Either way will work, and not blow any fuses.Wink
Real World Tech and 5 other Chevy Specialists are ready to help you
Customer: replied 7 years ago.

I can not thank you enough for helping me fix my 4wd. I got the part from NAPA for $22.00, replaced it, and in 10 minutes I was in 4WD. I couldn't believe how easy it was. The light on the shifter still doesn't work, but thats not my concern. Thanks so much again for the help. You have been an asset to me.