Fanuc5

96 Tahoe 4WD not engaging

Hello to all.

I have a 1996 Chevy Tahoe 2door 4WD, with the 5.7lt vortec. This vehicle has over 193,000 miles on the original drive train. I do normal maintenance.

i.e. change the rear, front, and transfer case lube every 20,000 miles. 3000 miles for the oil.

I have not used my 4WD in quite some time, the other day it snowed in St. Louis and I engaged my 4WD, the first corner I went around… WOW!! The backend slid away from me. Its not that I didn’t like sliding the backend around, he he, the problem is that the front axles never engaged.

The transfer case as far as I can tell is a manually operated one. I only have a lever in side the cab of the truck to shift it in to 4WD-HI or LOW. I can't find any electronic equipment on the transfer case. The front axle does however have two electrical items on it. What function they have I couldn't tell you.

So here is what I did when I got home. I pulled the rear drive shaft. Put the front up on some stands, and then engaged the 4WD. I then manual turned the front shaft, this turned without a problem and it also turned the rear yoke, but it did not turn the front half shafts. Is there a know problem on the 96 Tahoe’s front axle or is it one of the electrical items on the axle itself, that prevent it from engaging

Oh and I did check the fuses in the cab of the truck, and I didn’t have any problems with them. But I did have a positive battery post corrosion problem awhile back, but I have since replaced the cable and battery.

Thanks for any help that’s you could give me.

John Peterman
St. Louis

Fanuc5

OK...

I took off for lunch today and went down to the local dealer. I sat next to the guy at the parts counter, as we looked at the exploded view of the front drive axle. It turns out the electronic items I found on my axel are in fact an actuator and a 4WD engaged sensor. The dealer told me that part was re-designed and the new part came with a wiring harness that needed to be installed. Basically all that is involed is hooking up a power wire. I installed it and all is well. Total job time was about 35min.

Well that’s it… If anyone else is having this problem I hope this helps…

__________________
Thanks

John Peterman
St. Louis, MO

94 Z71 Blazer

Go non-electric. Here's the link....

http://www.drivetrain.com/4x4PosiLock.html

Fanuc5

I'm posting some email(s) that went back and forth in hopes it may help someone else.... Names have been changed to protect the innocent.

JMP
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----- Original Message -----
From: martin
To: Fanuc5
Sent: Sunday, December 20, 2003 3:12 PM
Subject: 1996 Chevy Tahoe 4wd wire problem...

I have the same problem. That brown wire. Were is it going? Power to the battery or to a fuse ???
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----- Reply to Original Message -----
From: Fanuc5
To: martin
Sent: Sunday, December 21, 2003 11:46 PM
Subject: 1996 Chevy Tahoe 4wd wire problem...


Hello,

I ran the wire to the main wiring harness fuse block point. It is up by the trucks computer on the right hand side (when facing the engine). If you follow the battery wire up and over the fan shroud and up the right hand side fender you will find the attachment point. (I ran the wire in with the batter cable cover to hide it) The attachment point has a 10mm nut holding it to a bolt. I went to a local auto parts store and bought an inline fuse (15amp), and put it in-between the power and the wire going to the actuator. In all it took me about 35-45 min to wire it in. It took longer for the soldering iron to heat up.

I hope this helps...

JMP
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----- Original Message -----
From: martin
To: Fanuc5
Sent: Monday, December 22, 2003 8:47 PM
Subject: Re: 1996 Chevy Tahoe 4wd wire problem...


HI
Sorry, did you only replace the actuator or did you replace any sensor(s)?

Because I have done the exact same thing, the same way, and I still get nothing.

Are there any relay(s) or is there any sensor(s) in the transfer case ?????
Thank you for you HELP

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----- Reply to Original Message -----
From: Fanuc5
To: martin
Sent: Monday, December 29, 2003 1:50 PM
Subject: Re: 1996 Chevy Tahoe 4wd wire problem...


Have you checked fuse number 24 in the cab of the truck? Also there are two sensors one in the transfer case, and one in the front axle.

Here is what I would do:

1. Check the fuse (number 24 on my 1996)

2. Find the sensor in the front axle and remove the plug, put a wire in the openings of the connectors to create a short on the sensor plug. This is simulating that the sensor has engaged.
What should happen: The 4WD light on the manual stick should light up.

3. Do the same thing as number 2 but for the transfer case’s sensor.
What should happen: The new actuator should start to engage and the 4WD light on the manual stick should light up (if the axle sensor is working.)

Hope this helps.

JMP

Oh ps, on some of the manual 4WD system the car or drive train has to be moving forward to engage.
__________________________________________________ ___________


----- Original Message -----
From: martin
To: Fanuc5
Sent: Monday, December 29, 2003 7:54 PM
Subject: Re: 1996 Chevy Tahoe 4wd wire problem...

Thank you for you help !!!!
The transfer case sensor was bad and the plug for the sensor was bad also. I replaced both, and now it is working great!
Once again thank you. You have helped me save a lot of $$$$

__________________
Thanks

John Peterman
St. Louis, MO