97 tahoe 4wd switch

[ghilliard]

I have a 97 tahoe 5.7 engine 4x4 - 4wd not working. When I turn the key to start the vehicle all three lights, 2hi, 4hi, 4lo, come on with the rest of the dash lights and then go off after a couple of seconds, that is all three lights on the switch go off. I replaced the switch and problem still exists. What should my next step be to diagnose the problem. I've not been able to find front hub actuators for the 97, only a transfer case motor. could that be the problem? Thanks....

[BiggWaukegan]

Not too sure about your problem. But I also have a 97 tahoe lt with 4wd. Lets see a few pictures.

[ghilliard]

50 views and only 1 reply...1 reply, I might add, which is totally irrevelant....NICE!

I know I'm a newby, so if I've done something wrong, please let me know. Otherwise I would appreciate some help. Thanks.

[GMMerlin]

Originally Posted by ghilliard

50 views and only 1 reply...1 reply, I might add, which is totally irrevelant....NICE!

I know I'm a newby, so if I've done something wrong, please let me know. Otherwise I would appreciate some help. Thanks.

Did you do a search?
Typically if your question has not been answered, there are probally a bunch of threads already started on this subject.

The switch is just a signal to the TCCM.

The New Venture Gear Model NV243 is electronically actuated. The vehicles equipped with this model have no transfer case selector lever. The operator selects 2HI, 4HI, or 4LO by pushing one of three switches mounted on the instrument panel. During normal driving the transfer case is in the 2HI mode. When the transfer case is in 2HI both the 4HI and the 4LO switch circuits are open, and both lights are OFF. When the four-wheel drive has been selected, the four-wheel drive indicator lamp on the switch turns on when the front axle has engaged. The lamp will blink while the front axle is engaging.
The TCCM performs the following functions:
- Receives input signals

- Processes the signal information

- Develops output signals

- Sends the output signal in order to control the shifting of the transfer case

The TCCM receives input signals from the following sources:
- The transfer case shift select buttons

- The NSBU switch on the vehicles with automatic transmissions

- The clutch position switch on the vehicles with manual transmissions

- The vehicle sped sensor calibrator module

- The encoder/motor range and the mode feedback signals

- The diagnostic enable

- The front axle mechanical status signal

In order to ensure the electronic shift system is operating properly, the transfer case control module (TCCM) continually performs diagnostics checks on itself and other parts of the electronic shift system when the ignition switch is in the run position.

[777stickman]

After the lights flash on the switch what happens then? Is the 2HI light on steady? When you select 4HI or 4LO do those lights flash? Did you put a scanner on it for trouble codes?

The more info you post the easier it is to try and help...........Steve

[MT-2500]

Originally Posted by ghilliard

50 views and only 1 reply...1 reply, I might add, which is totally irrevelant....NICE!

I know I'm a newby, so if I've done something wrong, please let me know. Otherwise I would appreciate some help. Thanks.

Well you can not expect everyone to be a expert on 4X4 problems.
Be glad they looked at your post.
50 views is good.
As said a search would help you find a lot of info already posted on it.
But on that one you need to ground pin no. 13 on your diagnostic plug in and count the flashes.
Post back the no of flashes.
MT

[ghilliard]

Thank you all. Yes I have searched and the only results I have found mention front hub actuators.

The 2HI light does not stay on and pushing any of the three switches does nothing. When I turn the key, all three lights on the switch come on for about a second and then all three lights go off and pushing any of the buttons does nothing.

No, I have not put scanner on it; I don't have one. I may take it to AutoZone and have them put their scanner on it.

What about the Transfer Case Shift Motor?

[ghilliard]

Originally Posted by MT-2500

But on that one you need to ground pin no. 13 on your diagnostic plug in and count the flashes.
Post back the no of flashes.
MT

Thank you for trying to help, but I'm not sure how to do that.

[MT-2500]

Originally Posted by ghilliard

Thank you for trying to help, but I'm not sure how to do that.

A good search shouls have got you some good info.
Other people and I have posted on it quite a few times.
Just like pulling codes on older GM by grounding the right pins on diagnostic connector.
But.
Pin 13 ground on works on certain years like yours.
Here is a picture of the diagnostic plug showing pin 13.
Just ground it and turn key on and watch the shilft lights for flashes.
Count flashes and post back what it does.
http://www.troublecodes.net/OBD2/
Or run it by a repair shop and get them to put a transmission/transfer case/ engine capable scanner on it.
Lot better than throwing parts at it.
MT

[ghilliard]

Originally Posted by MT-2500

Pin 13 ground on works on certain years like yours.
Here is a picture of the diagnostic plug showing pin 13.
Just ground it and turn key on and watch the shilft lights for flashes.
Count flashes and post back what it does.
MT

I grounded pin 13 and turned the key. The shift lights flash continuously every 3 seconds. I counted up to 20 flashes before I turned it off, so it appears to be continuous.

[MT-2500]

Originally Posted by ghilliard

I grounded pin 13 and turned the key. The shift lights flash continuously every 3 seconds. I counted up to 20 flashes before I turned it off, so it appears to be continuous.

You should only get 4 different codes.
A code 1 or 2 or 3 or 4.
Try clearing codes and recheck.
If that does not work you need to get a repair shop check it out on a transmission /engine capable scanner.
MT

[ghilliard]

Originally Posted by MT-2500

You should only get 4 different codes.
A code 1 or 2 or 3 or 4.
Try clearing codes and recheck.
MT

After checking several more times, I believe I am getting a code 1 that repeats every 3 seconds. One test gave me a code 2 that repeated every three seconds. I then disconnected the battery for about a minute to clear the codes and rechecked, and I'm getting a code 1.

[MT-2500]

Here you go.
Good Luck.
MT
http://members.troublecodes.net/crunch/97taho.pdf

[GMMerlin]

The transfer case shift control module normally has battery voltage supplied to it at all times through the battery positive voltage circuit (CKT 40). When the ignition is ON, the transfer case shift control module conducts a self-test to determine if it retains the same memory it had when the ignition was last turned OFF. This self-test indicates whether the RAM standby power supply to the transfer case shift control module pin C6 was interrupted, which would result in clearing DTC's from memory. If the self-test fails the transfer case shift control module sets DTC 001.

Important: This code can get set falsely due to the improper clearing of DTCs or replacement of a blown CTSY LP fuse.
This step inspects the CTSY LP fuse for an open.

test the battery positive voltage circuit (CKT 40) for an open or high resistance.

recheck the CTSY LP fuse for an open

tests the battery positive voltage circuit (CKT 40) for a short to ground.

[ghilliard]

Thanks MT and GM. I have found the information you have given me to be very helpful. I will run some more tests and post back what I find.

Thanks again
ghilliard