98 Blazer 4x4 switch does not light

[munck]

Hi, I have a 98 S-10 Blazer with the push button 4x4. The switch does not light in any of the positions. I hooked my snap on scanner to the vehicle and it says it has no communication. Has any one incountered this before. I'm thinking the transfercase module is bad, but it may also be the switch itself?? Also is the module on the Transfer case itself? Thanks for your help!

[Turbocpe]

There are 3 fuses.

One for the illumination (fuse number 5) in the fuse block panel on the dash side.

One 10AMP power fuse (number 15) in the fuse block panel on the dash side.

One 20AMP fuse in the underhood fuse panel.

If each of those are fine, then tell us this. When you first turn the key to ON, does any or all of the 3 lights blink once then shut off? Or do they not turn on at that time?

Forgot to add that the module is behind the passenger kickpanel.

[BlazerLT]

You hearing any clicking from the glove compartment when you push them?

[munck]

No blown fuses. The lights do not come on ever. Thanks!

[BlazerLT]

Hear and clicking?

[sharky2002]

Hey,
I hear the clicking behind the kick panel but it stays in 2 wheel unless I disconnect the battery then when connected again it tries to go into 4 then quits and stays in 2. Push the 4x4 buttons and all you hear is 1 click behind the kick panel.
Stumped....... 98 Blazer

[munck]

No noises or anything. The orange lights on the switch are non existant. The switch seems dead except for the normal illumination of the diffferent positions.

[BlazerLT]

Check for vacuum leaks, check the vacuum actuator and the transfer case encoder motor.

[Turbocpe]

I would not worry or waste time with checking for vacuum leaks or the vacuum actuator, as the book does not point to that direction at all. That would not prevent any of the lights from coming on, nor would it prevent the system from failing the function test (which is what is happening since none of the lights blink when the key is first turned to On).

The book suggests there may be an open between the transfer case motor and the transfer case module. It states to check the Red/White wire between the transfer case motor and the transfer case module for continuity. I would also check the Brown/White wire from the transfer case module to the transfer case motor as well for continuity on that circuit. The book is unclear as to exactly which circuit above is the one to test.

If that checks out fine, then you need to attempt to retrieve any diagnostic codes from the transfer case module. In order to do so:

1. Make sure the ignition switch is OFF
2. Under the driver's side dash, you will see a black connector pointing towards the driver seat, down low. In small print, located Pin 13. It will be on the bottom row.
3. Use a wire from Pin 13 to a good ground source.
4. Turn the Ignition key to ON

What do the 4x4 lights do? If the lights blink one time and stop, there is no trouble codes stored.

If there is only 1 stored trouble codes, the code will repeatedly blink every 3 seconds. Count the number of blinks before the 3 second delay to determine the code.

If more than 1 code is stored, the first code will blink, then there will be a 3 second delay, then the next code will blink.

Once you have the codes, turn the ignition switch OFF and unhook the wire and report back here.

[BlazerLT]

Also, the light will not illuminate if the transfer case doesn't switch properly which again could be caused by a vacuum module or the encoder motor.

Let's not take anything out quite so prematurely.

[Turbocpe]

I'm going by the GM service book, which is a good source.

The vacuum stuff would not normally prevent the lights from coming and blinking 1 time when the Ignition key is first turned on. It is failing the diagnostic test, which is more likely to be an electrical related issue.

However, anything could be possible. Not everything has a solid explanation. So it is possible.

[BlazerLT]

True, light a corroded or burnt wire.

[munck]

Thanks for all the help, after checking to make sure both circuits from the module to the transfer case motor were not open I got more confused because I had no problems there. I then went to all data diy which I subscribe to and after spending a lot of time following the wiring diagrams I found that the interior fuse #8 for the courtesy lamps also powers the switch. That was the problem, something so simple. So actually there are 3 fuses in the interior fuse panel to look at, #5, #15 and #8.

[Turbocpe]

Good to hear that it was a simple switch issue.

I didn't recall seeing mention of this fuse in the GM book under the section I was looking at (section for no LEDs on any position). I'll have to check the book to see if I missed Fuse #8, as my Blazer is a '98 as well.

[BlazerLT]

Originally Posted by munck

Thanks for all the help, after checking to make sure both circuits from the module to the transfer case motor were not open I got more confused because I had no problems there. I then went to all data diy which I subscribe to and after spending a lot of time following the wiring diagrams I found that the interior fuse #8 for the courtesy lamps also powers the switch. That was the problem, something so simple. So actually there are 3 fuses in the interior fuse panel to look at, #5, #15 and #8.

Nice , I will remember this for future problem solving.