Problem w/ High Lock?

[JetEyeNite]

Has anyone experience their 4x4 going from High to Neutral all by itself? I've been experiencing this lately. First time I tought nothing of it but I've seen this 2 days in a row now..

[PARAGON]

Originally Posted by JetEyeNite

Has anyone experience their 4x4 going from High to Neutral all by itself? I've been experiencing this lately. First time I tought nothing of it but I've seen this 2 days in a row now..

That should be next to impossible.

The tranny has to be in N for it to occur and if it's not, the BCM is screwed.

[ttkresurfacing]

I thought I saw my lights do the same the other day but then I figured I must have been seeing things. Please post if you find a problem.

Tim

[JetEyeNite]

I guess I need to call my dealer
thanks for your input Paragon...

[f5fstop]

Sounds to me like a transmission shift control module. Are you moving fast when it happens?

[JetEyeNite]

No, I wasn't moving fast at all. This morning, I noticed it when I was backing out from my drive way. Also, I noticed this when I was leaving from the office parking lot yesterday afternoon.
I hope nothing major needs replacing.....

[ttkresurfacing]

Had the dealership look at mine for same problem today and they think it has something do with wiring coming from key switch. The ychanged my key switch 10 months ago and broke the retainer clip off the harness. Now if I raise the steering wheel, the truck cuts off. They said that the harness was causing the trans light also. Told me 500 to fix it.

Tim

[PARAGON]

Originally Posted by f5fstop

Sounds to me like a transmission shift control module. Are you moving fast when it happens?

I am sure the H3 and H2 are very similar but I don't follow where the transmission shift control module would be the culprit.

The transmission has to be in neutral and speed virtually zero and then you push 4HI and 4LO together for the t-case to go to Neutral.

I haven't looked it up, but it would seem that the BCM would have to recognize that the tranny is in neutral itself before it would allow for the shift to neutral in the t-case to occur.

Nite, is it just a light coming on or does it physically go into neutral.... meaning you have no more power to the wheels.

[PARAGON]

Why does the title of the thread say HI lock if you are backing out of your driveway and coming home from work?

[JetEyeNite]

Paragon,
You are correct.. The title of the thread is incorrect. It should say "Problem with 4 High" or "Problem w/ 4 High light indicator"

This was 3rd time I've seen this. The light indicator was on "N" instead of normal 4 High. So, I press the 4 High button and it blinks for a few seconds and goes into 4 High. I don't remember not having any power.

[PARAGON]

The transfer case shift control module flashes each indicator lamp after a shift has been requested and continues to flash until the transfer case shift control module can complete the shift. If the transfer case is unable to make a shift, the requested mode indicator flashes and returns to the previous mode. If the requested mode indicator flashes for 15 seconds and returns to the previous mode, this indicates the loss of a necessary input from another module. The transfer case shift control module requires a vehicle speed sensor signal (VSS), provided by the ABS module, and a PRNDL input provided by the transmission. These signals are provided to the transfer case shift control module via class 2, and if not received the transfer case will not shift.

Also, a bad ground or connection in the tcase switch can cause the light to light-up.

Check to see if it shifts in and out of 4HI lock, 4LO, Neutral and 4HI without hiccups.

[f5fstop]

Originally Posted by PARAGON

I am sure the H3 and H2 are very similar but I don't follow where the transmission shift control module would be the culprit.

The transmission has to be in neutral and speed virtually zero and then you push 4HI and 4LO together for the t-case to go to Neutral.

I haven't looked it up, but it would seem that the BCM would have to recognize that the tranny is in neutral itself before it would allow for the shift to neutral in the t-case to occur.

Nite, is it just a light coming on or does it physically go into neutral.... meaning you have no more power to the wheels.

A failed T/case controller controls the encoder motor that engages all the different 4-wheel drive systems on the vehicle. So, if there was a major failure and it did not correctly process the information from the inputs, including the BCM via the class 2 circuit, it could attempt to engage.
It could just change the indicators too without engaging or disengaging.
I'm not saying it is the problem, all I'm saying is it could be a problem, and for a fact, a well-known problem!

[Linus Gump]

Originally Posted by ttkresurfacing

Had the dealership look at mine for same problem today and they think it has something do with wiring coming from key switch. The ychanged my key switch 10 months ago and broke the retainer clip off the harness. Now if I raise the steering wheel, the truck cuts off. They said that the harness was causing the trans light also. Told me 500 to fix it.

Tim

Why should you have to pay for a damage they caused in fixing something else?

[PARAGON]

Originally Posted by f5fstop

A failed T/case controller controls the encoder motor that engages all the different 4-wheel drive systems on the vehicle. So, if there was a major failure and it did not correctly process the information from the inputs, including the BCM via the class 2 circuit, it could attempt to engage.
It could just change the indicators too without engaging or disengaging.
I'm not saying it is the problem, all I'm saying is it could be a problem, and for a fact, a well-known problem!

Sorry, you mentioned transmission controller originally when I think you meant T-case. That's where I was confused.

I'm betting he's just getting that change of indicator lights and not actual switching in the t-case itself.

[f5fstop]

Originally Posted by PARAGON

Sorry, you mentioned transmission controller originally when I think you meant T-case. That's where I was confused.

I'm betting he's just getting that change of indicator lights and not actual switching in the t-case itself.

Oops, I did (been a bad couple weeks). I also agree, it is probably the changing of the lights, since if the t/case controller did attempt to switch into 4-low while moving and not in neutral, there should be some serious noise from under the vehicle.

[JetEyeNite]

I tried to switch from 4H to 4H lock and then switched to N.
I tried to go into 4L lock and it all worked fine.
I know I didn't hit 4H lock nor 4L lock when I noticed this problem.

So, you guys are saying that I shouldn't worry about this since it is just the indicator light?

[f5fstop]

Originally Posted by JetEyeNite

I tried to switch from 4H to 4H lock and then switched to N.
I tried to go into 4L lock and it all worked fine. TRIED, or you DID go into the different modes?
I know I didn't hit 4H lock nor 4L lock when I noticed this problem.

So, you guys are saying that I shouldn't worry about this since it is just the indicator light?

No, we are saying the t/case controller might be defective or there even could be a bad connection on one of the wires at one of the connectors (T/case or light array).
What I have to agree with is if the controller did put you into 4-wheel low lock, with the vehicle moving and in gear, chances of it going in without making some loud noises is pretty slim.
Did you feel a sudden deceleration when it engaged? If not, it didn't engage. Which means for some reason the light was going On, which means there is a problem somewhere.

[JetEyeNite]

F5FStop,
Thanks for all your help.

It did go into 4Low lock when I tried.
So, I better call my dealer..

[ScottAndDebbieHughes]

Well......2 times today our 03 H2 transfer case setting indicator light went from 4W Hi to N while driving at 30 Mph with no noticeable transition. The first time we just pulled over - put the tranny in Neutral and shifter thr T-case back to 4W Hi. All seemed good. 7 minutes later....same thing. This time followed the manuals instructions for shifting out of T-Case N. Seemes to work. Keeoing fingers crossed.

[lude]

I had this exact problem with my 03 Avalanche when it first happened i never thought anything of it but then it kept doing it as i was driving it would do it and it kept getting worse and it was shifting on its own and terrible noises got it in and cost me about 1200 was the transfer case thank god they say they have the problem fixed in the newer vehicles have not had any trouble with my 07 sut