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'99 Blazer; 4x4 Issue

 
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John

External


Since: Aug 17, 2007
Posts: 2



(Msg. 1) Posted: Fri Aug 17, 2007 4:55 pm
Post subject: '99 Blazer; 4x4 Issue
Archived from groups: alt>autos>4x4>chevy-trucks (more info?)

I have a '99 Blazer with the 4-Button AutoTrac system. Its 4x4 has
been out for some time. I haven't really made it a priority because of
the mild winters we have had in Ohio lately. In any case, I can shift
it into 4HI, but there is where it gets stuck. I can hit the 2HI and
it will blink, and then go back to 4HI. Same for 4LO. I can switch it
to AUTO and it will stay there. To drive the truck, I found out that I
can press the 2HI and 4HI buttons repeatedly and the system will
basically turn off and there will be no lights on the selector switch.
I'm assuming the transfer case is still in 4HI, but the front
differential is disengaged. After a few days it goes back to 2HI and
I'm not sure how or why.

I know from these systems it can be the switch on the dash, the TCCM,
the encoder motor, or the vacuum actuator on the front differential.
The lights on the switch are working fine, so I don't think it is the
cold solder issue that is so common. The TCCM makes a definite click
when the buttons are pushed, but I haven't ruled it out yet. I tested
the vacuum actuator and it seems to engage / disengaged properly. So
everything pointed me to the encoder motor. I took it down, still
hooked up to the wire harnesses and push the selector buttons. It may
a lot of noise, but the key that fits to the transfer case didn't move
at all. I figured it was bad and got a replacement at the junkyard. It
does the same thing so now I'm back to square one.

I do get a Service 4x4 light, but I can't pull the code because it is
the AWD system and it requires the GM Tech2 scan tool. So I can't
ground any pins to read the code. I have tried clearing the codes, etc
and no luck. If needed, I can take it to the dealer to get the codes
read, but I'm trying to avoid their $ervice charge.

I figured it could a number of different issues:

1. The encoder motor from the junkyard was bad as well. (It made the
same noise, didn't move etc)
2. TCCM is bad.
3. Front Differential is actually not disengaging properly.

What do you guys think?

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Steve W.

External


Since: Nov 24, 2006
Posts: 93



(Msg. 2) Posted: Fri Aug 17, 2007 8:36 pm
Post subject: Re: '99 Blazer; 4x4 Issue [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)

John wrote:
> I have a '99 Blazer with the 4-Button AutoTrac system. Its 4x4 has
> been out for some time. I haven't really made it a priority because of
> the mild winters we have had in Ohio lately. In any case, I can shift
> it into 4HI, but there is where it gets stuck. I can hit the 2HI and
> it will blink, and then go back to 4HI. Same for 4LO. I can switch it
> to AUTO and it will stay there. To drive the truck, I found out that I
> can press the 2HI and 4HI buttons repeatedly and the system will
> basically turn off and there will be no lights on the selector switch.
> I'm assuming the transfer case is still in 4HI, but the front
> differential is disengaged. After a few days it goes back to 2HI and
> I'm not sure how or why.
>
> I know from these systems it can be the switch on the dash, the TCCM,
> the encoder motor, or the vacuum actuator on the front differential.
> The lights on the switch are working fine, so I don't think it is the
> cold solder issue that is so common. The TCCM makes a definite click
> when the buttons are pushed, but I haven't ruled it out yet. I tested
> the vacuum actuator and it seems to engage / disengaged properly. So
> everything pointed me to the encoder motor. I took it down, still
> hooked up to the wire harnesses and push the selector buttons. It may
> a lot of noise, but the key that fits to the transfer case didn't move
> at all. I figured it was bad and got a replacement at the junkyard. It
> does the same thing so now I'm back to square one.
>
> I do get a Service 4x4 light, but I can't pull the code because it is
> the AWD system and it requires the GM Tech2 scan tool. So I can't
> ground any pins to read the code. I have tried clearing the codes, etc
> and no luck. If needed, I can take it to the dealer to get the codes
> read, but I'm trying to avoid their $ervice charge.
>
> I figured it could a number of different issues:
>
> 1. The encoder motor from the junkyard was bad as well. (It made the
> same noise, didn't move etc)
> 2. TCCM is bad.
> 3. Front Differential is actually not disengaging properly.
>
> What do you guys think?
>

Take it in and find out what the codes are. Otherwise plan on spending a
LOT of money tossing parts at it.
Oh and you can add that it could be a bad harness connection, bad front
clutch pack, or bad switch to your list. Could even be inside the
transfer case as well.

--
Steve W.
Near Cooperstown, New York

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A|ice

External


Since: Dec 19, 2006
Posts: 5



(Msg. 3) Posted: Thu Sep 06, 2007 11:27 pm
Post subject: Re: '99 Blazer; 4x4 Issue [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)

I have a 1998 S10Blazer and had the same problem with it. It only seemed to
happen in the winter though.
I took it to a transmission shop, this was a few years ago and I can't
remember what piece they said had worn off inside 'cause it was made of
plastic.

Anyway...winter before last, it had done the same thing to me but got stuck
in 4LO and couldn't get it out until I messed with the buttons.
Then, I couldn't get it back into 4HI.

I was leaving a parking lot one afternoon and kinda got on it to beat
traffic when the back wheel must've started to spin a little.
It put itself into 4HI itself. It worked okay after that until last winter
and started the whole thing over again.



"Steve W." wrote in message
> John wrote:
>> I have a '99 Blazer with the 4-Button AutoTrac system. Its 4x4 has
>> been out for some time. I haven't really made it a priority because of
>> the mild winters we have had in Ohio lately. In any case, I can shift
>> it into 4HI, but there is where it gets stuck. I can hit the 2HI and
>> it will blink, and then go back to 4HI. Same for 4LO. I can switch it
>> to AUTO and it will stay there. To drive the truck, I found out that I
>> can press the 2HI and 4HI buttons repeatedly and the system will
>> basically turn off and there will be no lights on the selector switch.
>> I'm assuming the transfer case is still in 4HI, but the front
>> differential is disengaged. After a few days it goes back to 2HI and
>> I'm not sure how or why.
>>
>> I know from these systems it can be the switch on the dash, the TCCM,
>> the encoder motor, or the vacuum actuator on the front differential.
>> The lights on the switch are working fine, so I don't think it is the
>> cold solder issue that is so common. The TCCM makes a definite click
>> when the buttons are pushed, but I haven't ruled it out yet. I tested
>> the vacuum actuator and it seems to engage / disengaged properly. So
>> everything pointed me to the encoder motor. I took it down, still
>> hooked up to the wire harnesses and push the selector buttons. It may
>> a lot of noise, but the key that fits to the transfer case didn't move
>> at all. I figured it was bad and got a replacement at the junkyard. It
>> does the same thing so now I'm back to square one.
>>
>> I do get a Service 4x4 light, but I can't pull the code because it is
>> the AWD system and it requires the GM Tech2 scan tool. So I can't
>> ground any pins to read the code. I have tried clearing the codes, etc
>> and no luck. If needed, I can take it to the dealer to get the codes
>> read, but I'm trying to avoid their $ervice charge.
>>
>> I figured it could a number of different issues:
>>
>> 1. The encoder motor from the junkyard was bad as well. (It made the
>> same noise, didn't move etc)
>> 2. TCCM is bad.
>> 3. Front Differential is actually not disengaging properly.
>>
>> What do you guys think?
>>
>
> Take it in and find out what the codes are. Otherwise plan on spending a
> LOT of money tossing parts at it.
> Oh and you can add that it could be a bad harness connection, bad front
> clutch pack, or bad switch to your list. Could even be inside the transfer
> case as well.
>
> --
> Steve W.
> Near Cooperstown, New York
 >> Stay informed about: '99 Blazer; 4x4 Issue 
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A|ice

External


Since: Dec 19, 2006
Posts: 5



(Msg. 4) Posted: Thu Sep 06, 2007 11:27 pm
Post subject: Re: '99 Blazer; 4x4 Issue [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)

I have a 1998 S10Blazer and had the same problem with it. It only seemed to
happen in the winter though.
I took it to a transmission shop, this was a few years ago and I can't
remember what piece they said had worn off inside 'cause it was made of
plastic.

Anyway...winter before last, it had done the same thing to me but got stuck
in 4LO and couldn't get it out until I messed with the buttons.
Then, I couldn't get it back into 4HI.

I was leaving a parking lot one afternoon and kinda got on it to beat
traffic when the back wheel must've started to spin a little.
It put itself into 4HI itself. It worked okay after that until last winter
and started the whole thing over again.



"Steve W." wrote in message
> John wrote:
>> I have a '99 Blazer with the 4-Button AutoTrac system. Its 4x4 has
>> been out for some time. I haven't really made it a priority because of
>> the mild winters we have had in Ohio lately. In any case, I can shift
>> it into 4HI, but there is where it gets stuck. I can hit the 2HI and
>> it will blink, and then go back to 4HI. Same for 4LO. I can switch it
>> to AUTO and it will stay there. To drive the truck, I found out that I
>> can press the 2HI and 4HI buttons repeatedly and the system will
>> basically turn off and there will be no lights on the selector switch.
>> I'm assuming the transfer case is still in 4HI, but the front
>> differential is disengaged. After a few days it goes back to 2HI and
>> I'm not sure how or why.
>>
>> I know from these systems it can be the switch on the dash, the TCCM,
>> the encoder motor, or the vacuum actuator on the front differential.
>> The lights on the switch are working fine, so I don't think it is the
>> cold solder issue that is so common. The TCCM makes a definite click
>> when the buttons are pushed, but I haven't ruled it out yet. I tested
>> the vacuum actuator and it seems to engage / disengaged properly. So
>> everything pointed me to the encoder motor. I took it down, still
>> hooked up to the wire harnesses and push the selector buttons. It may
>> a lot of noise, but the key that fits to the transfer case didn't move
>> at all. I figured it was bad and got a replacement at the junkyard. It
>> does the same thing so now I'm back to square one.
>>
>> I do get a Service 4x4 light, but I can't pull the code because it is
>> the AWD system and it requires the GM Tech2 scan tool. So I can't
>> ground any pins to read the code. I have tried clearing the codes, etc
>> and no luck. If needed, I can take it to the dealer to get the codes
>> read, but I'm trying to avoid their $ervice charge.
>>
>> I figured it could a number of different issues:
>>
>> 1. The encoder motor from the junkyard was bad as well. (It made the
>> same noise, didn't move etc)
>> 2. TCCM is bad.
>> 3. Front Differential is actually not disengaging properly.
>>
>> What do you guys think?
>>
>
> Take it in and find out what the codes are. Otherwise plan on spending a
> LOT of money tossing parts at it.
> Oh and you can add that it could be a bad harness connection, bad front
> clutch pack, or bad switch to your list. Could even be inside the transfer
> case as well.
>
> --
> Steve W.
> Near Cooperstown, New York
 >> Stay informed about: '99 Blazer; 4x4 Issue 
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