2000 Jimmy 4x4 Problem

Hi all,

I have done some troubleshooting to try and get my 4x4 to engage. I have replaced the actuator, solenoid vacuum switch on the firewall and the 4x4 indicator switch by the front axle.
I have a good vacuum to the actuator; the cable is not binding although the actuator will only compress about 2/3 closed. The Auto, 4HI and 4 Low lights blink continuously when pressed, I can hear the TCCM clicking, the transfer case switches when 4 Low is selected, but the lights still flash. No trouble lights on dash.

I removed the battery and tried assisting the actuator but was unable to get the front axle to engage. I jacked up the passenger front wheel, pressed the 4 HI button while slightly moving the front wheel and squeezing the actuator……… the front axle engaged and the light stayed solid. This worked in 4 Low and AutoTrac as well. When the front axle engaged, I was unable to rotate the front wheel so I am assuming the axle locked as it should.
So what the heck is going on? Could there be a problem in the front diff, I’m hoping someone can provide some direction as I believe I’ve eliminated all other potential problems as far as TCCM, bad vacuum, switches etc. It seems like everything will work fine if I can figure out how to get the coupler to engage….. or why it will not engage!! Thanks for your help.

Hi all,

I have done some troubleshooting to try and get my 4x4 to engage. I have replaced the actuator, solenoid vacuum switch on the firewall and the 4x4 indicator switch by the front axle.
I have a good vacuum to the actuator; the cable is not binding although the actuator will only compress about 2/3 closed. The Auto, 4HI and 4 Low lights blink continuously when pressed, I can hear the TCCM clicking, the transfer case switches when 4 Low is selected, but the lights still flash. No trouble lights on dash.

I removed the battery and tried assisting the actuator but was unable to get the front axle to engage. I jacked up the passenger front wheel, pressed the 4 HI button while slightly moving the front wheel and squeezing the actuator……… the front axle engaged and the light stayed solid. This worked in 4 Low and AutoTrac as well. When the front axle engaged, I was unable to rotate the front wheel so I am assuming the axle locked as it should.
So what the heck is going on? Could there be a problem in the front diff, I’m hoping someone can provide some direction as I believe I’ve eliminated all other potential problems as far as TCCM, bad vacuum, switches etc. It seems like everything will work fine if I can figure out how to get the coupler to engage….. or why it will not engage!! Thanks for your help.

If the cabel mves good and only needs a hand assist to get it in you are losing vacuum someplace.

Chek for full enginge vacuum to it and solenoid and diaphram not leaking or putting full vacuum to it.
Good luck and let us know what you find.

Thanks for your help MT, I'll keep looking for a vacuum leak. The front axle "will not" engage with a hand assist to the actuator if I do not jack up the front passenger wheel and lightly rock it? I've tried manually squeezing the actuator with all 4 wheels on the ground and no go, only when the wheel is raised and slowly rocked?

Thanks for your help MT, I'll keep looking for a vacuum leak. The front axle "will not" engage with a hand assist to the actuator if I do not jack up the front passenger wheel and lightly rock it? I've tried manually squeezing the actuator with all 4 wheels on the ground and no go, only when the wheel is raised and slowly rocked?

That is normal operation.

The axel shift gears inside have to spline up before it will lock in.
If you hit 4W and let it roll back or forward a little and it goes in 4W and axel locks up and light quits flashing all is ok.
Good Luck

Thanks MT.... I'm going to put a vacuum guage on the actuator inlet hose. Do you happen to know how many inches of vacuum I should read on the guage to get a proper pull? Thanks.

Thanks MT.... I'm going to put a vacuum guage on the actuator inlet hose. Do you happen to know how many inches of vacuum I should read on the guage to get a proper pull? Thanks.

Same as Full engine vacuum around 18-20 in hg

I'm stumpped? I have 19 in hg to the newly replaced actuator, the cable was replaced 6 months ago and I can't get the front axle to couple without assisting the actuator by adding a little bit of hand pressure. When I press on the actuator, it only travels about another 1/8 -1/4 inch and then it engages and everything is fine. I'm wondering if the binding could be happening inside the front diff..... just grassping at straws now????

I'm stumpped? I have 19 in hg to the newly replaced actuator, the cable was replaced 6 months ago and I can't get the front axle to couple without assisting the actuator by adding a little bit of hand pressure. When I press on the actuator, it only travels about another 1/8 -1/4 inch and then it engages and everything is fine. I'm wondering if the binding could be happening inside the front diff..... just grassping at straws now????

http://www.automotiveforums.com/vbulletin/showthread.php?t=572914

Hey MT!!! I got 4x4 working! I rechecked the vacuum lines and found a hole in the line from the solenoid switch to the actuator. Replaced and everything is working great.

Thanks for all your help, I really appreciate the dedication you Mod's provide..... great support site. Again, thanks alot MT!

Hey MT!!! I got 4x4 working! I rechecked the vacuum lines and found a hole in the line from the solenoid switch to the actuator. Replaced and everything is working great.

Thanks for all your help, I really appreciate the dedication you Mod's provide..... great support site. Again, thanks alot MT!

You are welcome and thanks for posting back what you found and how it went.
Good find on vacuum line.
Glad you found it.
MT

I have a similar/related issue. I found a forum on Yahoo that stated this about a 2000 Blazer. Can anyone verify if it is true?

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXX
Your Blazer shouldn't have a vacuum switch.
In the passenger side kick panel there is a Transfer Case Control Module. (TCCM) You might have heard a clicking sound coming this area...

I've recently repaired two 2000 Chevy 4X4's (http://www.blazerforum.com/forum/showthread.php?t=32164#) with basically the same troubles (no 4 wheel drive).

This a known issue with these trucks (http://www.blazerforum.com/forum/showthread.php?t=32164#), problems with corrosion built up on the pins (contacts).

You can clean the contacts of both the harness and the motor and apply die-electric grease to them and you should be good to go 4 wheelin... Hope this solves your problem!!

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX


I cannot find the Transfer Case Vacuum Switch. The Actuator under the battery leads right down into the Transfer case on the passenger side. It does not go to a Vaccuum Switch as described elsewhere on this forum.

The prob I have is some times the Right front end will sound kind of like a roar when getting to about 30 mph. If I stop and put in to 4wd (http://www.blazerforum.com/forum/showthread.php?t=32164#) and back to 2wd it will stop doing that. So I think the 4wd is trying to engage partially at times.


Any help is appreciated.

I have a similar/related issue. I found a forum on Yahoo that stated this about a 2000 Blazer. Can anyone verify if it is true?

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXX
Your Blazer shouldn't have a vacuum switch.
In the passenger side kick panel there is a Transfer Case Control Module. (TCCM) You might have heard a clicking sound coming this area...

I've recently repaired two 2000 Chevy 4X4's (http://www.blazerforum.com/forum/showthread.php?t=32164#) with basically the same troubles (no 4 wheel drive).

This a known issue with these trucks (http://www.blazerforum.com/forum/showthread.php?t=32164#), problems with corrosion built up on the pins (contacts).

You can clean the contacts of both the harness and the motor and apply die-electric grease to them and you should be good to go 4 wheelin... Hope this solves your problem!!

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX


I cannot find the Transfer Case Vacuum Switch. The Actuator under the battery leads right down into the Transfer case on the passenger side. It does not go to a Vaccuum Switch as described elsewhere on this forum.

The prob I have is some times the Right front end will sound kind of like a roar when getting to about 30 mph. If I stop and put in to 4wd (http://www.blazerforum.com/forum/showthread.php?t=32164#) and back to 2wd it will stop doing that. So I think the 4wd is trying to engage partially at times.


Any help is appreciated.

forum on Yahoo :naughty::sarcasm1::lol2:

If you need help start your on New thread and give us all info and someone will try to help you.

Wow, people, the guy was only trying to help.