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Hi All, I have a 2000 Chevy Blazer LT, V6, Push button 4WD
The 4WD quit working recently so I did some research on the forum. I ended up back at the transfer case thinking that my issue had something to do with vacuum lines and the Transfer case vacuum switch.
What I found were two vacuum lines disconnected and I was unable to find the vacuum switch. I have attached two pictures, one for each of the vacuum lines I found. The vacuum line with the end still attached I was able to track as far as the motor area by the tranny dipstick. The other line leads to a metal line above the tranny.
I am unsure as to what to do next, I can't find the vacuum switch on the transfer case or a third vacuum line that I think should be there based on my research. Any guidance, thoughts, questions, or suggestions would be appreciated.
I'm having a similar problem, no fix yet. 2001 s10 Blazer . Also have auto 4x4 and was surprised to not find a vacuum switch on my t-case. So far have replaced the front diff actuator, encoder motor, and the in-dash switch. It will make sounds like it's trying to go into 4 and 4-low but just won't do it. LED action on the dash 4x4 switch correlates to this action too.
Can the vacuum solenoid on the firewall go bad?
I'm having a similar problem, no fix yet. 2001 s10 Blazer . Also have auto 4x4 and was surprised to not find a vacuum switch on my t-case. So far have replaced the front diff actuator, encoder motor, and the in-dash switch. It will make sounds like it's trying to go into 4 and 4-low but just won't do it. LED action on the dash 4x4 switch correlates to this action too.
Can the vacuum solenoid on the firewall go bad?
I replaced mine when I saw that it was not holding vacuum when tested with my Mity-Vac hand pump. Be sure to test correct path; i.e. try to pull a vacuum on the supply side.
I replaced mine when I saw that it was not holding vacuum when tested with my Mity-Vac hand pump. Be sure to test correct path; i.e. try to pull a vacuum on the supply side.
Thanks for the response. Were you having 4x4 issues and did the solenoid replacement fix that?
Thanks for the response. Were you having 4x4 issues and did the solenoid replacement fix that?
I was not having problem with engagement of of the front axle but instead I replaced it when I noticed it might not have been holding vacuum very well when I was diagnosing vacuum leaks in the vacuum supply lines. I went ahead and replaced it along with all of my under-hood vacuum lines. The link below is the thread I created describing the hose lengths.
Ez to check. You may shunt the hose and by-pass that solenoid.
I've bought a ride without this exact solenoid at all. I had the vacuum switch activated permanently. The result was I had a front differential engaged instead of axles turning freely. Since transfer case didn't rotate the front differential shaft it was unnoticeable. All selections 2WD/4WD/... were working fine[1]. I've started digging around when I become pretty sure there has to be a solenoid.
[1] My firmware from '00 did not pop-up any errors by blinking led, but some newer may do.
Ez to check. You may shunt the hose and by-pass that solenoid.
I've bought a ride without this exact solenoid at all. I had the vacuum switch activated permanently. The result was I had a front differential engaged instead of axles turning freely. Since transfer case didn't rotate the front differential shaft it was unnoticeable. All selections 2WD/4WD/... were working fine[1]. I've started digging around when I become pretty sure there has to be a solenoid.
[1] My firmware from '00 did not pop-up any errors by blinking led, but some newer may do.
Thanks for the info. I messed with it a little bit yesterday. I can hear a definite hissing sound around the check valve and Tee but can't identify for certain where it's coming from exactly . The lines are all a bit worse for wear, so I'm going to replace most of them. Thanks to christine's hose sizing guide that will be a lot easier!
I'm tempted to change that vacuum solenoid just because, but using your info I can easily check it. Thanks!
I replaced the vacuum actuator (solenoid)...no change. I was able to get about half the correct sizes of hoses, the other half, no dice. This has really gotten frustrating. I've been battling this for over a year now. Replacing the lines is my last resort, but finding the time, and the correct size hoses, is the hard part.
I also bought a Dorman 47150 2-way check valve to replace the inline unit. I haven't replaced it yet but am just hoping it is the correct application. It looks similar to the check valve on the vehicle, just all black and a little larger. I checked the part number on Dorman's site (AWESOME BTW!) and it shows it as fitting my vehicle.
Last edited by Puppytank; 10-04-2018 at 05:48 PM.
Reason: new data
So actually You still don't know either it's a vacuum problem or the switch? For vacuum leak I'd take off the serpentine belt (cooling fan), start the engine and spray smoke around. You might be able to see the smoke being sucked into a vacuum. Hoses are easy to replace. Takes around 2 hours maximum, including battery shelf removal to access the actuator.
As for the switch - I'd disconnect the cable and take it out. Then You may connect the vacuum on a running engine and see whether it actuates as expected or not.
It might be also a stuck cable between switch and a front diff. Or something within diff.
Divide et impera.
10-01-2018, 04:13 PM
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