4x4 stopped engaging...im baffled

[phuz]

had a new engine installed in my car. not sure if the 4x4 was working properly before i took it to the garage, but it DID work in the past.

got it back and tried to shift into 4x4 and it didnt engage. it is a manual transfer case. it goes into 4hi fine but it does not engage the front axles. if i put it into 4lo, the gearing in the rear changes, but the front still will not engage. the tire indicator lights on the little display do not light up either. i checked the fuse box, and the 4WD fuse is fine, and there is +B across it. i took it back to the mechanic thinking they forgot to reattach something, but they didnt, and he is as baffled as i am. we checked some alldata circuit diagrams but it isnt too clear.

if anyone has any experience with this, or any thoughts, please let me know.

thanks in advance...

matt

[1991Blazer4x4]

Check your vaccum lines. I don't know what year your truck is because you didn't mention it. Just trace the vaccum linesj that go from your transfer case. In my 91 blazer there is an "actuator" underneath the battery tray. There will probaly be like 3 vaccum lines. Let us know if you get anywhere.

[phuz]

i will check it. its a 1995 LS btw.

[Fireplug]

check vacuum switch on the transfer case

[1991Blazer4x4]

Did you figure it out yet?

[phuz]

i have not yet. i plan to check it out tomorrow night when im able to get in a garage and jack it up. where exactly does this line go? a description or picture might help because i didnt see it. thanks

[phuz]

i checked it out and found that there is a vacuum line connected to the transfer case with a T-fitting right by it. not sure where the other end goes. was hard to see where the line traveled but behind the plenom i found a metal line that came up and was capped off for some reason. there was a vacuum line attached over top of it and it ran to an electronically controlled valve to the left side of the plenom. i just removed the cap so now there is control. i hope that was the right move. but i still dont have 4x4. any ideas appreciated.

matt

[BlazerLT]

Don't aimlessly uncap and change things without knowing what you are doing.

Follow the vacuum lines going from the transfer case and vacuum switch and look for a line that is not attached.

[phuz]

well, if it isn't the vacuum that is the problem, what else could suddenly stop the 4wd from engaging?
matt

[BlazerLT]

Vacuum actuator on the transfer case has failed.

Very common problem.

[phuz]

how expensive is this?

[BlazerLT]

Call the parts dealer tomorrow and ask.

[phuz]

im talking about labor and what. is this something that the tranny needs to be dropped for?

[rlith]

No, the switch is 14 bux in the HELP section of your local auto parts store. Use a 7/8th's box wrench to remove it. Now before you start doing that, check the following.

1st: Pull up your battery tray (3 13mm bolts) and look at the vac servo under there. Is it torn? (If so replace it) If you squeeze it (carefully) is it pulling on the cable? (it should if the clip is seated properly). Is the vac hose attached?

2nd Follow the vac hose from that diaphram to the vac switch on the transfer case. Check for cracks, breaks, et-al. (If you've had the abs recall done it will go from the diaphram to a t connected to the moduylator attached to the water bottle then down to the transfer case)

3rd follow the other vac line from the switch to the main vac system. Again no cracks or breaks should be present.

Now if all this is good, now go change the switch on the vacume case.

If this doesn't solve it it's your encoder motor.

[phuz]

couple of things before i check all this tomorrow. is it a certain switch that i must buy, or do i need to remove the old one and take it in with me?

if the vac servo is cracked, where do i get one? again, if at a parts store, is it something i should take in?

and thank u for the help. all of u!!!