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4L works. 4H don't

NYCXJ

NAXJA Forum User
Location
NYC
First of all...I'm excited about being back in the action here at NAXJA...I've been around for a couple of years now under various aliases, and I'm officially back now...no really

And I didn't come back (only) to beg for help, but while I'm here:

here it is:
My 4 low works dandy and the 4 high don't work at all (stays in 2wd mode)

any thoughts?

thanks in advance....

it really is good to be back.
 
oops

man, sorry 'bout that...

let's see...
1989
6 cyl/4.0
stock transfer case (i think)

thanks, again..
 
If it's an '89 it could be either a 231 (Command-Trac) or 242 (Selec-Trac) transfer case. The 231 was the "standard," except on the top of the line models. The 231 in '89 was mated to a front axle with a vacuum operated disconnect. I haven't heard of this happening, but it's possible that somehow your vacuum switch isn't being activated in 4-Hi but is actuated in 4-Lo.

To test, if it works in 4-Lo put it in 4WD (low range), then crawl under the passenger side of the front axle and pull the vacuum lines off the axle disconnect. That will leave the axle connected. Then shift back into high range and see if the 4WD works. If so, the vacuum lines or switch are your problem.
 
Eagle said:
If it's an '89 it could be either a 231 (Command-Trac) or 242 (Selec-Trac) transfer case. The 231 was the "standard," except on the top of the line models. The 231 in '89 was mated to a front axle with a vacuum operated disconnect. I haven't heard of this happening, but it's possible that somehow your vacuum switch isn't being activated in 4-Hi but is actuated in 4-Lo.

To test, if it works in 4-Lo put it in 4WD (low range), then crawl under the passenger side of the front axle and pull the vacuum lines off the axle disconnect. That will leave the axle connected. Then shift back into high range and see if the 4WD works. If so, the vacuum lines or switch are your problem.

Eagle, when my '87 TC vacuum switch went bad it acted like this. I'm not sure whether it was a switch issue alone or just that in 4 hi the vacuum is more likely to go low and allow a leak or malfunction to show up.
 
thanks again...

guys, thanks allot for the responses...really good to be back, i'll keep ya posted on the progress...

cheers!
 
I've got a 90 laredo with a command trac tc in it that did the same thing 4L but no 4H, i hooked up the vacuum lines that come down the passenger side fender well into the vacuum motor on the passenger side front axle and fixed it
 
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