4wheel drive problem

okay lets ee if anybody has an idea about this strange problem ..

92 s15 jimmy push button 4x4 .

symptoms ...all happens when in 2 wheel drive

-- hard steering when turning left
--a squeel and or whine when trans shifted from 1st to second
-- felt like torque converter shudder after lockup only
--idle would hang when coming to a stop and then drop off to normal ,also idle would rev high on restarts .


this part was a fluke - i was looking for possibly a fuse that would disengage the lock up converter ,when i found the tccm fuse - pulled it out and all of the above problems dissapeared - of course with the ability to use the 4x4 .

the hard steering ( above ) is kind of leaning me towards an engaged axle in 2wd mode ?

with the tccm fuse in - i can engage 4x4 - but in 2wd i get all of the above .

NP233 case? Check for a vac leak first under hood and then the line back to the 3 port vac switch on the transfer case. Your front driveshaft should be free or not powered in 2wd.

yes its an np233 case - i checked the vac. lines at the 3 point switch on tcase - evrything looks good there - the drive shaft doesn't rotate in 2wd. i put the fuse (tccm ) back in - 4x4 works okay - i can hear the shift motor working in/out. but with the fuse in i get that hesitation or jerkiness in 2wd right after the tc locks up - fuse out and evrything is good except i have no 4x4. i did jump pins a & j on diag. connector under the dash and both lights on the push button flash together 1 flash pause 1 flash and this repeats - im not sure if thats just a self test or a code 1 which says 1- Ram Standby power fault : Possible open connection or short in the TCCM fuse circuit.

im thinking that is just related to when i pulled the fuse ..

So, when you put the fuse in during 2wd the TC locks up and driveshaht turns now? If so then the encoder motor is stepping to lock the drivesghaft and switch the 3 port vac on so its being powered - try the fuse in dash switch disconnected and see if thats it.

funny you say that - i'm going to try what you said and disconnect the dash switch with the fuse in , its poorng rain here tonight so i'll try tommorow and post back .. reason i say thats funny is .. last night i popped the fuse back in with truck running and i swore i heard a slight click coming from the area of the tcase ..

After some research found that the dash switch actually has 8 volts sent to it and all are normally open. The TCCM monitors return from the switch and each button has a resistor that sends a diff voltage back to the TCCM and thats how it tells what mode you want. Dorman sells the dash switch and has pics online. First step that the encoder motor does from 2wd to 4HI is to move the internal fork in the transfer case that engages the front shaft and pushes the 3 port switch ball up to direct vac to the front actuator. Next step for 4LO is engage lower gear.

bingo ..... thanks for the info muddog - problem solved - replaced dash switch .... that click i thought i was hearing was for real . disconnected the switch -no noise and a soon as i reconnected it i could hear the click again ... makes me wonder if anybody has ever had the 4x4 really engage while on the highway .....ouch. much thanks muddog .