idosubaru Posted March 27, 2014 Share Posted March 27, 2014 I replaced the solenoid, same exact symptoms. The 4WD locking mechanism is staying locked. 1988 XT6. All vacuum lines, wiring, and buttons look fine. As mentioned, i replaced the solenoid and no change in symptoms. Could that large circular doohickey on the side of the transmission be to blame? What is that thing anyway? Quote Link to comment Share on other sites More sharing options...
ruparts Posted March 27, 2014 Share Posted March 27, 2014 (edited) hi, i would try to manually disengage it, try to see if the linkage is just stuck or binding. i had a manual select 2wd /4wd just needed to move the lever on the trans and it worked fine after that, just stuck. the inner cable from the diaphram might be stuck and the vacuum just can't move it, if you can get to the lever or whatever on the trans try and move it there, might have to disconnect the linkage to try it. automatics have a circular thing on the shifter linkage it's the selector switch and i don't think that would be affecting the 4wd lock. Edited March 27, 2014 by ruparts Quote Link to comment Share on other sites More sharing options...
idosubaru Posted March 27, 2014 Author Share Posted March 27, 2014 (edited) oh right, it's a manual transmission. copy, i'll disconnect it, see if i see anything obvious while i do. at least winter is on the way out so no big deal. Edited March 27, 2014 by grossgary Quote Link to comment Share on other sites More sharing options...
MilesFox Posted March 27, 2014 Share Posted March 27, 2014 the button on the shifter is a double pole-double throw. the solenoids should be one on and one off, alternately withthe button. If there is a disfunction of the button, or one of the solenoids, you can simply reverse the vacuum lines to get the 4wd diaphragm to engage or disengage each time if the solenoid or switch is stuck in one position. This works presuming the diaphragm is working. If this does not work, suspect the diaphragm itself. You should be able to manually manipulate the cable on the diaphragm. If it seem s stuck, try rolling the car forward or backward a little, wheels straight, or jack up one side of the car to releive any bind in the 4wd Quote Link to comment Share on other sites More sharing options...
idosubaru Posted March 27, 2014 Author Share Posted March 27, 2014 If there is a disfunction of the button, or one of the solenoids, you can simply reverse the vacuum lines to get the 4wd diaphragm to engage or disengage each time if the solenoid or switch is stuck in one position. This works presuming the diaphragm is working. If this does not work, suspect the diaphragm itself.d ah ha thanks Miles - i did exactly that - swapped the two vacuum lines on the solenoids and there was no change. so the diaphragm is that big circular thing on the transmission - it likely needs replaced? are those easily replaced in the vehicle? i hope so. Quote Link to comment Share on other sites More sharing options...
MilesFox Posted March 27, 2014 Share Posted March 27, 2014 you can get to it. the diaphragm is mounted to a bracket that has 3 bolts or so bolting it to the trans case. the other end is a clevis pin with a cotter pin holding it to the actiuator on the back of the trans. I believe moving the cable forward is 4wd and backward is FWD it is unlikely the diaphragm is failed, unless the metal part is rusted through or the whole thing is soaked in oil for a long time. check your vacuum source. IF all of your heat selectors only blow out of the dash vents, there is your problem. check for the small hose going from the vacuum canister to the intake. Quote Link to comment Share on other sites More sharing options...
scoobiedubie Posted March 27, 2014 Share Posted March 27, 2014 I just replaced my 4wd vacuum switches because I couldn't get it into 4wd. $13 for a used part and the GL/Loyales may use the identical part. It is at the opposite end of the vacuum lines coming off of the diaphragm. Quote Link to comment Share on other sites More sharing options...
Gloyale Posted March 27, 2014 Share Posted March 27, 2014 I just replaced my 4wd vacuum switches because I couldn't get it into 4wd. $13 for a used part and the GL/Loyales may use the identical part. It is at the opposite end of the vacuum lines coming off of the diaphragm. He said he did that in the first sentence. He called them "the solenoid" but both are true, they're actually set of solenoid switches. He also said he's reversed them to no affect. Gary.....What I would do is first check for 12v alternately to each solenoid as the button is switched. Just verify voltage....if neither has voltage both will be closed so no 4wd movement....OK? No power....test at switch and so on. Got power? If yes then next, to test the diaphragm find the 2 vac lines leading down to the diaphragm from the solenoids.........take the Vac supply line while the engine is running (make sure it got vac) and alternately apply vac to each of the diaphragm lines......IIRC the line on the cable side is the "pusher" side that moves the cable into 4wd. If you get no response, try pulling the cotter pin from the cable and testing the actual lever on the lower pass. side of trans rear. If the lever moves but still the cable will not then the diaphragm is bad. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted March 27, 2014 Author Share Posted March 27, 2014 Gloyale - Thank you much, makes perfect sense, that system wasn't clear to me. ***Question: Is it like a momentary switch - it only needs vacuum to move/switch, but not stay in position? Or does it need "constant" vacuum to stay in one, or both, positions? I'm almost positive I applied vacuum to the diaphragm but I was unclear how it worked so who knows if i did it right or tried both. Quote Link to comment Share on other sites More sharing options...
wagonist Posted March 27, 2014 Share Posted March 27, 2014 Can you manually move the cable? I've seen other queries of the same problem on here where it ended up that the cable between the diaphragm & selector was seized inside the sleeve. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted March 28, 2014 Author Share Posted March 28, 2014 Can you manually move the cable? I've seen other queries of the same problem on here where it ended up that the cable between the diaphragm & selector was seized inside the sleeve. i unbolted the bracket on the side of the transmission and could not move the cable. so either: 1. that bracket alone isn't enough slack to move it 2. the lever is under load and can't move by hand (binding?) 3. it's seized like you said. i did this 10 years ago and i'm almost positive i simply unbolted that side bracket and moved the lever. at that time i attached a rod to it and passed it into the cabin so i could just shift it by hand. LOL i'll have to try jack the car up and seeing if i can unload the gears/diff and if that might help, i didn't see any threads or info regarding that cable seizing in the sleeve, but i get what you're saying since i've taken apart some speedo cables that get corroded/rusty inside the sleeve. this is a west coast vehicle with no rust...but who knows. Quote Link to comment Share on other sites More sharing options...
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