Goinghuntin Posted May 18, 2010 Report Share Posted May 18, 2010 I've got a '95 Jimmy and last week I lost the four-wheel drive in it. SOOOO I replaced the vacuum switch on top of the transfer case, that was stuck in the closed position. Didn't fix it. Found a few leaks in the vacuum lines, that still didn't fix it. Found out the line on the diaphragm axle actuator was slipping off. Put that back on, still doesn't work :jaw: Now what Shaun? I know my Dad's '99 Blazer has another vacuum switch on the firewall but I can't find one on my Jimmy. What is there left to do besides driving the truck into a pond and collecting insurance? Nathan Quote Link to comment Share on other sites More sharing options...
redkneck Posted May 18, 2010 Report Share Posted May 18, 2010 What is there left to do besides driving the truck into a pond and collecting insurance? Nathan Dude, you're still carrying full coverage on a 95 Jimmy? I'm wondering if the switch you put on may be bad. We had the same issue on pop's 95 chevy and a new switch did the trick. Do you have any vacuum pressure at all on the hose? Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted May 18, 2010 Report Share Posted May 18, 2010 Front axle. There is an electronic switch for the front axle that engages it, they used a plug that could be pulled loose. Check to make sure that wire is connected. Quote Link to comment Share on other sites More sharing options...
Goinghuntin Posted May 18, 2010 Author Report Share Posted May 18, 2010 Dude, you're still carrying full coverage on a 95 Jimmy? No but a 30 second phone call says I do I'm wondering if the switch you put on may be bad. We had the same issue on pop's 95 chevy and a new switch did the trick. Do you have any vacuum pressure at all on the hose? It may be. It seems as though there is vacuum coming to the switch, but not out of it. And I gave no clue what the third line coming off the switch is for. It leads up into the engine compartment but is capped off, and by the looks of it, has been for years :bang: And wtnhunt, I tested the front axle switch, and I've got a good ohm rating coming through it. Nathan Quote Link to comment Share on other sites More sharing options...
MUDRUNNER Posted May 18, 2010 Report Share Posted May 18, 2010 Front axle. There is an electronic switch for the front axle that engages it, they used a plug that could be pulled loose. Check to make sure that wire is connected. Faulty actuator in the front diff. would've been my best guess. I believe G.M.'s around that year were pretty notoriuos for the actuators going out. Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted May 18, 2010 Report Share Posted May 18, 2010 And wtnhunt, I tested the front axle switch, and I've got a good ohm rating coming through it. Nathan Faulty actuator in the front diff. would've been my best guess. I believe G.M.'s around that year were pretty notoriuos for the actuators going out. Bad design imho how that plug connnected to the axle, pretty sure the plug on my 92 got knocked loose by some brush when I was driving through a field to recover a deer the very first time I ever had to put the truck in 4wd, either that or it was loose when I bought the truck. Any way you look at it, I would make sure that plug going to the axle is connected and make sure especially if you have had the axles under water that the plug is clean. Seems like I ended up using heavy duty tie wraps and tied the wire down tight to the axle just before where it plugged in to secure it. My truck got stuck on wet grass going slightly uphill when that wire/plug had come loose, after I figured out the problem and made sure it would stay put I never had any other issues with it engaging the front axle. Quote Link to comment Share on other sites More sharing options...
Goinghuntin Posted May 18, 2010 Author Report Share Posted May 18, 2010 Bad design imho how that plug connnected to the axle, pretty sure the plug on my 92 got knocked loose by some brush when I was driving through a field to recover a deer the very first time I ever had to put the truck in 4wd, either that or it was loose when I bought the truck. Do you mean the cable running from the vacuum diaphragm down into the axle or the two prong switch that mounts on the axle? Nathan Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted May 18, 2010 Report Share Posted May 18, 2010 Do you mean the cable running from the vacuum diaphragm down into the axle or the two prong switch that mounts on the axle? Nathan I was talking about the 2 wire plug/connector that goes to the axle. Quote Link to comment Share on other sites More sharing options...
Goinghuntin Posted May 18, 2010 Author Report Share Posted May 18, 2010 I was talking about the 2 wire plug/connector that goes to the axle. Ok. I checked it and it appears to be working fine. I have had a problem with that before though. Mud got in the terminals and the truck wouldn't switch into 4hi or 4lo until I cleaned all the mud out. This time it seems to be a vacuum-related problem though. I've been trying to find both a vacuum and wiring schematic for the 4wd but so far, nothing. Nathan Quote Link to comment Share on other sites More sharing options...
redkneck Posted May 18, 2010 Report Share Posted May 18, 2010 I bet Shaun can help you out with that. Don't know what to tell you, sounds like you covered the basics of it. Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted May 18, 2010 Report Share Posted May 18, 2010 I've been trying to find both a vacuum and wiring schematic for the 4wd but so far, nothing. Nathan Don't know about now, but years ago Haynes or Chiltons manuals used to have pretty good diagrams for all that. Quote Link to comment Share on other sites More sharing options...
Goinghuntin Posted May 18, 2010 Author Report Share Posted May 18, 2010 Don't know about now, but years ago Haynes or Chiltons manuals used to have pretty good diagrams for all that. My Dad's got a haynes manual and I have the chilton's manual. Neither cover the 4wd schematics Nathan Quote Link to comment Share on other sites More sharing options...
redkneck Posted May 18, 2010 Report Share Posted May 18, 2010 Did you check the actuator on the transfer case? There's also a fuse that goes to it that can blow sometimes. Quote Link to comment Share on other sites More sharing options...
redkneck Posted May 18, 2010 Report Share Posted May 18, 2010 Was looking around in another forum I use for truck issues (slow week, boss out of town). Check this out. http://www.gm-trucks.com/forums/index.php?showtopic=49202&hl=actuator Quote Link to comment Share on other sites More sharing options...
redkneck Posted May 18, 2010 Report Share Posted May 18, 2010 Another: http://www.gm-trucks.com/forums/index.php?showtopic=36254&hl=actuator Quote Link to comment Share on other sites More sharing options...
Goinghuntin Posted May 19, 2010 Author Report Share Posted May 19, 2010 Checked out two of the lines coming off the transfer case switch, the main line coming off the intake and the line running up to the actuator on the fender. Both lines are good, so the third line, the vent line I think, must be bad somewhere or clogged. Not sure if a clogged line would keep it from shifting into 4wd Nathan Quote Link to comment Share on other sites More sharing options...
Goinghuntin Posted May 20, 2010 Author Report Share Posted May 20, 2010 After a couple more tests and visuals today I found out that the front axle is engaging, finally. However I'm still not getting 4WD. I've heard that if the vacuum switch on the transfer case goes bad (which it did) it can throw out the front diff. Is that true Shaun? Nathan Quote Link to comment Share on other sites More sharing options...
Shaun_300 Posted May 20, 2010 Report Share Posted May 20, 2010 I can't see it taking out the front diff. It sounds like the problem may be inside the transfer case itself, sounds like you've checked everything else. Quote Link to comment Share on other sites More sharing options...
Goinghuntin Posted May 20, 2010 Author Report Share Posted May 20, 2010 sounds like you've checked everything else. Yeah, about fifteen times :jaw: Nathan Quote Link to comment Share on other sites More sharing options...
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