On my way home from work the other day, I realized that it had been awhile since I had engaged 4x4. So close to home, on a stretch of straight residential road, I hit the 4HI button to make sure everything was in good working order. Everything engaged fine and I drove it for about a quarter mile before switching back to 2HI. When I hit the 2HI button the light changed and the transfer case disengaged. However, the truck didn’t feel quite write and I suspected the front differential did not disengage. I pulled up in my driveway and without shutting off the ignition I tried to turn the front drive shaft by hand. It wouldn’t budge. I turned off the truck and tried turning it again a couple minuets later and it turned with ease. I started the truck up and again, the drive shaft wouldn’t turn. Turn it off and it turns freely again. So on and so on….
It has been like this for a few days now. If the truck is running, the front differential is engaged. Not running, disengaged. I know the transfer case is not engaged, because I don’t hear any gear/chain whine while driving and there is no drive line bind up.
For some reason, the front differential actuator is getting vacuum when it shouldn’t be. I have a revised transfer case vacuum switch (never got around to doing this recommended change) on order from gmpartsdirect.com. I don’t know if the transfer case switch is the cause but it is worth a shot and should be changed to the newer part number anyway.
Anybody have any ideas on this little problem???
Thanks,
Pete
Front diff disengagement problem
Moderator: F9K9
Front diff disengagement problem
[size=75][url=http://photobucket.com/albums/v179/retep910/S10/]2002 S10 Ext. Cab 4x4 Indigo Blue[/url]
Extang Black Max Tonneau, Rubber Bed Mat, Vent Visors, Bugflector II, SilverStar headlights, Dark Window Tint, Disabled DRL, Debadged, K&N Filter, Skid Plates, 1.25" Rear Wheel Spacers, Boise 3 aal kit, mild T-bar crank, Dueler A/T Revo[/size]
Extang Black Max Tonneau, Rubber Bed Mat, Vent Visors, Bugflector II, SilverStar headlights, Dark Window Tint, Disabled DRL, Debadged, K&N Filter, Skid Plates, 1.25" Rear Wheel Spacers, Boise 3 aal kit, mild T-bar crank, Dueler A/T Revo[/size]
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HenryJ
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Sounds like you are headed the right direction.
Let us know what you find.
Let us know what you find.
"Speed doesn't kill, suddenly becoming stationary does." - Richard Hammond
"Speed is just a matter of Money - How fast do YOU want to go?"-Mechanic from Mad Max-
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Sounds to me like your front diff cable is engaging when the engine is running, because the vacuum actuator under the battery box is receiving vacuum in 2WD for some reason. The only thing I can think of that would cause this, is the transfer case vacuum switch sending vacuum to that vacuum actuator, when it's not supposed to. This is why I replaced all of that problematic vacuum engagement mess, with a Posi-Lok cable.
Read my write-up on this here. This will eliminate your current situation from happening, as well as give you a reliable means of engaging the front diff.....when YOU want it to engage!
Read my write-up on this here. This will eliminate your current situation from happening, as well as give you a reliable means of engaging the front diff.....when YOU want it to engage!
[size=75][b][color=orange][i]~Jeremy[/i][/color][/b]
[i][b][color=blue]'00 ZR2 Blazer, 33" KM2's on PA3's, Lock Right in Iron front diff/Detroit Locker in rear, sway-bar disco's, 1-Ton P & I Arms[/color][/b][/i]
[b][color=yellow]BlaZeR pics [/color][/b][url=http://photobucket.com/albums/b240/Muslhed/Best%20Blazer%20pics/][b][color=red]HERE[/color][/b][/url][/size]
[i][b][color=blue]'00 ZR2 Blazer, 33" KM2's on PA3's, Lock Right in Iron front diff/Detroit Locker in rear, sway-bar disco's, 1-Ton P & I Arms[/color][/b][/i]
[b][color=yellow]BlaZeR pics [/color][/b][url=http://photobucket.com/albums/b240/Muslhed/Best%20Blazer%20pics/][b][color=red]HERE[/color][/b][/url][/size]
Muslhed wrote:....Sounds to me like your front diff cable is engaging when the engine is running, because the vacuum actuator under the battery box is receiving vacuum in 2WD for some reason.
This is exactly what is happening. But why???
Muslhed wrote:This is why I replaced all of that problematic vacuum engagement mess, with a Posi-Lok cable.
I am now beginning to consider this option.
Update:
While waiting for the new transfer case switch to arrive from gmpartsdirect.com, the front diff went from being engaged while the truck was running and dis-engaged when not running to being engaged at all times. Due to the previous behavior, I do not believe that there is a problem with the cable from the vacuum actuator the diff. I am convinced it is a vacuum problem of some sort.
The new transfer case switch arrived Friday and I changed it out this morning. The good news it that there was no sign of ATF contamination in the vacuum lines as the original part no. switch is known for. The bad news is that it did not fix the problem.
I am not to good at diagnosing vacuum problems. Any body have any further ideas?
Thanks,
Pete
[size=75][url=http://photobucket.com/albums/v179/retep910/S10/]2002 S10 Ext. Cab 4x4 Indigo Blue[/url]
Extang Black Max Tonneau, Rubber Bed Mat, Vent Visors, Bugflector II, SilverStar headlights, Dark Window Tint, Disabled DRL, Debadged, K&N Filter, Skid Plates, 1.25" Rear Wheel Spacers, Boise 3 aal kit, mild T-bar crank, Dueler A/T Revo[/size]
Extang Black Max Tonneau, Rubber Bed Mat, Vent Visors, Bugflector II, SilverStar headlights, Dark Window Tint, Disabled DRL, Debadged, K&N Filter, Skid Plates, 1.25" Rear Wheel Spacers, Boise 3 aal kit, mild T-bar crank, Dueler A/T Revo[/size]
So today I check and the front diff has disengaged even while the truck is running, just like it is supposed to be. Perhaps the transfer case switch did have something to do with it. I'll try engaging 4x4 again tomorrow and see what happens.
Pete
Pete
[size=75][url=http://photobucket.com/albums/v179/retep910/S10/]2002 S10 Ext. Cab 4x4 Indigo Blue[/url]
Extang Black Max Tonneau, Rubber Bed Mat, Vent Visors, Bugflector II, SilverStar headlights, Dark Window Tint, Disabled DRL, Debadged, K&N Filter, Skid Plates, 1.25" Rear Wheel Spacers, Boise 3 aal kit, mild T-bar crank, Dueler A/T Revo[/size]
Extang Black Max Tonneau, Rubber Bed Mat, Vent Visors, Bugflector II, SilverStar headlights, Dark Window Tint, Disabled DRL, Debadged, K&N Filter, Skid Plates, 1.25" Rear Wheel Spacers, Boise 3 aal kit, mild T-bar crank, Dueler A/T Revo[/size]
Update:
I tried engaging 4HI again today. It did not engage instantly like usual but did engage fine. I did notice that the gear/chain noise was a little louder while driving in 4HI than it normally is but I might have just been paying more attention this time. I did this on a straight stretch of road. When I went to disengage, it didn't disengage instantly either. In fact it didn't disengage until I turned on to the next street. I could feel the drive line binding up in the turn and then it disengaged. when I got home and checked to see if the front diff was also disengaged I was pleased to find the front drive shaft turned freely.
The old transfer case switch may have been the cause of the front diff not disengaging but now I am curious about the slow t-case disengagement experienced today. Something else to watch
Pete
I tried engaging 4HI again today. It did not engage instantly like usual but did engage fine. I did notice that the gear/chain noise was a little louder while driving in 4HI than it normally is but I might have just been paying more attention this time. I did this on a straight stretch of road. When I went to disengage, it didn't disengage instantly either. In fact it didn't disengage until I turned on to the next street. I could feel the drive line binding up in the turn and then it disengaged. when I got home and checked to see if the front diff was also disengaged I was pleased to find the front drive shaft turned freely.
The old transfer case switch may have been the cause of the front diff not disengaging but now I am curious about the slow t-case disengagement experienced today. Something else to watch
Pete
[size=75][url=http://photobucket.com/albums/v179/retep910/S10/]2002 S10 Ext. Cab 4x4 Indigo Blue[/url]
Extang Black Max Tonneau, Rubber Bed Mat, Vent Visors, Bugflector II, SilverStar headlights, Dark Window Tint, Disabled DRL, Debadged, K&N Filter, Skid Plates, 1.25" Rear Wheel Spacers, Boise 3 aal kit, mild T-bar crank, Dueler A/T Revo[/size]
Extang Black Max Tonneau, Rubber Bed Mat, Vent Visors, Bugflector II, SilverStar headlights, Dark Window Tint, Disabled DRL, Debadged, K&N Filter, Skid Plates, 1.25" Rear Wheel Spacers, Boise 3 aal kit, mild T-bar crank, Dueler A/T Revo[/size]