I agree! Hate push button 4x4. I also have a clean stock Blazer ZR2 & my rubber on the actuator cracks or breaks every 4-6 months. It’s below my battery & all is stock. It’s clear from any objects, etc. but still goes bad often. I bought mine at O’Riellys & came with a lifetime warranty. I’m on my 5th actuator now in the past 1 1/2yrs. I just keep taking it back & getting a free replacement
THANK YOU! Found the same rubber seal ripped on mine. I'm tight on money and couldn't afford to take it somewhere. Ill be able to take an extra beach trip this summer!
I had an '84 pickup. Put 200k miles on it with zero drivetrain issues. Not even a u-joint. And I even auto-crossed it several times. I ran it in 4x4 low on dry pavement to take advantage of gearing and traction that were better suited to the course.
@amazingaustin16 yes... the lights in the dash indicated 4wd HI or 4wd low. the front drive shaft was spinning but the front differential was not engaged because the rubber vacuum actuator had a rip in the diaphragm... get a friend to operate the 4wd buttons in the cab while you are watching the actuator... you will need to remove the battery and battery tray and use jumper cables to power the truck 4 this test.
I have disconnected the vacuum actuator tube and capped it, and haven't had the noise since, I will eventually get the vacuum switch replaced. I think that the vacuum leaks/builds up over time while driving and the vacuum builds up in the actuator eventually causing the preengagement grinding sound, but I do hear like a gear humming sound,not grinding now, thanks for telling me about the front differential fluid, I didn't even know there was fluid there, I will have to check that out.
This video was relevant for me, and I'm replacing the cable on my 84 S10 Blazer.. The only difference was that my 4WD actuator is mounted on the top of the inner fender well instead of under the battery. Very useful though, i would have had no idea about the side of the cable that connects to the axle.
The spring is inside the vacuum actuator and it pulls on the cable as it should. I disconnected the vacuum tube, and haven't heard the grinding since. Thanks for your help.
Manual states you can put it in 4 HI while moving at any speed, but must be in Neutral to engage 4 LO. My S10 won't let you go to 4 LO when your in gear.
i have a 95 4x4 blazer .i have checked the accuator it is in good shape the cable seems to be releasing like it should .but on ice cant get it to lock in either 4 hi or 4lo .no sure where all 3 hoses go to from th vacuum switch .took the switch out and tested it had good voltage.
@amazingaustin16 you got it. make sure you don't weld the + cable to the fender of the truck... tie a shirt around the jumper cable clamp or put a piece of cardboard on top of the fender...
i think there is a spring that by default (when not in 4wd) pushes the gears apart in the front end to keep them disengaged. when you put it in 4wd, the vacuum actuator pushes a gear (that slides) against the spring and then the 2 gears engage. It sounds to me like your spring is tired/worn and over the course of a day, the gear that slides is moving towards the other gear.
i know there was a recall on the switch in the front differential that (I assume) detected if it was locked in or out. Maybe this is bad on your truck. Also, make sure you figure out if it is your transfer case and/or your front diff locked in... this may help you diag the issue. if front diff is locked in, the cable to your vacuum solenoid could be chaffed and rusty. if it is your transfer case, you may have a bad transfer case motor... can you hear the motor spinning?
I know this is a old video but how about this one, I need help. My truck is stuck in 4 low. When I push 2 hi or 4 high I hear clicks and the lights blink then shut off. I checked the lines and made sure everything was hooked up right, fixed any leaks etc etc. I have vacuum to the actuator. Its closed tight but I can't seem to get it out of 4 low. I don't even care about having 4 wheel right now. I just need it in 2 wheel so I can drive the thing on the highway and not mess anything up.... I replaced the switch by the transfer case, added dif oil, checked the cable for a break and nothing. I just don't understand why even when no vacuum is hooked to the actuator why will it not release that cable and manually put it in 2 wheel mode... I'm thinking about buying another actuator but I'm tired of wasted money. The actuator looks good like I said it does have vacuum and closes and when I release the vacuum it does expand..... Someone help. I looked at forms and everything else but nothing has worked ...
I have had this issue with 4wd lo and sometimes 4wd hi... The trick I was told was to get it onto a slope and roll it downhill in Neutral. then press the 2wd button and it should shift out. It did for me. I occasionally get all sorts of crazy torque on the rear wheels. The rear wheel spins like it is off the ground. I looked at the piece mentioned in this video and in anouther vid. It doens't move very freely and the cable spring is rusted to hell.
this process is really hard on the gears and electric motor in the transfer case. try to diag if the transfer case is working by putting it in 4Low. if you drive in 2wd but really slow, the transfer case is working and the problem is your front axle. I had this situation once and it was the front axle vacuum actuator that had failed. replaced it and same problem a month later but this time the cable slipped off the actuator.
I would guess you have the gears binding on the transfer case shaft. It would be interesting to remove the motor and try to actuate the gear change yourself using a screw driver or other implement. You may find it extremely difficult to shift. Was the transfer case ever too low on fluid? If it is binding, unfortunately it would likely need to come apart and have parts or shims or something replaced to resolve the problem.
I have a 95 Jimmy and it made a horrible grinding noise unless I put it in 4wd and took it back out, finally figured out my front diff was leaking fluid, filled it up and the problem went away. Still need to change my seal but maybe thats whats wrong with yours as well.
Hi there dstorm3. It is very unfortunate but most 4wd systems really only easily go in and out of 4wd when the vehcile is slowly rolling. when i put mine in/out, I try to get it rolling about 5km/hr in neutral. with this condition, the gears in the transfer case and front end are not under stress and can easily mesh. Unfortunately when you get stuck, this gear meshing is much harder and requires you to be gently spin rear wheels while the electric motor/vacuum actuator are trying to engage.
@mrsillyman....when your actuator went bad did the dash lights still imdicate you were in.4wd? thats what mine is doing..also the front driveshaft spins in 4wd but power ist transfered to the front wheels
I know this is a long time ago, but i have new transfer case motor, new push buttons, have had the vacuum diagnosed and there is pressure, my lights on dash also show it is working along with the transmission acting according to whether im in 4Lo or 4Hi., the computer box is telling the transfer case motor to work. So it's tricky to me. I'll have to find actuator but i don't know what else to look at because everything is appearing to work when diagnosed by myself or mechanic.
My 91 Jimmy is making a grinding noise even with this vacuum actuator disconnected. Someone said the noise was from the front wheel partially engaging, and thats why I disconnected the vacuum actuator. Strange thing was I disconnected this last time when I had this problem and it worked for like 2 years without any noise, then I had the vacuum switch replaced figuring the switch was leaking vacuum into the actuator and had no problem for like 3 weeks, but now the grinding noise came back even though the actuator is disconnected. But noise goes away when I shift into 4WD? What should I do?
I really need someone to reply to this comment. I’ve replaced the vacuum switch on the transfer case. I’ve checked all the hoses. The actuator is fine. The only thing I know that’s for sure messed up are the buttons themselves but I can get those to work enough to press them. The actuator is always fully sucked and has the cable pulled at all times yet the front wheels aren’t engaged. And when I press the buttons, all I get is a clicking in the differential and a whole lot of nothing after that. What do I do?
Jack it up the front wheels off of the ground. put it in 2wd. crawl under the truck and manually spin the drive shaft between the transfer case and front diff. From memory, I think it should spin freely. Next, put it in 4wd. Now try to spin the same shaft. It should not spin freely now. This should rule out your transfer case. next, with it in 4wd, rotate one of the front wheels. the other front wheel should rotate the opposite way. if the other front wheel does not spin, your front diff is not engaging. get someone to put it in and out of 4wd while you are watching the vacuum accurator. If the actuator moves when 2->4wd and 4wd->2wd, it isn't your electronics, switches or vacuum lines and is likely your front diff.
My problem is that the 4WD drive is grinding, and seems to be trying to engage itself, could the vacuum switch be leaking vacuum to the vacuum actuator? I have a 91 GMC Jimmy with the original rubber, and that works and is not ripped, but its scarry to hear grinding to start at 50 mph. Or what could cause this grinding with the 4WD? I know its the 4WD because if I engage it and disgengage it goes away for a day. Thanks
would the vacuum be in the same place on a chevy silverado 1990 cause im having issues also with my 4 wheel it wont engage at all it's stuck in 2 wheel stick shift wont move ,so im wondering if it's the vacuum or is it that little bolt or both .any help is very apprieciated. thanks
My 01 gmc jimmy s15 series will get stuck in 4hi and wont go into any other gear besides auto 4wheel , changed transfer case motor still wont get out of 4hi i can hear the actuator motor working when i push the button on the dash and can hear the tccm clicking under the dash. have u ever encountered any problems like this before any help would be aprecciated
Hi. Sorry I don't have a diagram but recall some of the vacuum lines going to the transfer case. Trace those lines and it should be obvious where they go.
My switch will not light up, also is there some sort of relay that clicks to actuate the vacuum valve in the dash? My fuse is good. I have a 1994 Chevy S10
I have sold the truck and can't remember - is there supposed to be a light on when in 2wd? If yes, and you don't even have that light on, it could be a bad switch or wiring. Private message me your email if you want the wiring diagram. I might still be able to find it for you.
there is a ball switch on other side of actuator cable on top of the passenger side axle near front differancel that sticks and make the lights stay on. there should be a two wire electrical connecter coming off this switch. $20 item
got a 01 s10 . replace vacuum actuator, works fine , but still no 4x4 working? got any idea. thinking the differential might not be locking in, what do you think?
I have a 2002 Chevy S10, the actuator when out, i replaced it and now every time i want to use 4x4 the actuator keeps getting ripped apart, do you know what would cause the actuator to keep getting ripped apart?
I have a 1998 chevy s10. Any time I hook up my actuator, it locks it in to 4 wheel drive. It WILL NOT come back out of 4 wheel drive unless I manually unhook it. I already tried swapping the electric button mech. Any suggestions?
i have 98 sonoma the problem is when am driving the 4x4 kicks in we can hear the noise and anytime whem i crank the truck or when am driving the 4x4 kicks in but the button shows am in 2wd do you know what is the problem??? Thank you
My 94 4.3 activated the 4wd using vacuum. The transfer case had vacuum lines that went to the actuator by the front diff. Check that those lines are connected and not chafed. It is always possible the dash switch is faulty or the wiring. Trace it starting there. Let us know what you find..
my 98 blazer is stuck on 4hi i connot get it to go into 2hi do you know what might be the problem? also i cant shift to 4lo. there is a vacuum line on top of the transfer case that had been plugged by the previous owner its actually three lines in triangle formation but only one was plugged. i unplugged it and now its on 4hi constant any help from anyone is welcomed, thank you.
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it is feedback like this that confirms the efforts I spend making/posting videos are worth it... glad it helped you.
I agree! Hate push button 4x4. I also have a clean stock Blazer ZR2 & my rubber on the actuator cracks or breaks every 4-6 months. It’s below my battery & all is stock. It’s clear from any objects, etc. but still goes bad often. I bought mine at O’Riellys & came with a lifetime warranty. I’m on my 5th actuator now in the past 1 1/2yrs. I just keep taking it back & getting a free replacement
THANK YOU! Found the same rubber seal ripped on mine. I'm tight on money and couldn't afford to take it somewhere. Ill be able to take an extra beach trip this summer!
I had an '84 pickup. Put 200k miles on it with zero drivetrain issues. Not even a u-joint. And I even auto-crossed it several times. I ran it in 4x4 low on dry pavement to take advantage of gearing and traction that were better suited to the course.
Terrible.
@amazingaustin16 yes... the lights in the dash indicated 4wd HI or 4wd low. the front drive shaft was spinning but the front differential was not engaged because the rubber vacuum actuator had a rip in the diaphragm... get a friend to operate the 4wd buttons in the cab while you are watching the actuator... you will need to remove the battery and battery tray and use jumper cables to power the truck 4 this test.
I have disconnected the vacuum actuator tube and capped it, and haven't had the noise since, I will eventually get the vacuum switch replaced. I think that the vacuum leaks/builds up over time while driving and the vacuum builds up in the actuator eventually causing the preengagement grinding sound, but I do hear like a gear humming sound,not grinding now, thanks for telling me about the front differential fluid, I didn't even know there was fluid there, I will have to check that out.
This video was relevant for me, and I'm replacing the cable on my 84 S10 Blazer.. The only difference was that my 4WD actuator is mounted on the top of the inner fender well instead of under the battery. Very useful though, i would have had no idea about the side of the cable that connects to the axle.
The spring is inside the vacuum actuator and it pulls on the cable as it should. I disconnected the vacuum tube, and haven't heard the grinding since. Thanks for your help.
Manual states you can put it in 4 HI while moving at any speed, but must be in Neutral to engage 4 LO. My S10 won't let you go to 4 LO when your in gear.
Good video. Very informative. I learned a few things.
Bless You Man! Finally found my issue and it is ripped! Thanks for a solution which is hard to find
i have a 95 4x4 blazer .i have checked the accuator it is in good shape the cable seems to be releasing like it should .but on ice cant get it to lock in either 4 hi or 4lo .no sure where all 3 hoses go to from th vacuum switch .took the switch out and tested it had good voltage.
alright well my only question left is how do i properly hook up jumper cables to a truck with no bettery? just hook them to the terminals?
@amazingaustin16 you got it. make sure you don't weld the + cable to the fender of the truck... tie a shirt around the jumper cable clamp or put a piece of cardboard on top of the fender...
i think there is a spring that by default (when not in 4wd) pushes the gears apart in the front end to keep them disengaged. when you put it in 4wd, the vacuum actuator pushes a gear (that slides) against the spring and then the 2 gears engage. It sounds to me like your spring is tired/worn and over the course of a day, the gear that slides is moving towards the other gear.
i know there was a recall on the switch in the front differential that (I assume) detected if it was locked in or out. Maybe this is bad on your truck. Also, make sure you figure out if it is your transfer case and/or your front diff locked in... this may help you diag the issue. if front diff is locked in, the cable to your vacuum solenoid could be chaffed and rusty. if it is your transfer case, you may have a bad transfer case motor... can you hear the motor spinning?
I know this is a old video but how about this one, I need help. My truck is stuck in 4 low. When I push 2 hi or 4 high I hear clicks and the lights blink then shut off. I checked the lines and made sure everything was hooked up right, fixed any leaks etc etc. I have vacuum to the actuator. Its closed tight but I can't seem to get it out of 4 low. I don't even care about having 4 wheel right now. I just need it in 2 wheel so I can drive the thing on the highway and not mess anything up.... I replaced the switch by the transfer case, added dif oil, checked the cable for a break and nothing. I just don't understand why even when no vacuum is hooked to the actuator why will it not release that cable and manually put it in 2 wheel mode... I'm thinking about buying another actuator but I'm tired of wasted money. The actuator looks good like I said it does have vacuum and closes and when I release the vacuum it does expand..... Someone help. I looked at forms and everything else but nothing has worked ...
Excelente
I have had this issue with 4wd lo and sometimes 4wd hi... The trick I was told was to get it onto a slope and roll it downhill in Neutral. then press the 2wd button and it should shift out. It did for me. I occasionally get all sorts of crazy torque on the rear wheels. The rear wheel spins like it is off the ground. I looked at the piece mentioned in this video and in anouther vid. It doens't move very freely and the cable spring is rusted to hell.
Great video! Have a 4wd problem with my 98 S10 Will def. check out the vacuum actuator & cable, Thanks!
this process is really hard on the gears and electric motor in the transfer case. try to diag if the transfer case is working by putting it in 4Low. if you drive in 2wd but really slow, the transfer case is working and the problem is your front axle. I had this situation once and it was the front axle vacuum actuator that had failed. replaced it and same problem a month later but this time the cable slipped off the actuator.
I would guess you have the gears binding on the transfer case shaft. It would be interesting to remove the motor and try to actuate the gear change yourself using a screw driver or other implement. You may find it extremely difficult to shift. Was the transfer case ever too low on fluid? If it is binding, unfortunately it would likely need to come apart and have parts or shims or something replaced to resolve the problem.
I have a 95 Jimmy and it made a horrible grinding noise unless I put it in 4wd and took it back out, finally figured out my front diff was leaking fluid, filled it up and the problem went away. Still need to change my seal but maybe thats whats wrong with yours as well.
Hi there dstorm3. It is very unfortunate but most 4wd systems really only easily go in and out of 4wd when the vehcile is slowly rolling. when i put mine in/out, I try to get it rolling about 5km/hr in neutral. with this condition, the gears in the transfer case and front end are not under stress and can easily mesh. Unfortunately when you get stuck, this gear meshing is much harder and requires you to be gently spin rear wheels while the electric motor/vacuum actuator are trying to engage.
@mrsillyman....when your actuator went bad did the dash lights still imdicate you were in.4wd? thats what mine is doing..also the front driveshaft spins in 4wd but power ist transfered to the front wheels
I know this is a long time ago, but i have new transfer case motor, new push buttons, have had the vacuum diagnosed and there is pressure, my lights on dash also show it is working along with the transmission acting according to whether im in 4Lo or 4Hi., the computer box is telling the transfer case motor to work. So it's tricky to me. I'll have to find actuator but i don't know what else to look at because everything is appearing to work when diagnosed by myself or mechanic.
Fun ah fun lol thanks for the video though. Would you know what a bad differential feels like?
Vibration, Jerry motion, howling are symptoms of a bad diff. Change your fluid and see what that reveals.
was the ball valve the one mounted directly to the transfer case? i think it has like 3 or 4 vacuum lines coming out of it.
yes, 3 lines
My 91 Jimmy is making a grinding noise even with this vacuum actuator disconnected. Someone said the noise was from the front wheel partially engaging, and thats why I disconnected the vacuum actuator. Strange thing was I disconnected this last time when I had this problem and it worked for like 2 years without any noise, then I had the vacuum switch replaced figuring the switch was leaking vacuum into the actuator and had no problem for like 3 weeks, but now the grinding noise came back even though the actuator is disconnected. But noise goes away when I shift into 4WD? What should I do?
I really need someone to reply to this comment. I’ve replaced the vacuum switch on the transfer case. I’ve checked all the hoses. The actuator is fine. The only thing I know that’s for sure messed up are the buttons themselves but I can get those to work enough to press them. The actuator is always fully sucked and has the cable pulled at all times yet the front wheels aren’t engaged. And when I press the buttons, all I get is a clicking in the differential and a whole lot of nothing after that. What do I do?
Jack it up the front wheels off of the ground. put it in 2wd. crawl under the truck and manually spin the drive shaft between the transfer case and front diff. From memory, I think it should spin freely. Next, put it in 4wd. Now try to spin the same shaft. It should not spin freely now. This should rule out your transfer case. next, with it in 4wd, rotate one of the front wheels. the other front wheel should rotate the opposite way. if the other front wheel does not spin, your front diff is not engaging. get someone to put it in and out of 4wd while you are watching the vacuum accurator. If the actuator moves when 2->4wd and 4wd->2wd, it isn't your electronics, switches or vacuum lines and is likely your front diff.
My problem is that the 4WD drive is grinding, and seems to be trying to engage itself, could the vacuum switch be leaking vacuum to the vacuum actuator? I have a 91 GMC Jimmy with the original rubber, and that works and is not ripped, but its scarry to hear grinding to start at 50 mph. Or what could cause this grinding with the 4WD? I know its the 4WD because if I engage it and disgengage it goes away for a day. Thanks
would the vacuum be in the same place on a chevy silverado 1990 cause im having issues also with my 4 wheel it wont engage at all it's stuck in 2 wheel stick shift wont move ,so im wondering if it's the vacuum or is it that little bolt or both .any help is very apprieciated. thanks
all that boot does is pull the cable which moves the collar into 4wheel drive?
yep
My 01 gmc jimmy s15 series will get stuck in 4hi and wont go into any other gear besides auto 4wheel , changed transfer case motor still wont get out of 4hi i can hear the actuator motor working when i push the button on the dash and can hear the tccm clicking under the dash. have u ever encountered any problems like this before any help would be aprecciated
You wouldn’t happen to have a copy of the hose daiagramfor the four weel drive or could you do a video of the full vacuum hose lay out
Hi. Sorry I don't have a diagram but recall some of the vacuum lines going to the transfer case. Trace those lines and it should be obvious where they go.
www.s10forum.com/threads/the-4x4-vacuum-thread.327817/
great resource
My switch will not light up, also is there some sort of relay that clicks to actuate the vacuum valve in the dash? My fuse is good. I have a 1994 Chevy S10
I have sold the truck and can't remember - is there supposed to be a light on when in 2wd? If yes, and you don't even have that light on, it could be a bad switch or wiring. Private message me your email if you want the wiring diagram. I might still be able to find it for you.
I have a 1995 s10 pickup 4x4. and it dose the same thing .dose not light up.
its a burnt out bulb is all
Good one Thanks
i have a 2002 sonoma 4 door 4x4. the 4x4, switch lights stay all on. what could be the problem?
there is a ball switch on other side of actuator cable on top of the passenger side axle near front differancel that sticks and make the lights stay on. there should be a two wire electrical connecter coming off this switch. $20 item
got a 01 s10 . replace vacuum actuator, works fine , but still no 4x4 working? got any idea. thinking the differential might not be locking in, what do you think?
cable not working or disconnected on other side OR one of the axle's has slipped out 1/4" due to worn c clip. this will cause front diff not to work.
I have a 2002 Chevy S10, the actuator when out, i replaced it and now every time i want to use 4x4 the actuator keeps getting ripped apart, do you know what would cause the actuator to keep getting ripped apart?
You are getting transmision oil into it through the vacuum line, need to replace transfer case seal
yes you are right. happed to me on 3 different s-10's
I have a 1998 chevy s10. Any time I hook up my actuator, it locks it in to 4 wheel drive. It WILL NOT come back out of 4 wheel drive unless I manually unhook it.
I already tried swapping the electric button mech. Any suggestions?
AustralianCroc having the same problem. Find out the problem?
Could be a short in the line. They run close to the exhaust manifold. Or check the switch thats mounted on the gearbox
i have 98 sonoma the problem is when am driving the 4x4 kicks in we can hear the noise and anytime whem i crank the truck or when am driving the 4x4 kicks in but the button shows am in 2wd do you know what is the problem??? Thank you
My 94 4.3 activated the 4wd using vacuum. The transfer case had vacuum lines that went to the actuator by the front diff. Check that those lines are connected and not chafed. It is always possible the dash switch is faulty or the wiring. Trace it starting there. Let us know what you find..
i checked for that vacuum but on my chevy 90it's not there a am clueless on where to check next or what to do next
there is a ball vacuum switch on drivers side transfer case that is bad. $20 at oriellys
Mine lasted 21 years. Then it went. The buttons on the dash and the stupid part that goes on the transfer case
I need to know where the vacume line gose to it fell off on the other end
Kent Wilson man I have the same problem and can't for the life of me find where the hose goes
thc3 saw a video that showed a solenoid above the distributor think it was a S10 though .
Believe it goes to a 3 way valve on top of the transfer case
my 98 blazer is stuck on 4hi i connot get it to go into 2hi do you know what might be the problem? also i cant shift to 4lo. there is a vacuum line on top of the transfer case that had been plugged by the previous owner its actually three lines in triangle formation but only one was plugged. i unplugged it and now its on 4hi constant any help from anyone is welcomed, thank you.
@emmy6423 at 3:50 in my video I describe how to determine if it is your transfer case or front differential that is the problem. start threre
I totally Like your interpretation on diagnosing weather the transfer case is functioning. good video. Inspired me not to give up yet..
can anyone tell me where the vacuum hose hooks to that goes to the accurater. under the battery carrier?
On the back side of the actuator toward the front of the vehicle flashlight might be useful locating it .
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