GM Troubleshooting Part 13 - 4WD vacuum actuator & cable diagnosis

This is part 13 of a multi part video series about how to troubleshoot any ignition, fuel injection or timing issue. I tacked on this video about the 4wd system just because I thought it might help someone even though it is unrelated to starting/running the engine.

Category:

Autos & Vehicles

Tags:

• O2
• oxygen
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• S10
• S-10
• starter
• solenoid

[amazingaustin16]

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?

[mrsillyman]

@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...

[amazingaustin16]

@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

[mrsillyman]

@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.

[mrsillyman]

@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

[BIGW0RD]

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.

[mrsillyman]

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.

[mrsillyman]

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.