Question about 1988 Chevrolet K1500
Ok I know this question is old but for any one else who has this problem, I want to clear some info up. GM did not use vacuum on the 4x4 systems on the full size series. Only used on the S series (S10, S Blazers). Here is how to accurately trouble shoot these problems with the full size 4x4. Remove the front actuator from the front axle ( keep it plugged up and let it hang). Put the T-Case in 4x4 Hi or Lo doesn't matter. Turn key on (don't start the engine) . Now check the actuator to see if it has extended. If (no) now check the plug to see if you have current . If you have current to the plug, change the actuator. Problem solved. If no current to the plug. Check for broken wires ( fix if any) If no broken wires. There is another switch on the T-Case that sends power to the actuator Replace it.. Back to the actuator.... If everything checked out and actuator works. With the T-Case locked in 4x4, try to turn the front drive shaft by hand. With the T-Case locked in 4x4 you shouldn't be able to turn the drive shaft. If drive shaft doesnt turn the T-Case is in good shape and the problem will be in the front differential. In these cases the most common problem is an exploded thrust washer. At this point the front differential needs to be rebuilt. Back to the T-Case..... With the T-Case locked in 4x4, if the drive shaft spins, the problem will be in the T-Case and at this point the T-Case will need rebuilt......... I hope you get the information you need to troubleshoot the GM 4x4 issues.
Posted on Mar 31, 2013
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Posted on Jan 02, 2017
there should be a diaphram under the battery that connects to a cable this is vacuum operated but you can also pull back on to engage the front diff.
Posted on Nov 20, 2010
SOURCE: front differential problem
well if it is the vacuum actuator then, i'll explain how to fix it. But first it is a vacuum controlled diaphram that is located under your battery. All you do is take your battery out, you'll need a 5/16 wrench or and 8mm to disconnect the battery connections. Then get yourself a 3/8s drive wratchet and a 8 inch extension,a 1/2 deep well socket to take the battery hold down off, which is directly down from your battery on the side faceing your window. Then after your batterry is out there is a pan that your battery was sitting on now use your 1/2 socket and your wratchet and take that pan out. then you will see this round black thing with 3 6mm bolts holding it on take that out and disconnect the cable going into it is just a little clip holding that on. Then disconnect the vacuum hose going to that it just pulls off. then take that to your junkyard and ask for a new one or go to a parts store if you have any more questions just ask
Posted on Jan 30, 2009
SOURCE: my 1996 chevy silverado front
Yep,unplug it ,unscrew it ,plug it back in engage the 4x4 and watch,the piston should come out in like 2 seconds,kinda slowly ,it's a heated gas that extends it. Should come out with enough power to make it hard to stop with your hands. If it does come out,that's trouble ,shim out of place in the diff,
If it doesn't extend at all or only an inch or so ,it's the actuator. Should extend out far enough to make the rubber boot "wrinkle free".
If the actuator is ok,the axle housing has to come out.
If the truck is jacked up you can take the actuator out and engage the axle with a screwdriver or whatever ,just push on the piston where the actuator pushes ,should slide right in,only a small spring aginst it.
Posted on Mar 13, 2011
If the ground wires from the headlamps are securely tight without any corrosion I suggest the headlamp switch in you van is at fault
Posted on Jul 26, 2011
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