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1999 GMC Jimmy, 4x4 not engaging front axle


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dustin8420
New User

Jan 16, 2016, 1:20 PM

Post #1 of 11 (1916 views)
1999 GMC Jimmy, 4x4 not engaging front axle Sign In

1999 GMC Jimmy, 4.3 liter engine. So we get no error codes, doesn't seem to have a vacuum leak or a problem with the transfer case, but the front axle doesn't actually engage. We're at a loss for how to diagnose problems any further and we are hoping for more ideas here.

When changing into 4 high the light changes on the dash as if the computer thinks all went well, but the front axle doesn't actually engage. The diaphragm under the battery box seems to to function properly, which means there shouldn't be a vacuum leak or a problem with the switch on the transfer case. So how do we diagnose this further?


gsferraro
Veteran

Jan 16, 2016, 2:30 PM

Post #2 of 11 (1909 views)
Re: 1999 GMC Jimmy, 4x4 not engaging front axle Sign In

Is this a 4 button switch on the dash? So when you hit the 4 high button, does it blink and then stay steady on 4 high?


kev2
Veteran
kev2 profile image

Jan 16, 2016, 3:36 PM

Post #3 of 11 (1903 views)
Re: 1999 GMC Jimmy, 4x4 not engaging front axle Sign In

no flashing 4wd controls, no codes, actuator is moving next I would check cable they are known to snap break- try google - "jimmy 4wd actuator cable" might be a tutorial


dustin8420
New User

Jan 17, 2016, 12:52 PM

Post #4 of 11 (1880 views)
Re: 1999 GMC Jimmy, 4x4 not engaging front axle Sign In

It's a 3 button setup and yes blinks and then stays 4 high (or low).


dustin8420
New User

Jan 17, 2016, 12:58 PM

Post #5 of 11 (1878 views)
Re: 1999 GMC Jimmy, 4x4 not engaging front axle Sign In

Found a perfect video running through the process of checking and replacing the actuator cable. So thank you very much sir! Cool We're replacing the cable regardless of whether it's bad or not, but I will drop a status update later today after I've had time to change it.


dustin8420
New User

Jan 22, 2016, 2:47 PM

Post #6 of 11 (1832 views)
Re: 1999 GMC Jimmy, 4x4 not engaging front axle Sign In

Okay so I had some trouble with the housing that connects the actuator cable to the differential. Bought a new housing, got everything connected and... no dice. Made no difference.


Discretesignals
Ultimate Carjunky / Moderator
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Jan 22, 2016, 4:21 PM

Post #7 of 11 (1824 views)
Re: 1999 GMC Jimmy, 4x4 not engaging front axle Sign In

When someone activates the 4 wheel drive, do you see the actuator diaphragm suck in and pull the cable? Should be able to pull the cable around 3/4 inch.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Jan 22, 2016, 4:30 PM)


gsferraro
Veteran

Jan 27, 2016, 4:12 PM

Post #8 of 11 (1770 views)
Re: 1999 GMC Jimmy, 4x4 not engaging front axle Sign In

I would look at that front actuator, there should be 2 wires going to it. This part has a high failure rate and has been updated. You would have to take the part out(it should unscrew) and bench test it with a 12 volt source, one way the actuator will come out and switch the wires it will go back in. How i test them is, i hold it against my work bench and apply the 12 volts and see if the actuator comes out. (sorry for the late response, is was away)Gary


kev2
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Jan 28, 2016, 8:46 AM

Post #9 of 11 (1753 views)
Re: 1999 GMC Jimmy, 4x4 not engaging front axle Sign In

I think this is a vacuum operated cable actuator - not the electrical as colleague mentions.


In first post OP said NO vacuum leaks (my bad I ASSUMED)- Maybe we should revisit the operation and vacuum apply and routing....


gsferraro
Veteran

Jan 28, 2016, 9:13 AM

Post #10 of 11 (1747 views)
Re: 1999 GMC Jimmy, 4x4 not engaging front axle Sign In

This car has a transfer case control module, right side kick panel


kev2
Veteran
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Jan 28, 2016, 12:28 PM

Post #11 of 11 (1738 views)
Re: 1999 GMC Jimmy, 4x4 not engaging front axle Sign In

  
test trying to add picture


(This post was edited by kev2 on Jan 28, 2016, 12:37 PM)






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