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GMC Jimmy, SUV
#293 of 313 1997 GMC Jimmy 4x4 no vacuum to actuator.
Dec 10, 2011 (6:48 pm)
I have a 1997 jimmy 4x4 won't engage, front axle does not lock. Thanks to this forum I have found several problems and fixed them. The vac. switch was stuck. I replaced it. The actuator was torn. I replaced it. The dash switch seems to be working fine because the TC does shift and the front driveshaft turns. It also shifts into 4lo. I have removed the vac. switch and pushed the ball up by hand and I get vac. at the actuator hose. I installed a vac. gauge in the actuator hose and observed that when the 4hi button is pushed there is a verry quick jump of the needle to about 4" then it immediately drops to zero again. This occurs whether or not the vehicle is in motion. If I then shift into 4lo nothing happens on the vac. gauge. However, when I shift back to 4hi the vac.reading is 1.5", and stays there until I shift into 2hi. I'm thinking that there is an internal TC problem that is causing the switch to remain down. Has anyone had this problem. Also what does the electric switch on the front differential do. I haven't checked it yet, will do so tomorrow. Thanks for your help.
#294 of 313 Re: 98 Jimmy 4wd problems [revn57]
Dec 11, 2011 (4:39 pm)
Hello revn57, I'm not sure but I think that the vacuum is blocked by the switch on the transfer case and is vented off of the actuator by the same switch . That's what the third hose is for. It is the vent. One hose goes to the engine to supply vacuum. One goes to the actuator to operate the cable. one just goes to the atmosphere to allow the actuator to release vacuum through it.
#295 of 313 Re: 1997 GMC Jimmy 4x4 no vacuum to actuator. [zorad1000]
Dec 12, 2011 (5:13 pm)
I checked the front axle switch, it seems ok. although there is 12 volts at the switch conector. I was expecting 5 volts... I took the new vacuum switch out of the transfer case again and pushed the ball in by hand and rotated the front drive shaft with the engine running and the front wheels turned, so the actuater, cable and axle are ok. I removed the transfer case shift motor and shifted the shaft by hand. The part that pushes the switch up moved as I turned the shaft. I then installed the vacuum switch with the case in 4lo and turned the front driveshaft by hand with the engine running. The front wheels did not turn. My conclusion is that the new switch is defective or wrong. I will get annother switch tomorrow this time from the GMC dealer.
#296 of 313 Re: 1997 GMC Jimmy 4x4 no vacuum to actuator. [zorad1000]
Dec 13, 2011 (5:27 pm)
I fixed mine by changing the encoder motor on the transfer case. It sounded like it was going in but it didnt work sometimes, Hope you get yours fixed soon four wheel drive season is upon us
#297 of 313 Re: 1997 GMC Jimmy 4x4 no vacuum to actuator. [zorad1000]
Dec 15, 2011 (4:22 pm)
I was right. The new switch that I put in saturday was either defective or wrong. I just put in a new OEM switch and the 4wd works perfectly now. Apparently there are two different transfer cases mine is a 233-c I don't know the number of the other case. The part no. for the OEM switch is 89059420 . I will return the defective switch tomorrow for a refund. I hope that my experience with this has helped someone. Lesson learned, use high quality parts the first time. I don't know if the two different cases use two different switches or not, I'll find out tomorrow.
#298 of 313 Re: 2001 GMC Jimmy 4x4 will not shift into 4hi [abbyteed]
Jan 05, 2012 (9:35 am)
Check vacuum line coming off the PVC going to in front of the fire wall drivers side for leaks!
#299 of 313 Re: 1997 GMC Jimmy 4x4 no vacuum to actuator. [zorad1000]
May 02, 2012 (6:57 pm)
Well the actuator has failed again because of trans fluid getting in it . I guess I should have blown out the lines the first time. However I have found a manual cable shift kit for the front axle. I will install this manual shifter cable soon. the kit is available at Summit. costs about $160.
May 03, 2012 (11:40 am)
I recently had some tires swapped over from winter to summer and upon getting a front end alignment I was told 2 bolts were rounded. One on each side and one front and one rear. Is this a hadr fix? Sould I just change the nuts rounded or just change all 4 bolts. How hard is it and what do I need. Thanks Mike
#301 of 313 Re: 1997 GMC Jimmy 4x4 no vacuum to actuator. [zorad1000]
May 05, 2012 (3:47 pm)
my friend trans fluid is getting in because transfercase seal is leaking into your transmission I had to fix mine hope this helps