Electronic 4x4 wont engage 2 vehicles


  #1  
Old 02-08-04, 05:01 PM
SteelPanther
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Electronic 4x4 wont engage 2 vehicles

I have 2 4x4 vehicles with the same problem.

First a 1994 GMC Jimmy 4x4 4.3 L Vortec v6- Automatic Tranny/hubs

4x4 worked fine one night then we got in and went to go to work the next day and I pushed the button for 4 HI when leaving our driveway because it is a steeper grade and icy with a stop sign at the top. but instead of engaging the green light just blinks and something in the dash by the glovebox clicks but 4x4 wont engage, Ive tried it multiple times now but no luck. it will nto go into 4 low either. Weird because it worked the night before when I used it. I did check the TCCC fuse 5 amp and it was fine.

2nd 1994 Ford Bronco 4x4 302 V8 Automatic Tranny/hubs

Same probem as described above the Bronco has electric shift 4x4 as well. Same results 4x4 will not engage just clicks and shuts off. This was used about a month ago and worked fine then as well.

Could it be the cold weather? Ive tried it sitting still and at 20mph in both. Truely confusing how both would all of a sudden take leave on me without notice. Thanks. James.
 
  #2  
Old 02-09-04, 05:57 AM
K
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try this www.glue.umd.edu/~singletn/exp.html
go to transfere case section. worked for me. took about 45 minutes to fix and didnt cost a dime.
 
  #3  
Old 02-09-04, 11:15 AM
SteelPanther
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Thanks Kerry!!! Ill give that a looking in to. Very good info there.
 
  #4  
Old 02-10-04, 07:35 AM
K
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let us know what you find. hope its only a minor problem. good luck!
 
  #5  
Old 02-10-04, 04:34 PM
frank997
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Re: Electronic 4x4 wont engage 2 vehicles

Originally posted by SteelPanther
I have 2 4x4 vehicles with the same problem.

First a 1994 GMC Jimmy 4x4 4.3 L Vortec v6- Automatic Tranny/hubs

4x4 worked fine one night then we got in and went to go to work the next day and I pushed the button for 4 HI when leaving our driveway because it is a steeper grade and icy with a stop sign at the top. but instead of engaging the green light just blinks and something in the dash by the glovebox clicks but 4x4 wont engage, Ive tried it multiple times now but no luck. it will nto go into 4 low either. Weird because it worked the night before when I used it. I did check the TCCC fuse 5 amp and it was fine.

2nd 1994 Ford Bronco 4x4 302 V8 Automatic Tranny/hubs

Same probem as described above the Bronco has electric shift 4x4 as well. Same results 4x4 will not engage just clicks and shuts off. This was used about a month ago and worked fine then as well.

Could it be the cold weather? Ive tried it sitting still and at 20mph in both. Truely confusing how both would all of a sudden take leave on me without notice. Thanks. James.
Biggest thing is the vacuum switch mounted on the front axle. They get gummed up and it won't open. You take it off and soak it in denatured alochol. Lightly blow it dry (5psi no more) and reinstall it. If it is gummed up so bad replace it. This peice has three vacuum lines to it and it about as big as your thumb. Frank
 
  #6  
Old 02-11-04, 11:22 AM
SteelPanther
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Hi Frank,

Id like to give that a try too. How do I remove that switch? Is it threaded into the axle? (On the Bronco im guessing you meant?) the Jimmy has independant susp in the front would it be on the Jimmy as well? Ill be giving it all a try this weekend so suggestions are appreciated. Thanks again.
 
  #7  
Old 02-11-04, 02:12 PM
D
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On the jimmy the front axle actuator is under the battery thats where I'd look to see if corrosion rotted the cable off or the vacuum hose is off.While in there check for vacuum at the hose the vacuum switch is on top of the transfer case driver's side.Sounds to me like you have a shift motor problem though.Disconnect the battery for a couple minutes and see if it shifts into 4x4.
 
  #8  
Old 02-12-04, 01:45 PM
SteelPanther
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Thanks for the extra info Davo. Ill post my results as soon as I find the problem.
 
  #9  
Old 02-14-04, 06:06 PM
SteelPanther
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Alright i took off the battery, and battery box. Underneath was the actuator/vacuum line. All seemed to be hooked up like it should be with a vacuum hose running to the back of that diaphram. And the cable running from it to the front axle. I took the hose off and replaced the battery and it did have vacuum. I dont have a vacuum test kit but it sucked to my thumb and wouldnt fall off.

What is this diaphragm supposed to look like at its normal stage? the rubber boot was all wrinkled and sucked in of sorts. I guees my question is when 4x4 is engaged is the cable supposed to be pulled? or pushed by the rubber boot? With the vacuum hose removed I tried to move the cable by hand with no luck pretty solid couldnt get it to move either way.

That is my results on the Jimmy/actuator under the battery box. If that all sounds as normal where would I go from there? Is there a way i can remove the shift motor and test it? Is there any type of diagrams I could find online to take a look?

Thanks
 
  #10  
Old 02-14-04, 08:36 PM
champ98
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I would have to agree with Davo about the shift motor problem on your Jimmy 4x4. I had a 93 Blazer 4x4 that would not shift into 4 wheel drive. I had the dealership scan the computer codes and it showed a code indicating a problem with the shift motor. They wanted $400 for a motor plus labor but I got one at a junkyard for $125. After they installed it and reset the codes, my 4x4 worked like new!
 
  #11  
Old 02-15-04, 05:14 PM
SteelPanther
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Alright, GMC Jimmy. Went under the vehicle ad had soemone press the 4x4 button. motor engaged and turned. Wanted to make sure the gears were actually turning inside so I removed it so I could see for sdure. Motor and gears were turning but upon reassembly it does not want to slide back o to the shaft coming out of the T Case? Any ideas on what is the best way to get it back on? I shifted it around into different postions but it will only go on about 1/4 way.
 
  #12  
Old 02-16-04, 10:14 AM
SteelPanther
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My two main problems, I'm out working on the Jimmy right now because its about 20 degrees out today!! Warm compared to last nights -10.

#1 After verifying my encoder motor worked now it wont go back on to the transfer case.

#2 I dont know how to test the actuator to see if it works to engage the front axle. Should I be able to pull it in and out with a pliers or something of the nature to engage and disengage the axle? What position should it be in at rest in 2wd?

Thanks.
 
  #13  
Old 02-16-04, 10:45 PM
mike from nj
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this is a good place for

a

service manual!!



it would describe everything pretty clearly, and tell you how to position the motor (how to 'time' it) to reinstall it correctly. you are taking the chance of breaking someting, by doing it wrong.

if it was engaging the gears inside, it would be locking and unlocking the front driveshaft, that's easier than removing the encoder motor to check.

(other vehicles use that same system, and i know that the system needs to be aligned properly to get it back together)

ps. what ever fixed your rodeo with the no blower motor working???
 
  #14  
Old 02-16-04, 11:43 PM
SteelPanther
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Hi Mike,

Thanks for the reply. I have bought every book related to my GMC. In the way of Haynes/Chiltons, and just spent about $40.00 in books Im not able to return because none of them describe any procedures with the transfer case motor. They all seem to deal with manual engagement of the transfer case, no electric. Bad part is once you remove the plastic wrapping around the book no el returno.

I offer this as a helpful insight if you are going to buy a book dealing with your GMC transfer case encoder motor do not buy:

Haynes 24070: 83-94 Jimmy
Chilton 28862 S series pickups and SUVs 1994-1999.

They do contain valuable info which Im glad to have but not one of them mentions a peep of an encoder motor/transfer case motor, like they dont exist.

On the Rodeo- Sorry i lost the post and I didnt know how to refind it. I had tot ake apart the steering column on the Rodeo the wire had broke just below the ignition switch but after going through the wiring from CB box all the way inside I found the break in the column. Last place I had looked because I didnt think the break would be there since it didnt have tilt wheel. But that was the answer.

What other manuals should I look for to get the correct procedure? I really cant spend too much more on books after today

So after I get this back together if the encoder motor is turning the gears inside i will not be able to turn the DS by hand with the wheels off the ground and the vehicle in park correct? I guess I did this a little backwards, but im still learning yet If the encoder motor puts the transfer case into 4x4 why does my light flash and go off? Would this happen just from the front axle not engagin?
 
  #15  
Old 02-17-04, 03:17 PM
D
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If you have a diagnostic code in the transfer case module it may not complete a shift or the encoder motor is bad.The motor contains a position switch also which may be bad.Disconnect the battery or the courtesy lamp fuse for a couple minutes and try again.If you can't bolt the encoder motor back on you may need to move the transfer case lug to match the motor or run the motor again to get it back on.Btw the transfer case should be in 2wd when removing the motor to replace it.
 
  #16  
Old 02-17-04, 03:43 PM
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If you have it off the ground try putting it in 4 wd and see if the front shaft turns if it does the encoder motor shifted the case.
 
  #17  
Old 02-17-04, 07:42 PM
SteelPanther
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I have found the problem with the Jimmy 4x4. it turns out the main gear was split in half inside of the encoder motor. Ill describe my whole process here may not be the correct way but this is the way I did it.

1. Removed front drive shaft from transfer case yoke and collapsed it forward to get a little extra room. (Remember to mark the shaft/yoke for correct reinstallation unless your going to put in a new U joint while you are down there.)

2. Removed the three retaining bolts on the encoder motor, 2 on the sides one on the very top you can barely see. these were 10mm for reference may differ.

3. The encoder motor was then loose, I moved it towards the yoke away from the shifting shaft. I could then kind of stick my finger inside to see if the gears were turning while a assistant pressed the 4x4 button. They may turn but they may not be strong enough as was the case with my encoder motor.

4. I slid it as far away from the shift shaft as possible. Then used a small pry bar and pryed it forward and it popped free and i was able to move it easily. This only took a SLIGHT amount of pressure. Do not pry hard because it is a fairly weak case.

5. I then had it doqwn under the vehicle so I could see inside the shifting shaft mating hole. I had an assistant once again engage the 4x4 and with the motor being off and closer and by watching the gears fidget I could tell there was damage inside.

6. Removed the retaining bolt from the wiring connector so i could remove it. This was an 8mm.

7. I took the 2 recessed torx screws out of the case. You only need to remove these two screws and possibly the ones holding on the dust cover over the engine as well. Dont worry about the funny looking torx type with the circles in the middle these arent important for opening the case.

8. Pry at the pry points on the case that are molded. i wouldnt recommend prying anywhere else but you may need to as you need to split the case fairly evenly for it to come apart.

That was where I dsicovered the main gear coming off the motor was split in two and was turning the gears but, when torque actually got applied they could have never shifted the transfer case.

I did take photos of the whole event step by step and am going to post a small website dealing with the S15 Jimmy encoder motor as it seems to be a really common problem that people need help dealing with.

I picked up a spare encoder motor for 25.00 that im just going to salvage the main gear out of. As mine is in fairly good condition compared to the other with the exception of my main gear.

On to the Bronco!!!!
 
  #18  
Old 02-20-04, 02:55 PM
SteelPanther
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Bronco problem solved.

The transfer case motor just needed a good clean out. After removing itand taking a look it was pretty gummed up. After cleaning the assembly and reinstalling it the 4x4 worked like a charm.

Probable cause: Mis or non use of 4x4. On talking with the previous owner he stated that he hadnt used the 4x4 in a good 3-4 years not engaging it even once!!

Of both models the Jimmy and the Ford Bronco. Ford definately has the easier system to deal with and make repairs on, do to its location right out in the open. The GMC is alot more of a hassle tucked tightly i behind the driveshaft and front transfer case yoke.

That website I promised earlier... well here is the addy for it, I just started making it but I will add more pictures within a day or two:

http://myrepairs.50megs.com/
 
  #19  
Old 02-20-04, 05:15 PM
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Nice website you have there.I did notice that you state you found no help on the web and figured it out yourself.Is that a fact?I told you twice you had a encoder/shift motor problem.Must feel good to diagnose it yourself.
 
  #20  
Old 02-20-04, 05:58 PM
SteelPanther
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I meant no pictures/diagrams on the web of the encoder motor like there is for Ford ones. I havent found any webpage yet that helps explain how to do the GMC encoder motor I didnt say I diagnosed it myself dont be so sensitive.

Notice I said I found some folks willing to give advice!! If you want me to put your name and number down Id gladly do so.
 
  #21  
Old 02-25-13, 08:39 AM
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Followed but still lost.

Ok, so i am still having similar 4x4 issues, I have a 93 gmc s15 jimmy w/4.3l cpi vortec motor and the electric push button 4wd, mine has the green light for hi and the orange for low. My 4wd is intermittent...meaning it does sometimes work but where im stumped, when i do have lights on the push button, everything about the 4wd, the relay behind glove box etc, works fine, but when i get no lights at the push button, i get absolutely nothing involved w 4wd. Now sometimes i can disconnect the neg batt cable for 20 to 30 min and she works again, this last time, no bueno. I thought that maybe it could be the contacts in the switch so i took it out and cleaned it but still no good. any help would be appreciated,
 

Last edited by Shadeladie; 02-25-13 at 09:22 AM. Reason: Contact info not allowed for your safety
 

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