How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask david Your Own Question
david, Heavy Duty Repair Mechanic
Category: Chevy
Satisfied Customers: 1500
Experience:  Certified Master Technician,Certified in diesel & gasoline engines
Type Your Chevy Question Here...
david is online now
A new question is answered every 9 seconds

99 gmc jimmy 4x4 not working changed vacuum actuator ...

Customer Question

99 gmc jimmy 4x4 not working changed vacuum actuator actuator cable. and dash switch. Still not working the lights on dash do blink and stay on. I did also unplug the vacuum lines from the switch on the firewall also and the service 4x4 light did come on. I did clear the code afterwards. transfer does engage but not the front axles. They do if vehicle is off the ground kind of. Got any other clues...
Submitted: 9 years ago.
Category: Chevy
Expert:  david replied 9 years ago.

thank you for your question hope this helps.

It's either one of 2 things.. It's either the v ac switch on the side of the transfer case, or the encoder motor...I would lean more towards the encoder motor.

there have been means owners with this same problem.

here is how i would go repairing this problem

1. Raise vehicle safely so that you have enough room to work under the drivers side. Always use jack stands or another suitable support for your vehicle.

2. Locate the encoder motor, it will be right next to the front drive shaft yoke on the transfer case. (You will notice a round plastic dust cover going sideways under the transmission)

3. Have an assistant press the 4x4 button so you can listen to see if the motor even moves or if it possibly shifts the transfer case into gear, or you may hear no sound at all, motor dead.

4. removed the front drive shaft for additional room. This thing is in there tight, little or no room to work. Remember to mark your drive shaft for proper re installation with a grease pen etc.

5. be careful so that your bearing caps don't fall off the U joints unless your gonna to replace them.

6. Use a 10mm wrench to loosen and remove the very top bolt holding in the encoder motor. Its way on top and hard to see. you should be able to remove the other two with a socket wrench. (3 in all)

7. To remove the motor pushed the encoder motor farthest away from the transfer case as possible but it still wouldn't come off, but almost. Then used a large screwdriver or pry bar and preyed it forward, VERY GENTLY. If you can remove the front yoke from the transfer case you should have no problems at all.

8. It pop's forward and out. Then have an assistant press the 4x4 button once more while your watching the gear inside the encoder motor. It was fidgeting back and forth so you knew immediately something in not right inside.

9. Remove the wiring harness with an 8mm socket and take the motor to the bench. (no sense in laying on the ground working on it)

10. Remove the torx screws that hold the case together and pried it apart, it is pretty gummed together and there are pry points. I would recommend using the pry points as the case isnt the strongest thing ever made.

11. Inside you will notice the gear coming off the motor was cracked in two but still in place, but no chance of it effectively engaging the transfer case.

Blue= Wiring Harness Connector

Blue= Torx case screws

Gear Assembly-Broken main gear

Broken Main Gear-How it is supposed to look.

i hope this helps you

Customer: replied 9 years ago.
I have checked to see if the transfer does kick in. When vehicle was off the ground and it does. Do you think this is still the problem?
Customer: replied 9 years ago.
Reply to david's Post: That is the same answer as last time and I sent in the first question that the transfer did kick in????
Customer: replied 8 years ago.
I am selling this truck I did change encoder motor no change thanks for trying

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
< Previous | Next >
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland

Meet The Experts:

  • GM Tech (Cam)

    GM Tech (Cam)

    Chevy Technician

    Satisfied Customers:

    GM Grand Master Technician 2007. 14 years experience.
< Last | Next >
  • GM Tech (Cam)'s Avatar

    GM Tech (Cam)

    Chevy Technician

    Satisfied Customers:

    GM Grand Master Technician 2007. 14 years experience.
  • Tim's Auto Repair's Avatar

    Tim's Auto Repair


    Satisfied Customers:

    Have owned a repair shop for 25 yrs.
  • Gary's Avatar


    Chevy Technician

    Satisfied Customers:

    15 years GM master tech
  • Dave Nova's Avatar

    Dave Nova

    Chevrolet Technician

    Satisfied Customers:

    ASE Master Certification. GM World Class Certification
  • John's Avatar


    Master A.S.E Automotive technician

    Satisfied Customers:

    A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
  • Don 'Mo Lurch''s Avatar

    Don 'Mo Lurch'

    Auto Mech / Electronics

    Satisfied Customers:

    Chevrolet Cert., Heavy Line Mech, Race Shop Owner, Mobile Electronics.
  • Ron Z.'s Avatar

    Ron Z.

    - Chevy Tech -

    Satisfied Customers:

    18+yrs experience. State Inspector and Chevy Diagnostics