Question about GMC Sonoma

1 Answer

Transfer case problems on a 2000 GMC Sonoma 4x4 sls 5-speed manual tranny -- 4.3 litres engine. 3-way switch. History -- over the past 4 years in winter, wouldn't switch into 4high setting for 4x4. Drove for a bit and then when warmed up or moving switched back and forth normally. Last winter ago, switched into 4 high ( 4x4) and terrible sounding gear noises resulted when stepping on gas. Down hill at a coast no noise ( only under load ). Jacking up vehicle and running all 4 tires ( 4x4 ) revealed no noise or issues -- works just fine. Disconnected drive line to front differential and noises all gone except for when shifting into 4x4 high -- rattling noises occurs but vehicle runs. For the past 4 months just been using the truck as a 2-wheel drive setting. Now, the rattling occurs of late in either setting -- sometimes less in the 4x4 setting than the 2-wheel setting. Also, it jumps into 4x4 setting by itself after a loud noise from the transfer case. Remember, this is all happening with no drive line attached to the front differental. I assume it is either a broken gear tooth OR the engagement motor is not fully meshing but only partially meshing the engagement gears. That's why it all ran fine when no load was present. Could replaceing the engagement motor do the trick or could there also be damage to the complete transfer case? Should I just replace it all to be certain? I found a used transfer case foe $250.00 with 145,000 kms on it. Perhaps that is the way to go? Thanks Chasrles

Posted by on

  • charphil Jul 16, 2010

    Superb response time and the solution was understandable and relevant to the case. Thanks for your time and efforts.



1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • GMC Master
  • 11,800 Answers

Since the noise appears only at load it means that the bearing supporting the front shaft is pretty much destroyed. There is no noise when there's no load because the few remaining ball from the bearing are still doing what they can to keep the shaft centered. When load is applied the balls are pushed aside and the shaft goes off center and starts to rattle in the bearing cage. The deviation of the shaft might be large enough to put sufficient pressure on the control fork forcing it to engage the 4x4 high.
The entire case has been severely damaged and your only reasonable action is to replace it. 
I found a used transfer case foe $250.00 with 145,000 kms on it - that's an excellent price, get it and replace your own.

Posted on Jul 15, 2010

  • charphil Jul 15, 2010

    Thanks, sounds excellent. Where can I get a schematic of the transmission and transfer case or some steps to replace?

    Is the transfer case separately lubricated from the transmission -- didn't see a drain plug for the transfer case apart from the transmission.

    Can it be removed fairly easily from the transmission?

    I am quite adept at repairing dirt bikes and have replaced bearings, clutches and engine components. Perhaps this is something I should not venture into?

    Thanks again


  • Azrael SRL Jul 15, 2010

    Yes , the transfer case is completely separated from the transmission case, with its own lubrication.

    Yes. it can be removed quite easily without any special tools. Yes, you should try to fix it, if you have already bought a replacement part you can at least train yourself and gain experience on it even if it's beyond repair.
    Repair manual



1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
New users get to try the service completely Free afterwhich it costs $6 per call and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

Firing order on a 2000 gmc Sonoma v/6

Shelia, 2000 gmc Sonoma v/6 Firing order, firing order for the 4.3L engine is 1-6-5-4-3-2.
Cylinder order drivers side 1-3-5 and passenger side 2-4-6,
Check the attached links,instruction and guides, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."

4 3L firing order 1982 2005 Chevrolet 10 Blazer GMC S15 Sonoma Jimmy
Chevy Firing Order
2000 gmc Sonoma 6 Firing order Google Search

Aug 20, 2016 | GMC Sonoma Cars & Trucks

1 Answer

Gmc Sonoma Problems

Throttle control valve. Take it out and clean it with electrical contact cleaner or replace it.

Apr 23, 2017 | Cars & Trucks

1 Answer

Is my 1995 GMC Sonoma 4x4 a half ton truck

small trucks like that are considered 1/4 ton. silverado 1500 1/2 ton an silverado 2500 3/4 and up. same goes for gmc

Apr 06, 2013 | 1995 GMC Sonoma

1 Answer

I have a 2000 jeep wrangler, 4.0L 6 cyl. what would be the fluid capacities for the transmission and the transfer case?

If you have the automatic trans it takes 3.8 litres of fluid if doing a service with the filter. If you drain the torque converter (usually only on a tranny swap or new install) it takes 4.7 litres if it is the 30RH tranny and 6.4 litres if it is the 32RH tranny (call the dealer with your vin number to find out which one you have).

If you have a manual trans it takes 2.3 litres.

As for the transfer case there are 4 different transfer cases used that year.

NP242 takes 1.4 litres
NP247 and NP249 take 1.6 litres
NP213 takes 1 litre

Again you can call the dealer with your vin to see what transfer case you have if you don't know.

Feb 27, 2011 | 2000 Jeep Wrangler

1 Answer

I have a 2000 GMC sonoma 4x4. When I try to switch from 2wd to 4wd lo or hi it won't switch most of the time or if it does go into 4wd it doesn't want to switch back to 2wd. I have replaced the motor on...

im not sure if u can switch it to manual but behind the pass side kick panel is the 4x4 mod. the wires going to it are going to broke check all the wires repair them and your problem willl be fixed

Dec 03, 2010 | 2005 GMC Sierra

3 Answers

My 2000 gmc jimmy 4x4 stoped working. It wont go into 4 hi. the vacume pump under the battery is good. can hear and feel the motor switch from 4 low to 2 hi. any ideas? Is there a code reader for this...

Hi, it sounds like your front diff engages but your transfer case is not. raise one of your front tires off the ground and see if it will lock up when you go to 4hi. If it does then the problem is your encoder motor that hangs down under your transfer case.

Aug 21, 2010 | 2000 GMC Jimmy

1 Answer

For 4x4 gmc sonoma is the 4 wheel drive light is always supposed to be on

It's only suppose to be on when the 4WD is in use and should be off when in 2WD. If the light is on, replace the 4WD switch on top of the transfer case, drivers side. You can pick up the vacuum switch at Auto Zone, Napa for around $25.00 and is common to fail. When they fail, the vacuum to the front axle hub actuator will stay engaged and the axle will always be engaged. it's a simple fix and should take you 15min to replace if you can get under the Sonoma with out jacking it up off the ground.

Disconnect the vacuum line from the switch and unscrew the switch out from the transfer case with a 3/4 inch wrench i believe. No need to worry about Teflon tape, the switch is tapered and will not leak fluid.

Good luck and thank you for using Fixya.

Feb 23, 2010 | 1992 GMC Sonoma

1 Answer

1998 gmc sonoma push button 4x4 busting diaphram vacuum actuator

On top of the transfer case is a vacuum switch with 3 vacuum lines connected to it. This switch controls when vacuum is applied to the vacuum actuator. This switch can fail partly and allow fluid from the transfer case to be sucked up into the vacuum lines and anything connected to them as well. When you replaced the actuator before, did you notice any oily fluid inside of it?

Dec 10, 2008 | 1996 GMC Sonoma

Not finding what you are looking for?
Cars & Trucks Logo

Related Topics:

137 people viewed this question

Ask a Question

Usually answered in minutes!

Top GMC Experts


Level 3 Expert

76649 Answers


Level 3 Expert

1311 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22219 Answers

Are you a GMC Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides