OHMs question on 4 wd switch

therealfleen

Original poster
Member
Mar 3, 2014
12
I have some issues...."service 4wd" on, switch (on dash) indicator lights not on sometimes, it starts in 4L...etc.

I have a 2003 Chevy suburban 1500 with auto 4wd.

All my ohms check out with specs when buttons are pushed accept for:
1. auto 4wd was at 0.07 (should be 61.6-68.1)
2. 4H was at .66 (should be 656-670...assuming its 656.00 - 670.00)

The switch holds steady at 9.10 with no buttons pushed, which is spec.

I'm kinda outta my area of expertise; not sure how much variance is allowable with the OHM specs.
So.....Do ya think the switch is bad?

Thanks in advance everyone!
 

linneje

Member
Apr 26, 2012
404
Technically, you need to list your units with your values. Is it a coincidence that your measurements are identical to the spec that you listed, if the units on the multimeter happen to be different?

In otherwords, is your display in ohms or kohms??
 

therealfleen

Original poster
Member
Mar 3, 2014
12
linneje said:
Technically, you need to list your units with your values. Is it a coincidence that your measurements are identical to the spec that you listed, if the units on the multimeter happen to be different?

In otherwords, is your display in ohms or kohms??

linneje, thanks for the reply....and, I will try to give you better information.

My meter is set to 20k...so, yes, I believe it Kohms. Here's a pic:


Here are the exact readings when I tested the switch - with it set on 20K:
Normal: 9.10 kohm
Auto: 0.06 kohm
2H: 1.51 kohm
4H: 0.66 kohm
4L: 2.34 kohm

Here are specs I found online:

Normal 8.63-9.54 K ohms
Auto 4 WD 61.7-68.1 ohms
2 HI 1.50-1.53 K ohms
4 HI 656-670 ohms
4 LO 2.32-2.37 K ohms
Neutral 1.015-1.035 Kohms

I notice now that in the above specs that everything is Kohms except Auto and 4H those or just ohm...not sure it that is a typo in the post I copied this from? Or, do I need to switch the meter to something different when I test OHM vs. KOHM? If you look at the pic of my meter, I do see 20M, 200K, 20K, 2000, and 200 for OHM settings...it looks like I need to move that switch on the meter when testing the Auto and 4H?

Yikes, sorry for the ignorance on this one - I'm learning. BUT THANKS FOR THE HELP!:thumbsup::thumbsup:
 

linneje

Member
Apr 26, 2012
404
OK, that is great info now.

All of your readings are within specs if you convert the unit. The 0.06 kOhms is a little inaccurate because you should be using the 2000 Ohm dial for that reading. At the sensitivity you chose, the 0.06 is approx. 60 Ohms, but if you take another reading with the 2000 Ohm sensitivity setting, I would bet it will show a more accurate reading that will fall within range as all of the other test values are within normal specs.

I think that you are going to have to move your troubleshooting away from your switch and look at something like the encoder motor or TCCM, or possibly the wiring. Everything with the switch looks OK.
 

therealfleen

Original poster
Member
Mar 3, 2014
12
linneje said:
OK, that is great info now.

All of your readings are within specs if you convert the unit. The 0.06 kOhms is a little inaccurate because you should be using the 2000 Ohm dial for that reading. At the sensitivity you chose, the 0.06 is approx. 60 Ohms, but if you take another reading with the 2000 Ohm sensitivity setting, I would bet it will show a more accurate reading that will fall within range as all of the other test values are within normal specs.

I think that you are going to have to move your troubleshooting away from your switch and look at something like the encoder motor or TCCM, or possibly the wiring. Everything with the switch looks OK.

And this is why I love forums....:biggrin:
Thank you for the information linneje, I really appreciate it.

The fuses under the hood and inside the cabin are good. I did a soft reset - per online instructions - by pulling the "trek" fuse while the truck was running. No change.

Now, I called the dealer to pick their brains with what'd they give up over the phone, and he said to check the plug connections under the hood on the "module" driverside firewall. Well, I'm not sure where that componenet is, but I pulled all connectiosn in that vacinity and checked them. This true?

Also I looked underneath on what I believe is the transfer case up front to the pass. side of the tranny and see ONE plug on that. I didn't check that yet. Wasn't sure how to get this one off and didn't want to break it. :confused:

Or....this a trip - now - to the dealer/shop?

If this blasted winter wasn't hangin' on down here in MI, well, I may be okay - but I need that 4x4!
 

linneje

Member
Apr 26, 2012
404
Ok, I am not familiar with your truck specifically but I believe the platform is similar in operation to my SUV. What you are referring to, to the right of the tranny on the pass side is the disconnect assembly, and that one electrical connection is the actuator. Judging from the description of your symptoms, it is unlikely to be the disconnect assembly causing the problem.

The transfer case is directly behind the tranny to the rear of the vehicle (down the center of the vehicle, underneath). This will have a motor which controls the operation of the transfer case, called the encoder motor.
Remove/Replace/Rebuild GM 246 transfer case, 2000 Chev Suburban - YouTube
The above link shows you the transfer case. Don't watch the video for the repair, he is doing is a complete rebuild, just watch to get an idea of the location and the encoder motor which is attached to the transfer case.

What you really need at this point is a scan to tell where the problem is coming from - like a GM Tech II scan. This would narrow down the culprit. My guess is either the encoder motor, or the transfer case is seized. Unfortunately a trip to the shop might be unavoidable to at least get a scan. I have a friend who has the expensive scan tool so I can get this for free ... do you know anyone who has an expensive scan tool?
 

therealfleen

Original poster
Member
Mar 3, 2014
12
linneje said:
Ok, I am not familiar with your truck specifically but I believe the platform is similar in operation to my SUV. What you are referring to, to the right of the tranny on the pass side is the disconnect assembly, and that one electrical connection is the actuator. Judging from the description of your symptoms, it is unlikely to be the disconnect assembly causing the problem.

The transfer case is directly behind the tranny to the rear of the vehicle (down the center of the vehicle, underneath). This will have a motor which controls the operation of the transfer case, called the encoder motor.
Remove/Replace/Rebuild GM 246 transfer case, 2000 Chev Suburban - YouTube
The above link shows you the transfer case. Don't watch the video for the repair, he is doing is a complete rebuild, just watch to get an idea of the location and the encoder motor which is attached to the transfer case.

What you really need at this point is a scan to tell where the problem is coming from - like a GM Tech II scan. This would narrow down the culprit. My guess is either the encoder motor, or the transfer case is seized. Unfortunately a trip to the shop might be unavoidable to at least get a scan. I have a friend who has the expensive scan tool so I can get this for free ... do you know anyone who has an expensive scan tool?

Ahhh. Makes sense. I do know a buddy who has the tools. I'll ring him up. Thanks again...I'll keep a post going with updates. You at least saved me $60-$100 on getting a switch I didn't need, so I owe ya!:thumbsup:
 

MAY03LT

Member
Nov 18, 2011
3,412
Delmarva
therealfleen said:
The switch holds steady at 9.10 with no buttons pushed, which is spec.

So.....Do ya think the switch is bad?

Did you try flicking the switch with the meter hooked up? The ohms at rest are usually what goes bonkers when the switch fails.

therealfleen said:
not sure it that is a typo in the post I copied this from?

Not a typo, they are correct.:cool:

linneje nailed it. A scan of the TCCM might be next best step. If your local to me hit me up.
 

linneje

Member
Apr 26, 2012
404
therealfleen said:
Ahhh. Makes sense. I do know a buddy who has the tools. I'll ring him up. Thanks again...I'll keep a post going with updates. You at least saved me $60-$100 on getting a switch I didn't need, so I owe ya!:thumbsup:

BTW, when is the last time the fluid was changed in the transfer case? It should be changed every 50000 miles, and the only fluid for this is from GM (Autotrak).
 

therealfleen

Original poster
Member
Mar 3, 2014
12
MAY03LT said:
Did you try flicking the switch with the meter hooked up? The ohms at rest are usually what goes bonkers when the switch fails.



Not a typo, they are correct.:cool:

linneje nailed it. A scan of the TCCM might be next best step. If your local to me hit me up.

Thanks! I wish I were closer....MI here. Thanks for the PM....Looks like I will head to get er scanned. And the fluid has about 35,000 on it.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
linneje said:
BTW, when is the last time the fluid was changed in the transfer case? It should be changed every 50000 miles, and the only fluid for this is from GM (Autotrak).
Is this true also in the Suburban we're discussing here?
 

linneje

Member
Apr 26, 2012
404
The_Roadie said:
Is this true also in the Suburban we're discussing here?

I was aware that it was a suburban, and it is the same service interval. As far as I know Autotrak II is the only fluid they produce for the Transfer Case on these 4WD platforms.
 

IllogicTC

Member
Dec 30, 2013
3,452
The_Roadie said:
Is this true also in the Suburban we're discussing here?

Yes. There's a bunch of NVG cases that do A4WD, and take Auto Trac II, the reason being they're also cursed with the clutch packs. :rotfl: Big'uns with their NVG 246, our 226, the AWD folks with their 126...

The first digit is the number of speeds the transfer case has.

The second is a rating of strength (from 1 to 7, the Suburbans and whatnot get a 4 and we got a 2 :rotfl:)

The third digit is the type. Anything ending with 6 is a wet clutch system.

Also of note, GM owned a 36% share of NVG which was sold to DaimlerChrysler (the owner of the remaining shares) in 2002, before another company bought 80% in 2004 and the remaining 20% in 2007. So, we're running sorta-kinda-maybe Mopar transfer cases :rotfl:
 

therealfleen

Original poster
Member
Mar 3, 2014
12
Update: codes indicated the encoder motor underneath. Swapped that - all is well!:wootwoot:
Thanks for all the help everyone!
 

linneje

Member
Apr 26, 2012
404
That is great! Kudos to yourself for undertaking the troubleshooting to get to the bottom of it. Happy trails!
 

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