Awful time trying to figure out WHAT is wrong with 4x4 on '99 Suburban...

[OverRunWithSons]

I am the wife doing this thread...to help husband.. and basically his Mechanic to figure this out... about 180,000 miles.. gets STUCK in 4x4... husband can't get it out.. takes to mechanic , (afraid of breaking bolts in transfer case) ... then Mechanic gets it stuck in neutral... it's been in the shop for over a month now.. we just need our truck back before winter !@#$%

1. Bought new 4x4 switches ($40) ... not that..

2. Bought new Transfer case Motor after the one from the Junk yard didn't work.. still not the culprit.. ($75 used plus $150 new)...

3. Now facing buying "Transfer Case Control Module"...

Don't know if we need this one...

A) Dorman - Renew Remanufactured Transfer Case Control Module Part No. 599-104 (1999 Chevrolet K1500 :Active; Push Button Shift (NP8)


OR

B) Dorman - Renew Remanufactured Transfer Case Control Module Part No. 599-108 (1999 Chevrolet K1500 -Electronic Shift (NP1)

What else can go wrong with this Four wheel drive? Please be detailed ! .. at this rate.. we're ready to let it drive over a hill !


These are the #'s on the Transfer case -how can we figure this out ?

246 GM
1503 73754
11 13 98 K1
272

[95 S_Trucker]

NP1, 2 speed transfer case, electronic shift.

If you have NP1, you will have 3 buttons on your 4wd switch, and RPO NP1 listed in the glove box. You would have a NP243 transfer case.


NP8, 2 speed transfer case, active shift

If you have NP8, you will have 4 buttons on your 4wd switch, and RPO NP8 listed in the glove box. You would have a NP246 transfer case.



The big difference between the two is on will have the auto 4wd feature and the other wont. The modules are not interchangeable.


The clutches could be burnt up in the Np246 transfer case, causing 4wd not to work. "pump rub" is a problem that will destroy a 246 transfer case.


Does the encoder motor move? do the buttons light up on the 4wd switch?

[OverRunWithSons]

Originally Posted by 95 S_Trucker

The clutches could be burnt up in the Np246 transfer case, causing 4wd not to work. "pump rub" is a problem that will destroy a 246 transfer case.


Does the encoder motor move? do the buttons light up on the 4wd switch?

To answer these last 2 questions.. husband said "NO" to both...

Thank you very much for this info -explaining the differences...

This '99 has the Auto 4WD option = 4 buttons on the switch...


This one >> Dorman - OE Solutions Four Wheel Drive Selector Switch - Part No. 901-130 - 1999 Chevrolet K1500 Suburban LT Transfer Case (NP8)

Oh I guess that is our answer then.. we need the NP8!!

The Mechanic we go to is a older guy.. not BIG repairs, if a transmission or motor blows.. we'd have to go somewhere else.. we were hoping to find which is the correct module, bringing it to him before he tears it out of there.. so I guess the answer is A .. even without looking at the Glove box..

[OverRunWithSons]

Originally Posted by 95 S_Trucker

The big difference between the two is on will have the auto 4wd feature and the other wont. The modules are not interchangeable.


The clutches could be burnt up in the Np246 transfer case, causing 4wd not to work. "pump rub" is a problem that will destroy a 246 transfer case.

We have a '97 Suburban which has the NP1 (3 buttons).. never had issues.. it sounds these NP8's are more trouble than they are worth, given what you said here.. how to avoid these issues ??

When husband was in the shop today... Mechanic was telling him another Mechanic down the road had some guy bring in a truck with the SAME ISSUES as we are having.. replacing this & that.. and still couldn't get it figured out.. they ended up telling the guy to come get it.. we're hoping this doesn't happen to us !

Husband was wondering if all else fails ... can we DOWNGRADE to the same transfer case that the '97 has (NP1), transfer case MOTOR, the 3 position switch & transfer case control module ?? or maybe there is more !

[95 S_Trucker]

First, check fuse#24 in the I/P fuse box. Its a 20A fuse.

It will be a lot of work changing to a 243 or a 241 transfer case. It is possible, but if your mechanic cannot figure out what's wrong now, he will not be able to deal with the wiring changes that are needed when swapping transfer cases.

[95 S_Trucker]

You should be able to see codes and live data, and possibly do some bi-directional controls through the transfer case module with a scan tool. You will need a decent one, not just a code reader. Your mechanic should have one.

I know for sure the solus pro and modis ultra will do it. They are both snap on. That's what I use here at my shop. But I'm sure there are some others that will work too.

[OverRunWithSons]

Ok.. here is where we are.... basically no where ...replaced new switch... ...then bought new Transfer case Motor (Wondering now if we bought the wrong one ...see below)..

Last thing bought new was the "Transfer Case Control Module" here >> Dorman - Renew Remanufactured Transfer Case Control Module it says : Active; Push Button Shift (NP8) ..

...... now the only thing happening is the Neutral light is ON.... ..Husband just brought the Burb home.... still a project...

The Mechanic is an older guy about ready to retire.. he doesn't have all these testers.. we brought this tester.. ScanTool 425801 OBDLink SX USB: OBD......(yeah cheap I know!)... husband hooked this up today with the laptop at the shop....NO CODES at all....

Mechanic was concerned this Transfer case Module was WRONG.. as this is what was taken out..... ..and here I am thinking...after comparing motors back on advance auto.. just maybe we bought THE WRONG MOTOR ??? (Modules, Motors, this gets confusing !)

Was looking up the Transfer case Modules on Ebay.. seen many with different numbers...most for sale start out with the "157" like this one...


but ours was a "15009564" (above picture).. what is the difference with these numbers ??


We bought this.... Cardone Transfer Case Motor - Remanufactured - (Price $179) fits "1999 Chevrolet K1500 Suburban LT
Reman. A-1 CARDONE Transfer Case Motor; 4WD; with 4 Terminal Harness Plug; with 6 Terminal Plugs" - (no where does it mention NP8).. I think we bought this BEFORE I did this thread even.. so we didn't know what we were doing.. thought they were the same product.. just different manufacturers ??

Is this our blunder.. is THIS the Transfer case motor we should have bought -This one is called a "Shift motor"..

Dorman - OE Solutions Transfer Case Shift Motor ... (price $235) fits 1999 Chevrolet K1500 Suburban LT..Fits New Venture Gear 136/236/246; RPO Code NP8; 4 Pins

Thanks guys!

[OverRunWithSons]

Another question.. I read THIS review about the Cardone Motor on Amazon just now.....

Cardone 48-105 Remanufactured Transfer Case Motor


The reviewer says : "It works, but you still have to have the computer reset at the dealer to get it to function if you replace it yourself... 2000 ZR2 Blazer"...

Is this our problem.. our mechanic is not a Dealer... we need to have something reset at a shop who does this ??

Looking at these 4 options for the 1999 Suburban 4x4 side by side on Oreily's site.. is there any difference between #1 and #3 ?? Both should work in our Burb.. shouldn't they ?

Dorman and Cardone Transfer case motors

[OverRunWithSons]

I just called a Cardone Tech, he assured me that their product is the SAME as the Dorman OE Solutions - Transfer Case Motor so that rules all my questioning to rest...

He also said nothing needs to be "set" on this motor...and husband read nothing needs to be set on the Module either...it says "plug & play for easy economical installation -no programming required"....

Back to square one! .. is it possible the Inside of the transfer case needs rebuilt ? except husband says..."even with the motor not connected onto the side of the transfer case, it will not work... he added.. "they had it grounded" too.....

Ideas anyone ??

[95 S_Trucker]

The control module for NP1 will only have 1 electrical connector.

The NP8(what you have) will have 2.

The shift motor for the NP1 will have 2 connectors, one 6 pin connector, and one 2 pin

The shift motor for the NP8 will also have 2 connectors, one is a 6 pin, and the other is 4pin.

The shift motors and control modules are not interchangeable between the two systems. The wiring is different. You cant physically plug the wiring connections together. Its impossible to mix up the parts.

Both the shift motors you posted will fit NP8. One is new and one is remanufactured.

The scan tool/cable you got is for ECM/PCM codes and data only. It will not look at any other module(like abs, air bag, and transfer case)

I would look locally and think about taking it to another shop. Your mechanic replaced everything instead of diagnosing the problem.

[K20rookie]

I had a similar problem on my 05 silverado and chased it for weeks. It ended up being a loose connector on the transfer case. The clip had broken off and the plug wasn't making full contact. Sounds simple, but might be worth checking if that hasn't been done already.