Transfer Case/ trans issue

[BowtieMafia66701]

Hey guys,

I just got a 2003 tahoe LT 4x4. I have a few questions i am trying to figure out. When i got it the guy said he put a used transmission in and he wasnt sure if it has the right transfer case or not. So i am curious how i can find out what transfer case goes in it i want to make sure its the right one because i know its gonna need some trans work i am assuming.


Secondly, i need some advice hooked up my code reader because when i am driving it dosent seem right. It runs well but i am not seeing or feeling any shifting. I think its in 3rd or 4th gear. But i got a few codes which tells me its gonna need work. Ive attached most of the codes i got. I am wondering if its worth it to replace the parts its saying is wrong or go ahead with a rebuild or take it to a shop and have the whole thing replaced. Which is why i am trying to find out what transfer case is supposed to go on it. Any help or advice would be greatly appreciated.

 

[Fless]

Do you have the 2-speed switch on the dash? It would have AUTO, 2HI, 4HI, and 4LO buttons. If so, that's the NP246 case. You can also crawl under and look for the tag on the case:

If your dash switch is different, post up a pic of it, or of your full RPO code sticker that's inside the glovebox lid.

 

[BowtieMafia66701]

This is my switch. Only why i am asking is he said he put another transfer case on it but he wasnt sure it was the right one and there was a few different ones.

 

[Fless]

See if there is a tag on the transfer case; also look at your RPO codes and look for an NP8 code. If it's not there, post up the other "Nxx" codes and we can tell you what it came with originally.

Do you know if that dash switch was changed? The earlier models had the gray buttons (yours looks gray to me), but the 2003-2006 models had black buttons, and they're different switches based on part numbers. But I'm not sure how they're functionally different.

 

[BowtieMafia66701]

It does have the np8 code. The dash i am sure has been out thats another issue i have to fix is they put a escalade cluster in and nothing works on it. So i know the dash has been apart but i dont know if they changed the buttons or not. I am gonna assume they did.

 

[NickTransmissions]

Hey guys,

I just got a 2003 tahoe LT 4x4. I have a few questions i am trying to figure out. When i got it the guy said he put a used transmission in and he wasnt sure if it has the right transfer case or not. So i am curious how i can find out what transfer case goes in it i want to make sure its the right one because i know its gonna need some trans work i am assuming.


Secondly, i need some advice hooked up my code reader because when i am driving it dosent seem right. It runs well but i am not seeing or feeling any shifting. I think its in 3rd or 4th gear. But i got a few codes which tells me its gonna need work. Ive attached most of the codes i got. I am wondering if its worth it to replace the parts its saying is wrong or go ahead with a rebuild or take it to a shop and have the whole thing replaced. Which is why i am trying to find out what transfer case is supposed to go on it. Any help or advice would be greatly appreciated.

You're trans is in limp mode (has nothing to do w/the Tcase which if you have the np246 installed (RPO code = NP8) is correct for your vehicle. If you had an issue with the tcase (electrical, anyway), you'd throw a chassis/tcase code and that's usually encoder motor sensor or the motor itself is bad.

When I see that many codes on one vehicle for the transmission, my first suspection is an electrical short to ground somewhere, either internally inside the trans (perhaps bad harness) or externally.

Check external grounds then make sure you're at least getting 12v to the trans. If everything looks/checks good on the outside, drop the pan and start ohm'ing out all your solenoids. The two shift solenoids (A & B) + the 3-2 solenoid should all read between 20-22 ohms; the PWM solenoid should read 9-11 ohms and the electronic pressure control solenoid should read 4.5-6 ohms. If they all check ok, id replace the harness and pressure switch manifold assembly and see if that fixes the problem.

 

[BowtieMafia66701]

You're trans is in limp mode (has nothing to do w/the Tcase which if you have the np246 installed (RPO code = NP8) is correct for your vehicle. If you had an issue with the tcase (electrical, anyway), you'd throw a chassis/tcase code and that's usually encoder motor sensor or the motor itself is bad.

When I see that many codes on one vehicle for the transmission, my first suspection is an electrical short to ground somewhere, either internally inside the trans (perhaps bad harness) or externally.

Check external grounds then make sure you're at least getting 12v to the trans. If everything looks/checks good on the outside, drop the pan and start ohm'ing out all your solenoids. The two shift solenoids (A & B) + the 3-2 solenoid should all read between 20-22 ohms; the PWM solenoid should read 9-11 ohms and the electronic pressure control solenoid should read 4.5-6 ohms. If they all check ok, id replace the harness and pressure switch manifold assembly and see if that fixes the problem.

Thank you very much for the information. Greatly appreciated. Only reason i asked about the tcase is the guy who i got it from didnt know if it was the right one. So i am gonna slide underneath and check it out on my day off. I tried engaging 4 wheel drive but it did nothing. So i wonder if the limp mode could cause this or it is the wrong transfer case. Just wanting to make sure everything is right before i start getting it all fixed. But again thank you again for the info

 

[Fless]

You will need a more advanced scanner to be able to read the 4x4 codes, if there are any. If you have a DIC (Driver Information Center) are there any messages on it? Maybe not with that cluster being dead.

 

[NickTransmissions]

Thank you very much for the information. Greatly appreciated. Only reason i asked about the tcase is the guy who i got it from didnt know if it was the right one. So i am gonna slide underneath and check it out on my day off. I tried engaging 4 wheel drive but it did nothing. So i wonder if the limp mode could cause this or it is the wrong transfer case. Just wanting to make sure everything is right before i start getting it all fixed. But again thank you again for the info

You're welcome, man.

Let us know what t-case you have but your transmission limp mode itself is an entirely separate issue and by itself would not cause your lack of 4WD functionality (im assuming you're in neutral and stopped when trying to shift into 4WD). However shorts or other electrical problems upstream of your trans/tcase can be causing both the trans and tcase command/control problems you're having.

All that said, im not sure an incorrect tcase would even install in place of the correct NP246 (others can confirm or deny).

You can use most any Snap On scan tool, Autel as well as the more advanced OTC/SPX brand scanners to read chassis codes.

 

[Fless]

If it's the NP246 t-case (almost guaranteed) you can switch between AUTO, 2HI, and 4HI modes on the fly. For going in and out of 4LO you need to be in neutral, at a standstill or rolling slow, less than 3mph. Download a copy of your owner's manual from GM's website for the skinny.