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95 S_Trucker · 09-08-2015, 05:07 PM

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?

09-08-2015, 05:07 PM	#2
95 S_Trucker Registered User Join Date: Oct 2009 Location: . Posts: 2,179	Re: Awful time trying to figure out WHAT is wrong with 4x4 on '99 Suburban... 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?