2002 tahoe z71 Service 4wd light on, no blown fuses, new selector switch.

[Ialsofkdyourdad]

https://www.amazon.ca/Transfer-1238...17208442&psc=1&ref_=d6k_applink_bb_dls_failed




Is that the encoder I would need? They list it works on a bunch of dodge vehicles as well so I want to be sure

 

[Doubeleive]

Yea it drives perfect. I'll see if everything is connected, I just ordered a scanner so I can use the app scottydogs suggested, should be at my house on Tuesday so if it's not a faulty ground or unplugged harness Ill give it a scan.


I'll look into an encoder motor now but I just bought the truck a week ago so if it's expensive I may have to put fixing 4wd on the backburner

Better to try and troubleshoot it a bit before just dropping money on parts, the encoder motor is common but it could still be something else, if you bought the dorman switch those things get a bad rap all the time too.

 

[Scottydoggs]

That app will read the tccm? Everything I have been reading has said only a tech 2 can read it. I can take it to a chevy dealer but if I could scan it myself with a Bluetooth module I'd prefer that lol

yes it will, srs, abs all that stuff. even shows abs history codes and you can clear them codes.

 

[Doubeleive]

https://www.amazon.ca/Transfer-1238...17208442&psc=1&ref_=d6k_applink_bb_dls_failed




Is that the encoder I would need? They list it works on a bunch of dodge vehicles as well so I want to be sure

that one looks like it is for 03 and up, yours will be 01-02, beware of parts showing 99-00 they made a change in 00 and 1/2 were one design and 1/2 were another. then they made a change again in 03

 

[Ialsofkdyourdad]

that one looks like it is for 03 and up, yours will be 01-02, beware of parts showing 99-00 they made a change in 00 and 1/2 were one design and 1/2 were another. then they made a change again in 03

OK I'll make sure I find the right one then

 

[Ialsofkdyourdad]

yes it will, srs, abs all that stuff. even shows abs history codes and you can clear them codes.

OK cool my Bluetooth obd thing is ordered so I should have that soon

 

[Fless]

Definitely recommend getting the 4x4 codes before doing anything. There are myriad issues that can cause the Service 4x4 message.

If you do get to the point of changing the encoder motor on the transfer case, be sure to check which motor you need by removing the old one before ordering. Some mate with a splined shaft and others mate with a shaft with two flats. Yours is about the year that the transition was made.

 

[mdmcinti]

Here is a good video that may help you pin point the issue. It is related to the ground. It seems like anything electrical in my experience on these trucks alway seem to be the grounds.

 

[Fless]

There are multiple threads on this. Here's one that has some other threads linked in Post #6:

https://www.tahoeyukonforum.com/threads/“service-4wd”-message.119576/

 

[swathdiver]

Good question @swathdiver got any documentation on the volts/ohms?

Not for his and if the same for the 900s, I tried but cannot find them in my present condition. AllDataDIY for access to the shop manual online.