1999 w/4 button 4x4, doesnt work

[96_blazer_5spd]

ok so i have a 99 that i have replaced the encoder motor on, and the dash switch and still nothin happening to engage 4x4, fuses are good, power running to switch, the back illumination lights are on but it only has gear selection lights sporadically and then only 4wd auto. any ideas?

[travis00]

Its 1 of 4 problems
1 encoder
2 switch
3 tccm
4 wiring
You already changed out 1&2. The tccm (transfer case control module) is behind the pass. side kick panel.Do u ever hear any relays clicking from the tccm? Also check the connector going to the tccm. I've heard of wires pulling out of the connector.
Is the service 4x4 light on?
I'm having problems with my 99 as well. Sometimes i get no lights on the switch sometimes I get all the lights. I was told you can ground pin 13 of the OBD2 connector and get a code, but there is no pin 13 on my connector.
Took mine to autozone to read codes and service 4x4 and ABS codes cann't be read with a hand held scanner. Has to go to dealer to read codes.
Let me know what you find
T

[MT-2500]

Originally Posted by 96_blazer_5spd

ok so i have a 99 that i have replaced the encoder motor on, and the dash switch and still nothin happening to engage 4x4, fuses are good, power running to switch, the back illumination lights are on but it only has gear selection lights sporadically and then only 4wd auto. any ideas?

You need to get it on a good transfer case/transmission /engine capable scanner to get to the problem.
Usually there is some test in the scanner and codes to point you in the right direction.
If you can get codes post back code no.
MT

[laxman21]

Have you checked the vacuum valve/switch on the fire wall?


It's right in the middle above the distributor.

[96_blazer_5spd]

sorry for the late replies, i havent been able to get it on a scanner yet, and travis if you have switch with the 4wd auto button, it is a 236 transfer case and can only be read with a scanner, the 233 can be grounded for the codes