the 4 wheel drive quit working on my wifes 02 trailblazer when you turn the knob to put it in 4 wheel drive it just blinks and on the dash it lights up service 4 wheel drive, any ideas ? anybody else had this trouble ? 54,000 miles
Dude! The 4x4 system has it's own computer. You can access it with a scan tool.
Code "1" is "RAM standby power" and is considered normal, may be caused by clearing the codes.
Code "2" is "Encoder fault"
Code "3" is "TCCM motor circuit"
Code "4" is "RAM/ROM failure"
The TCCM is the transfer case control module. It's located where our Buicks ECMs are located. Sometimes unpluging them and plug it back in works only temporary.
There are a lot of things that cause that particular symptom.
cracked/disconnected vacuum line
vacuum switch (mounted on firewall)
transfer case encoder motor
front diff posi lock actuator
It's unreal the amount of things can go wrong on these blazers.
Best bet is to get a scanner and start there.
Good Luck.
