02 Tahoe Service 4WD fixed!

[gspost12]

Following the advice in this forum, after my service 4wd message came on, I replaced my dash switch and transfercase actuator motor. My tahoe would go into 4wd hi, but not back to 2 wheel drive. I could hear the motor trying, but it would never move back. I replaced the transfer case oil with synthetic, worked the lever with a wrench til it switched gears easily, and put everthing back together. Worked for 24 hrs and same message. Another actuator motor and same result. Finally, took it to a local mechanic I trusted. He replaced the same motor and it still didn't work. At this point, both he and I thought electrical. He pulled resistance on each wire and found 1 that was broken. Ran a single wire to bypass this and I now have control of the transfer case again. Just wanted everyone to consider this as a possible problem when chasing what is causing your service 4wd message.

[j cAT]

Originally Posted by gspost12

Following the advice in this forum, after my service 4wd message came on, I replaced my dash switch and transfercase actuator motor. My tahoe would go into 4wd hi, but not back to 2 wheel drive. I could hear the motor trying, but it would never move back. I replaced the transfer case oil with synthetic, worked the lever with a wrench til it switched gears easily, and put everthing back together. Worked for 24 hrs and same message. Another actuator motor and same result. Finally, took it to a local mechanic I trusted. He replaced the same motor and it still didn't work. At this point, both he and I thought electrical. He pulled resistance on each wire and found 1 that was broken. Ran a single wire to bypass this and I now have control of the transfer case again. Just wanted everyone to consider this as a possible problem when chasing what is causing your service 4wd message.

some have had wiring issues. damaged caused by rodents or careless mechanics working on the vehicle....

what fluid did you use for the transfercase ? Trac II ?

[gspost12]

You are correct. I used GM Auto Trak II fluid. Mis-spoke when I said I had replaced it with synthetic. The old fluid was pretty dark (110K on vehicle) compared to the nice color of the new fluid. I saw no evidence of damage to the wiring nor did the mechanic. Service 4WD happened out of the blue. Something may have been thrown up there and caused damage, but it was not evident.

[j cAT]

Originally Posted by gspost12

You are correct. I used GM Auto Trak II fluid. Mis-spoke when I said I had replaced it with synthetic. The old fluid was pretty dark (110K on vehicle) compared to the nice color of the new fluid. I saw no evidence of damage to the wiring nor did the mechanic. Service 4WD happened out of the blue. Something may have been thrown up there and caused damage, but it was not evident.

depends on how you use your vehicle , when these drive train fluids are to be replaced. I find 30 -40,000mi the fluid gets off color. thats when I replace it..

I always notice that with new fluid it does go into 4wd faster/ usually two light flashes.