Service 4wd error
 

Hi. I got the service 4wd message on a 2005 h2, I read up on it and since i have another h2 i could take out the parts to test on the one with the error, I ended up replacing buttons on the dash, replaced transfer case control module under the steering wheel, and transfer case motor and I'm still not getting it to work properly.

At first it showed the error on the cluster and the motor didn't move... after taking parts out and parts in it ended up looking like it was solved because the transfer case motor was out of the transfer case and i could see it move to change the gears like it should. Shifted it around 20 times before putting it in place and it suddenly stopped moving, error came up on the cluster again... started replacing parts again, checked TREC fuse in the engine compartment and 4x4 fuse in the dash, fuses are OK. After messing around some more and changing the parts back and forth (buttons, module and motor), right now it's not showing the "service 4wd" on the cluster but it doesn't change gears, it just blinks until it quits and goes back to the one it was previously.

Any other solutions I should try?

I would take off the encoder motor and try to manually switch your transfer case into its functions and if it doesn’t move manually, then it’s your transfer case itself. And that just going on what you said in your post.

On the description I made in my above post the motor is already out, we are making the test with the motor already out of the transfer case

do all the "new" truck parts work on the "old" truck? if so then it is probably a wiring issue on the "new" truck. also make sure the encoder motor is in the same position as the transfer case.

I stopped/refused installing customer's used parts over 20yrs ago. I have been sleeping better at night since!
Diagnose the source, then get a replacement.

My H2 is in the same issue Service 4wd I took out the motor took it apart (motor part) cleaned and reassembled plugged it in without mounting it and it cycles fine through all the settings. Can’t say the same for the transfer case and we’ll mine makes a clicking sound if I lay into the the gas hard pretty sure I need to rebuild it. Point is it seems hard to manually shift it meaning quite hard for a motor to do it. So I have to plan on taking it out for rebuild then possibly a new actuator motor. Since you have two h2’s compare manually shifting them?

Someone told me you get this error periodically so run through all the transmission selections every once in a while.

I used to get this on my 05, since doing this the issue has never occured again (touch wood) anyway its easy to try

Found the problem, broken wire under the gear shifter, sometimes it made connection and the car knew it was in Neutral and the motor worked, other times the wire would stop making a connection and the car didn't know it was in neutral so it gave errors or simply wouldnt change gears.

i am glad you found the issue.

Ditto