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Username Post: 4x4 Code C0306        (Topic#365578)
400sbplow 
Newbie
Posts: 36

Reg: 01-04-10
06-21-21 03:59 PM - Post#2821917    

So I just got done with this.

I got a 'Service 4WD' message on the cluster and it wouldn't pushbutton shift out of 2WD, the light for 4WD would blink, I could hear it trying to shift and then it would give up and stay in 2WD. After a couple of weeks and several tries it would shift once in a while but not reliably. And I stopped messing with it because I didn't want to be stuck in 4WD

I had read that the most common issue is a bad ground on the body mount just under the driver's door. I took it apart and cleaned it up but it didn't look that bad and didn't change anything.

I located the TCCM (transfer case control module under the dash above the parking brake, a little computer box a bit bigger than a deck of cards. There's three plugs on it, two have a bunch of small control wires and one with four 10 gauge power wires (black, orange, black, red) that's what I was after.

I tested the ground & power (black & orange) with a 60 watt bulb and monitored voltage on the circuits under load, they were fine. The motor A & B leads had about 3.6 ohms from lead to lead (black & red) and no continuity to ground so all the wiring looked okay.

Since everything else looked and functioned okay I took a chance and bought a shifter motor. I watched some videos of it being changed, it was easy enough. I didn't pull the front driveshaft as many had recommended and the middle mounting bolt of the three was a pain with the U-joint in the way but it wasn't terrible either. That bolt came out with the shifter assembly and went back in with it and required some patience getting one click at a time with a 12 point box end wrench.

Only other trick was that once the old shifter was off I had to shift the transfer case into neutral to get the new shift motor on. That's the position it comes in and you don't want to move or force it while it's not on the transfer case. Make sure you get the one special bump in the splines lined up right.

I got the whole mess back together, turned the key on and...nothing. It wouldn't shift the transfer case out of neutral, I was about to start a string of profanity but then remembered to put the transmission in neutral first, then the transfer case shifted fine, crisis averted. I tested all functions on my dirt driveway where you can easily tell if it's in 2 or 4 and it's all working right.

Looking at the old shifter it was obvious that it had gotten some water inside over time and swelled up to where the mechanism had jammed.

There's a steel locator tube on the top mounting bolt hole, I was able to break the aluminum tab off the old shifter and get it out and swapped into the new one. There's also a plastic gasket piece that I could have bought new but the old one was fine after I cleaned all the aluminum salt off it.

I'll revisit this if the Dorman shifter I bought (about $300, not cheap) fails in the near future. That's all for now. I'm glad it failed in the summertime.



 
wagonman100 
Site Ambassador
Posts: 15238

Loc: Baltimore, MD
Reg: 11-27-04
06-25-21 02:00 PM - Post#2822093    
    In response to 400sbplow

Sounds like you solved it. I replace my encoder motor a couple of years ago. I put it in, hit the button and it went into 4wd. So I thought nothing of it. The next day I tried it again and it wouldn’t go into 4wd. I had a replacement dash switch in my console, so I popped the old one out, plugged in the new one and everything worked fine again.

Jay
Friends don’t let friends drive Fords.

1999 Silverado Z71 4X4 extra-cab short bed
1983 Malibu Fauxmad - tubbed
1978 El Camino Kustomized
1972 Monte Carlo
1957 210 handyman wagon
1957 Nomad sport wagon
1957 Cameo Carrier


 
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