“Service Four Wheel Drive”

[Bill Barnes]

Venting: It’s important for my use the transfer case Neutral position functions, because I bought this truck to tow behind our motorhome.

I tested it before I bought it in December.

I have operated it a few times since.

Today I hook it to the tow bar for a test run and when I put the selector to N I get “Service four wheel drive system”.

Leave it sit for five minutes and the message disappears. Everything works; 2H, Auto, 4H, 4L. Except when I try neutral again and the error message pops up. Rinse and repeat several times, same thing every time.

So, back in the garage. I’ll check the connectors in case the dealer left something loose when they replaced the transmission recently. No, the connectors look good, they even put dielectric grease in them. So, I cleaned out the plugs and sockets with contact cleaner, just in case there’s some grit or foreign material held by the grease that may inhibit a good contact. Aaaaand success! In and out of every position including neutral, just like clockwork. Repeatedly.

Back to the tow bar I go. Hook up the bars and all the umbilicals. Shift into neutral. “Service four wheel drive system”.

It sounds as if the encoder inside the transfer case Motor is having an issue. I replaced the motor at 120K rather than take it apart and replace the encoder, because the seal has to be intact to protect the encoder. Now at 200K I'm having intermittent "SERVICE 4WD" message on the DIC. I'm going to replace the t-case motor again.

 

[Fless]

It sounds as if the encoder inside the transfer case Motor is having an issue. I replaced the motor at 120K rather than take it apart and replace the encoder, because the seal has to be intact to protect the encoder. Now at 200K I'm having intermittent "SERVICE 4WD" message on the DIC. I'm going to replace the t-case motor again.

Have you had the codes read? If so, what code is setting the message?

A Tech 2 would help immensely to troubleshoot.

 

[Bill 1960]

Just to wrap this up, it’s 2 months later and a few thousand miles of towing and the problem seems to have resolved. Perhaps in part due to exercising the shift mechanism through the full range of functions? Neutral probably never got used until I got it.

Or perhaps after I resigned myself to shifting in and out of neutral with the engine running and trans in neutral. That’s what it likes.
I prefer to shift out of neutral with the engine off to avoid gear clash when the spinning ones meet the stationary ones. I’ve practiced that with many vehicles. But the Hoe does not like it.