"Service 4wd" message came on briefly - something to worry about?

[1stDeuce]

If it's doing shifts on it's own, or nothing at all happens when you push the switch, then suspect that the switch is going bad and needs replacing.

The front axle solenoid usually just stops working, and you'll get a service 4wd message that never goes away, or comes on in a specific mode, when the monitor circuit shows it's not moving to the correct position for that mode. IME, it's not terribly common for that solenoid to have issues on newer trucks with the screw-drive solenoid. (~'97-up IIRC)

If it's the encoder in the shift motor, it'll randomly spit out the Service 4wd message, and you might hear it "hunting" around for the proper position as the message comes up. It'll usually re-try and succeed, but the message stays up till you re-key. Since the problem is from lack of use, using it even less because you're afraid it won't work just means it'll totally fail on you sooner.

My suggestion is to do the opposite... USE the system a bunch TODAY and see what happens. Shift it through all ranges about 20 times. If it sets the code, put it back in 2wd if it'll go, re-key to clear the code if possible, and do it again. If you have a problem, NOW is the time to find it, not while you're on a trip. If it doesn't have any more issues, then use probably cleaned the contacts up. It'll be fine and you can stop worrying, so long as you keep shifting through all modes occasionally.

Good Luck!

 

[1stDeuce]

Hmm, as I suspect your issue is the encoder, here's an alternative to putting in a whole new shift motor... It appears you can replace just the encoder section. It doesn't look terribly rebuildable, so this might be a good option if it gives you any issues when you exercise it later today.

http://www.dormanproducts.com/itemdetail.aspx?ProductID=45401&SEName=600-120

 

[snowblind]

Hmm, as I suspect your issue is the encoder, here's an alternative to putting in a whole new shift motor... It appears you can replace just the encoder section. It doesn't look terribly rebuildable, so this might be a good option if it gives you any issues when you exercise it later today.

http://www.dormanproducts.com/itemdetail.aspx?ProductID=45401&SEName=600-120

I'm on my second Dorman encoder motor. My stock one lasted 90k miles, The first Dorman only lasted 11 months. If this next one doesn't last longer I'll pay the $$ for a new stock one.


Matt

 

[Rorywg]

I am having a similar problem on my 2012 Raptor. Not to hijack the thread, but does anyone know if the Ford setup is similar?

 

[kojackJKU]

My rig was having shifting issues etc with the buttons. After I replaced the front solenoid it went back to normal. You can "test" if one of the solenoids are bad by doing the sound test. have someone shift your rig into 4wd/2wd 4wd lo and so on, if you hear the transfer case shifting, then you know that its most likely the front solenoid giving you fits. if it does not shift in the transfer case, then its either the encoder on the transfer case or your switches. but that's a free starting point there.

 

[gtbensley]

Bit different, believe it uses a vacuum system to lock the hubs (actually the vacuum keeps them unlocked) as well as an encoded motor on the transfer case.

 

[rayra]

Seems most of the anecdotes and vids I can find are resolved with changing the dash switch module. For $40-50 and the age of the vehicle, and an impending road trip, were it me I'd spend the money and change it right now. Seems to be one of those GMT800 design bugs where if it hasn't failed yet, it's going to anyway. 'Preventative maintenance' makes it an easy choice for me. Rather spend the money now than wind up stuck in 4Lo on a road trip, or unable to get in 4wd when I need it.

Seconding the idea of getting your ear up near the transfer case and front axle solenoid while someone else cycles thru settings on the switch. But if the trouble is intermittent that won't be definitive anyway.

 

[kojackJKU]

Fixed mine rayra....my switching was acting all wonky, never got the service 4wd notification once.

 

[Martinjmpr]

If it's doing shifts on it's own, or nothing at all happens when you push the switch, then suspect that the switch is going bad and needs replacing.

The front axle solenoid usually just stops working, and you'll get a service 4wd message that never goes away, or comes on in a specific mode, when the monitor circuit shows it's not moving to the correct position for that mode. IME, it's not terribly common for that solenoid to have issues on newer trucks with the screw-drive solenoid. (~'97-up IIRC)

If it's the encoder in the shift motor, it'll randomly spit out the Service 4wd message, and you might hear it "hunting" around for the proper position as the message comes up. It'll usually re-try and succeed, but the message stays up till you re-key. Since the problem is from lack of use, using it even less because you're afraid it won't work just means it'll totally fail on you sooner.

My suggestion is to do the opposite... USE the system a bunch TODAY and see what happens. Shift it through all ranges about 20 times. If it sets the code, put it back in 2wd if it'll go, re-key to clear the code if possible, and do it again. If you have a problem, NOW is the time to find it, not while you're on a trip. If it doesn't have any more issues, then use probably cleaned the contacts up. It'll be fine and you can stop worrying, so long as you keep shifting through all modes occasionally.

Good Luck!

.
OK, just got back from our camping trip and I have some more data to add:
.
On Saturday we took a group of people out to the Sand Wash Basin in Northwestern CO to look for wild horses. Last year when we went out to the same area, it had recently rained and it was a muddy mess requiring us to be in 4wd a lot. This year it was pretty dry so we were all in 2wd.
.
At one point, we turned off the main road and onto a two track on soft soil. Just to be safe I switched to 4 hi, no issues. We explored that a short distance until it dead ended and then we turned around. Upon returning to the main road, I switched back to 2hi - and got the "Service 4wd" message. I cleared the code but as we were driving along slowly on a dirt road, I thought I'd "exercise" the system - but found out that it would not switch out of 2hi. Then we stopped for lunch and shut the vehicles off. When we started again, I pushed the button to shift to 4hi and it went into 4hi with no issues at all. However, when I switched it back to 2hi, I again got the "Service 4wd" message.
.
We didn't need 4wd for the next couple of days so I left it in 2hi. Then, on Tuesday a different group of us went out to see some petroglyphs on a very remote road (Vermillion Canyon, if you're familiar with the area. ) The road was on very soft dirt and very steep. I switched to 4hi for most of the 8 mile drive down and most of the way back - no issues and no warning messages. Near the bottom of a particularly steep hill, I actually switched it to 4lo. It went into 4lo with no issues and I was able to power right up to the top of the hill. When I got to the main road again, I switched back to 2hi with no problems and no warning messages. It hasn't given me the "Service 4wd" message since last Saturday.
.
From all the symptoms I'm seeing, I think 1st Deuce has it right - the problem is not the switch, it's the encoder motor and seems to be arising from lack of use. The more I used 4wd the fewer issues I had.
.
Now my only dilemma is whether to try to fix it myself or not. I did watch a YouTube video of an encoder motor replacement - it doesn't look terribly hard. For those who have done it, how difficult would you say it is?
.
As far as just replacing the ring goes, from what I've seen I'd still have to pull the entire encoder motor out anyway, right? My thought is that if I'm going to pull the whole thing out, I might as well replace the whole thing unless there is a huge cost difference. IIRC the entire encodor motor is a ~$200 part, right? Honestly I'd pay $200 if it meant no more 4wd issues.
.
Thanks again to everyone who gave me ideas and recommendations. :ylsmoke:

 

[kojackJKU]

sounds like your on the right track with that. I would replace it and see what happens!

 

[Burb One]

.
OK, just got back from our camping trip and I have some more data to add:
.
On Saturday we took a group of people out to the Sand Wash Basin in Northwestern CO to look for wild horses. Last year when we went out to the same area, it had recently rained and it was a muddy mess requiring us to be in 4wd a lot. This year it was pretty dry so we were all in 2wd.
.
At one point, we turned off the main road and onto a two track on soft soil. Just to be safe I switched to 4 hi, no issues. We explored that a short distance until it dead ended and then we turned around. Upon returning to the main road, I switched back to 2hi - and got the "Service 4wd" message. I cleared the code but as we were driving along slowly on a dirt road, I thought I'd "exercise" the system - but found out that it would not switch out of 2hi. Then we stopped for lunch and shut the vehicles off. When we started again, I pushed the button to shift to 4hi and it went into 4hi with no issues at all. However, when I switched it back to 2hi, I again got the "Service 4wd" message.
.
We didn't need 4wd for the next couple of days so I left it in 2hi. Then, on Tuesday a different group of us went out to see some petroglyphs on a very remote road (Vermillion Canyon, if you're familiar with the area. ) The road was on very soft dirt and very steep. I switched to 4hi for most of the 8 mile drive down and most of the way back - no issues and no warning messages. Near the bottom of a particularly steep hill, I actually switched it to 4lo. It went into 4lo with no issues and I was able to power right up to the top of the hill. When I got to the main road again, I switched back to 2hi with no problems and no warning messages. It hasn't given me the "Service 4wd" message since last Saturday.
.
From all the symptoms I'm seeing, I think 1st Deuce has it right - the problem is not the switch, it's the encoder motor and seems to be arising from lack of use. The more I used 4wd the fewer issues I had.
.
Now my only dilemma is whether to try to fix it myself or not. I did watch a YouTube video of an encoder motor replacement - it doesn't look terribly hard. For those who have done it, how difficult would you say it is?
.
As far as just replacing the ring goes, from what I've seen I'd still have to pull the entire encoder motor out anyway, right? My thought is that if I'm going to pull the whole thing out, I might as well replace the whole thing unless there is a huge cost difference. IIRC the entire encodor motor is a ~$200 part, right? Honestly I'd pay $200 if it meant no more 4wd issues.
.
Thanks again to everyone who gave me ideas and recommendations. :ylsmoke:

Agreed with kojack.

When I regeared my front diff I had to take out the motor. Took maybe 20 seconds? You can handle it haha

 

[Martinjmpr]

Agreed with kojack.

When I regeared my front diff I had to take out the motor. Took maybe 20 seconds? You can handle it haha

.
Just read through a write-up on the ring-sensor replacement (that does indeed require that you break open the encoder motor assembly.)
.
I'm a pretty fumble-fingered "mechanic" so the less I fumble with, the better things usually turn out. How much is a gen-u-wine GM encoder motor assembly? I see the Dorman motors on Flea-Bay for anywhere between $110 - $150. That's for the entire motor. The ring-only seems to run ~ $35.
.
Unless the factory encoder motor is a $500+ part (is it?) I would just think replacing the entire encoder motor at ~ $125 would be the better bet, wouldn't it? Any reason to really fuss with the interior of the motor assembly just to save $90? I would gladly spend the additional money to not be in that situation again. :ylsmoke:
.
EDITED TO ADD:
.
Looks like a genuine GM encoder motor assembly is about $250. Since it seems like others have had problems with the aftermarket motors I'll probably stick to the "real deal."
.
BTW I have to say I'm somewhat pleased that GM designed these to be user-serviceable. Over in the Toyota world if an electronic T-case malfunctions it's typically a $2500+ repair because they have to actually get inside the transfer case to fix it. :Wow1:

 

[Burb One]

EDIT- Doh, misread. I was talking about the forward Auto 4wd encoder. which is easier. This one I have not changed.. Looking into it, it doesn't seem too involved, but looks to be a tad harder than the front actuator...

 

[gwittman]

Martin, Rockauto.com has an AC Delco motor listed for just under $200. It states it is GM original equipment. It is for the NR4 transfer case which it sounds like what you have. You do have to pay shipping also but should not have to pay tax.

 

[Martinjmpr]

Martin, Rockauto.com has an AC Delco motor listed for just under $200. It states it is GM original equipment. It is for the NR4 transfer case which it sounds like what you have. You do have to pay shipping also but should not have to pay tax.

.
Gary: Mine is actually the NP8. Not sure what the NR4 is - that one may be for the Stabilitrak AWD transfer case. They do have the NP8 motor, though, $211 for a reman.