Intermittent Service 4WD Light

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twfurst

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Feb 28, 2024
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Location
Griswold, CT USA
Ram Year
2012
Engine
6.7L Cummins
I have a 2012 3500 4x4 with 6.7L Cummins. I have been getting an intermittent 'SERVICE 4WD SYSTEM' message and warning light on the dash. It seems to happen only after driving at steady speeds, and will go away once the vehicle comes to a stop. This has been going on for almost a year.

I have read that it could be a few different items:
  • Transfer case actuator
    • Are there any specific signs/symptoms I should be looking for? I have not had any issues with the 4WD working at all, nor have I had any issue with the cruise control working (I had read that in some instances when this light comes on that CC can get disabled). Really hoping this is not the issue, as I understand that this item requires a VIN programming at the dealer ($$$$).
  • Vehicle Speed Sensor
    • Both front hubs have been replaced on this truck. One prior to 100K and the other around 150-175K. With the cost of these around $500 now, not really trying to just swap them out to see if it resolves it, to find it doesn't.
  • Wiring issue
    • I have not crawled under the truck to look at the wiring for the t-case yet. The post where I saw that a broken wire was the culprit was for a '16 2500 model, and I believe they have different configuration as I do not have wiring at my front axle like that post depicted.
  • Drivetrain Control Module
    • Don't even want to begin to think about what the cost of this thing is...
The fact that it happens after either 'spirited' use, lengthy steady drive time/speed leads me to believe that it is related to heat. Whether that is an issue in the hubs or t-case is what I am not sure of how to isolate/pinpoint. It has only been initiated by hitting a bump once (massive pothole on I95 in the Bronx).

The truck has 206K on it and I am trying to keep it for quite a few more. Love the truck, just want to get this 'bug' worked out. I live in CT and have driven it to Chicago twice, Tennessee more times that I can count, North Carolina. I love driving it, just want to get it back to not yelling warnings at me. Hoping I can get some experiences from this community as well as solutions.
 

Brandon-w

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Yukon
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2015 Ram 1500
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6.4
My 2015ram does this too. I'm I'm racing or at 100% throttle for any amount of time over 60mph it'll come on weather in 4x4 or not my dealership chased this for a couple Hrs charged me $300 and said it's not designed to be driven like that. Go figure.... The best part is when I habe this issue there are no codes present and once I slow down to under 50mph it goes out like it was never ever even there. It's now just an annoying part of life.
 

smittyd174

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Halifax
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2022
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5.7 hemi
I had a 2016 3500 with the Cummins. Mine started doing that and you could hear a faint noise from the front axle . Did a little looking on the forums and decided to try simple first . Unplugged the connection for the axle actuator cleaned both sides with contact cleaner let it dry applied a little dielectric grease and plugged it back in , problem solved , took 10 minutes. Never happened again . Moisture gets in the connection and when it gets hot trips the light .
 

Philip Gao

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Location
Canada
Ram Year
2012 Ram 1500
Engine
Hemi 5.7

Service 4WD Light, you can use an OBDII reader to scan the details information, even you can use it monitor your ABS SPEED CHART, so you can have a very details information to avoid a lot of trying, myself bought a BlueDriver OBDII scan, at least $100 level OBDII scan tool can read the ABS information​

In my case, scan message: drive side rear ABS failed or ABS cable broken, the final problem is:
1 ABS module lost a resistor, so this make a wheel ABS data lost
2 the rear Axle has a broke ABS speed ring

I do ABS sensor replace, this doesn't work for the true situation.
 
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twfurst

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Feb 28, 2024
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Location
Griswold, CT USA
Ram Year
2012
Engine
6.7L Cummins
I had a 2016 3500 with the Cummins. Mine started doing that and you could hear a faint noise from the front axle . Did a little looking on the forums and decided to try simple first . Unplugged the connection for the axle actuator cleaned both sides with contact cleaner let it dry applied a little dielectric grease and plugged it back in , problem solved , took 10 minutes. Never happened again . Moisture gets in the connection and when it gets hot trips the light .
I have read something similar before, but I do not believe I have this front axle actuator. I do not see any electrical connections for the front axle.

Just put ~2500 miles on it driving from CT to TN and back. Light came on after about 2 hours of driving on the way down and remained on for duration of interstate driving. Same happened on the return trip, except that after my first fuel stop it never came back on again.
 

smittyd174

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Halifax
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2022
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5.7 hemi
If it's 4wd I would say it's there . It's on the passenger side of the axle top backside about 4 inches or so from the pumpkin. It's a rectangular plate with one plug assembly on it . Goodluck.
 

smittyd174

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2022
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5.7 hemi
It has a round tube like gizmo attached to it , been a while since I did it and no longer have that truck . Lots of vids on utube
 
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