"Service 4WD" anything to check before dealer trip?

[turboguy327]

I have a deleted and tuned 2012. Obviously I don't want them to know I'm deleted and tuned for warranty work. Anything I can check before I swap the exhaust out in 3 feet of snow and 10 degree weather for a dealer trip? I always use the tow/haul and exhaust brake. On the way home the tow/haul light on the dash was flickering/almost never illuminated. I turned the truck and key off and started back up and the light now works fine. Hopefully it's something easy somewhere. The truck has been running fine with no work for about a month now. I did open the hood to start wiring reverse lights but never got to any work as I had to leave due to a work emergency.

2012 ram 2500 mega cab. Automatic transmission cummins engine.

 0 Comment(s)

[DRD]

I have a deleted and tuned 2012. Obviously I don't want them to know I'm deleted and tuned for warranty work. Anything I can check before I swap the exhaust out in 3 feet of snow and 10 degree weather for a dealer trip? I always use the tow/haul and exhaust brake. On the way home the tow/haul light on the dash was flickering/almost never illuminated. I turned the truck and key off and started back up and the light now works fine. Hopefully it's something easy somewhere. The truck has been running fine with no work for about a month now. I did open the hood to start wiring reverse lights but never got to any work as I had to leave due to a work emergency.

2012 ram 2500 mega cab. Automatic transmission cummins engine.

I'll bet you anything its ice build up in the wheel speed sensors.

 0 Comment(s)

[turboguy327]

It did go plowing about 4 hours before the problem. But the light came on upon start up. Not during a drive. And it was in 2wd when I started it when the light came on.

 0 Comment(s)

[turboguy327]

It won't be above freezing until Sunday. So should I wait til then and see what happens? I did take it through a car wash and had no change. I'll see if I can pull it in somewhere to defrost. But wouldn't ice build up cause a ABS code not a 4WD code? And during movement not a startup?

 0 Comment(s)

[Polaraco]

It won't be above freezing until Sunday. So should I wait til then and see what happens? I did take it through a car wash and had no change. I'll see if I can pull it in somewhere to defrost. But wouldn't ice build up cause a ABS code not a 4WD code? And during movement not a startup?

Thats my suggestion. They tend to get a bit crazy in temps like that. Most of the time it's from cold starts and cold batts

 0 Comment(s)

[turboguy327]

Wasn't a cold start. I got home, opened the hood, got the lights and wiring and got the call and started it and got the light. I should have said that. Sorry. I drove about 2 hours before I parked it.

 0 Comment(s)

[DRD]

It did go plowing about 4 hours before the problem. But the light came on upon start up. Not during a drive. And it was in 2wd when I started it when the light came on.

Still could be as simple as ice. Condensation and freezing temps will do it. See the wheel sensors sense the rotation of the wheel hubs. They work only when there is a tolerance of clearance between the sensor and the rotating hub. Too much clearance or the touching of the two will cause the sensors to read faulty. The PCM will interpret as a service 4wd fault because hub bearing failures can cause this to happen as well...so it assumes the worst and tells you with the idiot light that somethings wrong with the 4wd.

 0 Comment(s)

[Polaraco]

Still could be as simple as ice. Condensation and freezing temps will do it. See the wheel sensors sense the rotation of the wheel hubs. They work only when there is a tolerance of clearance between the sensor and the rotating hub. Too much clearance or the touching of the two will cause the sensors to read faulty. The PCM will interpret as a service 4wd fault because hub bearing failures can cause this to happen as well...so it assumes the worst and tells you with the idiot light that somethings wrong with the 4wd.

True, but he'd get a anti-lock brake warning too. Sensors are double duty.

The front end sensors are located inside the bearing. It's more expensive, but a heck of allot more reliable than other designs.

I went through the FSM for my 03 and found no reference to "Service". Just fault codes. Do the key deal and check for codes. You may have an actuator not fully engaging or something else not going on too. It's not like the old days

 0 Comment(s)

[turboguy327]

I just scanned for codes with 2 scanners and found no stored codes? In the PCM or the BCM.

 0 Comment(s)

[turboguy327]

What would cause this without attempting to shift into 4WD? Not moving the truck either? I started it and it showed up. After working fine all night plowing.

 0 Comment(s)