Go4Low
Well-Known Member
- Thread starter
- #1
Hope this helps someone in their search for potential causes of Intermittent SERV 4WD light.
My vehicle symptoms:
1. Transfer Case Switch (P/N: 5083138AA).
2. Star Buss Connector behind the Glove box: I decided to change both the green (P/N: 68321746AA) and white (P/N: 68140647AA) connectors. But in the long run the problem remained.
3. Wheel Speed Sensor: I ended up buying one front and one rear wheel speed sensor and started swapping. But the problem remained.
4. Rubbed wire around Transmission/Transfer case: I started inspecting wires, pulling and cleaning connectors with contact cleaner. But again, problem remained.
The solution at least for my situation:
I started checking ground posts and found that the nut on the ground connector located by the passenger side rear seat was loose. The ground post is beneath the plastic trim panel just before going up the wheel-well.
I was able to replicate the symptoms multiple times by removing the ground wire from the post. Once resecured, the symptoms would clear up.
It appears that even when this nut seems tight, it needs to be tightened down enough to where the inside base of the “U” wire connector is secured to the base of the ground post. I ended up torquing this 6mm nut to around 80 in-lbs., but it appears less (about 60 in-lbs.) would also do.
I don’t think it matter if it came like that from the factory, because apparently this ground post nut was secured enough for a long time until it either lost good enough contact or worked its way loose enough to cause all the above symptoms.
My vehicle symptoms:
- Intermittent SERV 4WD light.
- Intermittent going out of Transfer Case Dash Selector Lights (2H, 4H, N, 4L). Not necessarily going out when the SERV 4WD light comes on.
- Traction Control Light coming on.
- My SCAN Tool showed trouble codes with Fuel, CAT, EVA, 02S, ERG.
- Losing function of taillight.
1. Transfer Case Switch (P/N: 5083138AA).
2. Star Buss Connector behind the Glove box: I decided to change both the green (P/N: 68321746AA) and white (P/N: 68140647AA) connectors. But in the long run the problem remained.
3. Wheel Speed Sensor: I ended up buying one front and one rear wheel speed sensor and started swapping. But the problem remained.
4. Rubbed wire around Transmission/Transfer case: I started inspecting wires, pulling and cleaning connectors with contact cleaner. But again, problem remained.
The solution at least for my situation:
I started checking ground posts and found that the nut on the ground connector located by the passenger side rear seat was loose. The ground post is beneath the plastic trim panel just before going up the wheel-well.
I was able to replicate the symptoms multiple times by removing the ground wire from the post. Once resecured, the symptoms would clear up.
It appears that even when this nut seems tight, it needs to be tightened down enough to where the inside base of the “U” wire connector is secured to the base of the ground post. I ended up torquing this 6mm nut to around 80 in-lbs., but it appears less (about 60 in-lbs.) would also do.
I don’t think it matter if it came like that from the factory, because apparently this ground post nut was secured enough for a long time until it either lost good enough contact or worked its way loose enough to cause all the above symptoms.
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