Diagnostic tool for SERV 4WD problems

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jeff6times7

Junior Member
Joined
Dec 24, 2023
Posts
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Location
Northeast Tarrant County Texas
Ram Year
2011
Engine
5.7L v8
I have a 2011 1500 SLT and the SERV 4WD becomes lit about 5 seconds after the ignition is set to ON or the motor is started. It stays lit until the ignition is in the OFF position. The transfer case motor appears to not be activated by any change to the selector on the dash and is stuck, thankfully, in the 2WD setting. I replaced the transfer case motor to no avail. I have a lousy PDF of the wiring diagrams that aren't legible. Is there a diagnostic tool that will expose problems that are not explained by a bad transfer case motor?

I've looked at this video but the description names 3 tools that might've been used but the video doesn't mention the tool that's used. Before wasting my time, I was hoping someone might know which tool would be helpful.

In this video, I found a test for the Drive Train Control Module. Both the pink wire and the yellow-orange wire both have 12V.
 
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