P0861: Gear Shift Control Module A Communication Circuit Low
What to do
Expect the selector to be ignored and several warning lights at once. That breadth is a clue rather than a catastrophe — a single shorted wire silences everything on the same circuit.
What this code means
The gear shift module's communication circuit is held low, normally a short to ground. A bus line shorted low does not just silence one module — it prevents every module sharing that line from transmitting, because none of them can drive the line to the level a message requires.
So the presence of communication codes from several unrelated modules alongside this one is not evidence of several failures. It is the signature of a single short, and chasing the modules individually is exactly the wrong response.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Damaged data bus wiring · specialist
Less common
- Faulty gear shift module · specialist
- Liquid spilled into the gear selector · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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