Gear Shift Module Communication Circuit High
Your car's transmission control module isn't communicating properly with the main computer—the signal is too strong or stuck high. Think of it like a phone line that's constantly shouting instead of having a normal conversation.
The ECM monitors the voltage signal from the Gear Shift Module (GSM) communication circuit. It expects the signal to toggle between high and low states within normal voltage ranges to confirm proper two-way communication. A persistently high voltage indicates a wiring short, stuck relay, or GSM module failure.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| GSM Circuit Voltage | 0.5-4.5V (toggling) | Held above 4.8V continuously |
| Signal Response Time | <100ms transition | >500ms or no transition |
Code P0862 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0862 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.