Damaged, corroded or loose wiring or connector at the gear shift module or on the communication line; Low battery voltage or poor power or earth supply to the gear shift module or transmission control unit; Faulty gear shift control module or selector assembly; Network communication fault such as a short, open circuit or bus fault affecting other modules; Water ingress or physical damage to the selector or module housing; Faulty transmission or engine control unit, or outdated software where the manufacturer has a known fix.

P0860

Gear Shift Control Module A Communication Circuit.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
8: AreaTransmission
60: FaultThe specific fault in that area

What it means

P0860 is a generic powertrain code meaning a fault has been detected in the communication circuit between the engine or transmission control unit and the Gear Shift Control Module A. The control unit that monitors the link has seen missing, corrupted or implausible messages, or the module has stopped responding. The exact module involved and how it is networked varies by model and transmission type.

Symptoms

Gearbox warning light or malfunction indicator lamp on
Gear selector position not shown correctly on the dash
Harsh, delayed or flared gear changes
Gearbox stuck in one gear or in limp mode
Manual shift mode, paddles or selector not responding
Car will not start or will not move out of park or neutral

Possible causes

Damaged, corroded or loose wiring or connector at the gear shift module or on the communication linelikely
Low battery voltage or poor power or earth supply to the gear shift module or transmission control unitlikely
Faulty gear shift control module or selector assemblypossible
Network communication fault such as a short, open circuit or bus fault affecting other modulespossible
Water ingress or physical damage to the selector or module housingpossible
Faulty transmission or engine control unit, or outdated software where the manufacturer has a known fixrare

How to diagnose

Read all stored codes and freeze frame data, and note whether other communication or network codes are present
Check battery condition and charging voltage, as low voltage commonly causes communication faults
Inspect the gear shift module, selector and its wiring and connectors for damage, corrosion, moisture or chafing
Check the power and earth supplies to the gear shift module against the wiring diagram
Test the communication circuit for continuity, short to earth or short to supply, following the model-specific procedure
Check live data to see whether the gear shift module is visible on the network and whether selector position changes are reported
Check for applicable service bulletins or software updates for the model and transmission
Clear the code and road test to see whether it returns, then recheck the data

How to fix

Repair or replace damaged wiring and clean or replace corroded connectors
Replace or recharge a weak battery and correct any charging or earth faults
Replace the gear shift module or selector assembly if it is confirmed faulty, with any required coding or adaptation done to the manufacturer's procedure
Repair the network fault found on the communication line
Dry out and seal any water ingress and replace any parts that have been damaged
Update the control unit software where a known fault is confirmed, or replace the control unit if proven faulty

Can I keep driving?

Medium severity

The car may be driveable but could change gear poorly or enter limp mode, so have it checked soon. Stop driving if the car will not hold a gear, will not select drive or reverse reliably, or the selector position is not clear.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.