Technical Definition:

Transmission Control System (Malfunction Indicator Light (MIL) Request)

Technical Description:

The vehicles have a control module for the automatic transmission called a transmission control module (TCM). The engine control module (ECM) communicates with the TCM to monitor the automatic transmission for faults. If the TCM detects a fault in the automatic transmission and sets a transmission related fault code, the ECM is informed of this also and sets a P0700 in the ECM memory.

Possible Causes:

Possible Symptoms:

• Malfunction Indicator Lamp (MIL) illumination
• The transmission may exhibit drivability problems like slipping, etc.

Transmission Control System Malfunction

Possible Solutions:

OBD-II Trouble Code Type:

Diagnostic Step:

Tech Notes:

– Shorted or open circuit within Transmission Control Module (TCM)
– Faulty Transmission Control Module (TCM)

Specific Makes:

– Driveability problems
– Transmission shifting problems