P0802
UniversalTransmission Control System Malfunction Indicator Lamp (MIL) Request Circuit / Open
Medium SeverityThis code indicates an open circuit in the Transmission Control Module (TCM) circuit responsible for requesting the Malfunction Indicator Lamp (Check Engine Light) to illuminate. While it doesn't directly cause driveability issues, it prevents the driver from being alerted to other potential transmission problems.
⚠️ Before You Begin (Safety First)
Always disconnect the battery before performing any electrical work. Be cautious when working around hot engine components or or moving parts.
Common Symptoms
- Malfunction Indicator Lamp (MIL) or Check Engine Light illuminated (if the ECM detects the open circuit)
- No obvious drivability issues
Common Causes
- Frayed, corroded, or open circuit in the MIL request wire between the TCM and ECM
- Loose or corroded connectors affecting the MIL request circuit
- Faulty TCM (less common, but possible)
- Faulty ECM (less common)
- Aftermarket accessories interfering with the electrical system
Frequently reported on: General/Universal
Diagnostic Steps
- Scan for all active and pending Diagnostic Trouble Codes (DTCs).
- Visually inspect the wiring harness and connectors associated with the Transmission Control Module (TCM) and Engine Control Module (ECM) for any signs of damage, corrosion, or loose connections.
- Locate the specific MIL request wire (refer to a vehicle-specific wiring diagram) and test its continuity using a multimeter.
- If an open circuit is found, repair the damaged wiring or replace the faulty connector.
- Clear the DTCs and retest the system.
👨🔧 When to Call a Professional
If after basic visual inspection you cannot locate a clear issue with wiring or connectors, or if you lack a multimeter to properly test circuit continuity, it is best to consult a professional mechanic.
Commonly Asked Questions
Can I drive with a P0802 code?
Yes, typically there are no immediate drivability issues. However, it's important to address it as it may prevent you from being alerted to other serious transmission problems.
What does "MIL Request Circuit / Open" mean?
It means the circuit that tells your Check Engine Light (Malfunction Indicator Lamp) to turn on when the transmission control system detects an issue has a break or interruption.
Do I need special tools to diagnose P0802?
A multimeter is essential for testing circuit continuity. A scan tool is also needed to read and clear codes.
Could a blown fuse cause this code?
While less common for a specific MIL request circuit, always check relevant fuses for the TCM or ECM power supply, as an open circuit could stem from a lack of power.
Is a faulty TCM always the cause of P0802?
No, it's more often a wiring or connector issue. A faulty TCM is a possibility but should only be considered after thoroughly checking the circuit integrity.