"Set Timing Mode" Message

Wiring Diagram:

CIRCUIT DESCRIPTION

Set timing mode is a service aid designed into the fuel control system to allow spark advance to be disabled. If pin 'B' of the Data Link Connector (DLC) connector is grounded, the PCM will sense a ground on CKT 462 and enter set timing mode as long as the engine is running, the transmission is in park or neutral, and the engine RPM is below 900. When these conditions are met, the PCM will indicate to the IPC over the Universal Asynchronous Receiver Transmitter (UART) data line to display the 'SET TIMING MODE' message.

TEST CONDITION(S)

None

FAILURE CONDITION(S)

1. IPC receives set timing bit from PCM.

ACTION TAKEN

1. Display 'SET TIMING MODE' message on DIC.

DIAGNOSIS

Ensure CKT 462 (pin 'B' at DLC to PCM) is not grounded.