DTC 12

Code 12-ECM Power Supply:

Code 12-No Reference Pulses to ECM:

Code 12 is indicated when there are no ignition reference pulses to the ECM. This code is not stored in memory and will only flash while the fault is present and before the engine is started. Code 12 will also flash when the trouble code test lead is grounded with the ignition "ON" and engine not running. In this mode, code 12 will flash to indicate that the on-board diagnostic system is functioning.

Ignition Coil Wire Connector:

1. Check coil connections for corrosion, fully seated connector terminals and terminals not properly attached to the wire. Remove connector from terminal and inspect carefully.

Checking Reference Pulse Voltage:

2. Check for good contact at terminal C46-10 of the ECM. Normal reference pulse voltage being sent to the ECM should be over 10V.