Code 12, No Distributor Reference Pulses
This is a normal code with the ignition on and engine not running. With engine running, Code 12 could mean an open or ground in distributor reference circuit. Code 41 will appear with Code 12 if engine is running with no distributor reference signal. Code 41 will be stored even if problems clear.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- This tests if a poor connection at EST connector is the cause of no reference pulse. Terminal must be removed from connector and carefully inspected.
- Voltage should be more than .5 volt. This indicates reference signal is being generated by module and fault is either a bad connection at ECM or a faulty ECM. To check ECM connection, terminal must be removed from ECM connector.
- If circuit No. 430 from terminal No. 10 to module is not open or grounded, source of no signal is the module.