DTC 12

Fig. 007 - Wiring Diagram for Code 12 No Distributor Reference Pulse To The ECM. VIN C:

CODE 12, NO DISTRIBUTOR REFERENCE PULSE TO THE ECM

The distributor provides a tach signal to the ECM through a filter indicating engine RPM. Tachometer must only be connected to the distributor side of the filter.

Fig. 006 - Chart Code 12 No Distributor Reference Pulse To The ECM.:

1. This step checks for a poor connection at the tach filter wire connector as being the source of no distributor reference pulse. Check for corrosion at connector terminals not fully seated, or terminal not properly attached to the wire. The terminal must be removed from the connector and carefully inspected.
2. This step determines if a reference pulse voltage is being sent to the ECM. Normal voltage should be over one volt. Check for good terminal contact at terminal "19" of the ECM.
3. This step checks voltage from distributor through the tach fiter. Voltage should be above 10 volts.
4. This step checks voltage from distributor. Voltage should be above 10 volts.