DTC 73 Spark Retard Monitoring: Notes
When the need for ASR intervention is sensed by EBTCM, it supplies battery voltage to circuit No. 1687 to request spark retard by ECM.
If EBTCM senses an open, short to battery voltage or short to ground on circuit No. 1687, a DTC 73 will be set.
NOTE:
Test numbers refer to circled numbers on diagnostic chart.
- Checks for short to battery voltage in circuit No. 1687.
- Checks for short to ground in circuit No. 1687.
- Measures resistance in circuit No. 1687 and internal ECM (VIN J) or PCM (VIN P) circuitry.
- Checks for DTC reset after inspecting most of system.
- Determines if problem found in step 3) is due to an internally faulty ECM (VIN J) or PCM (VIN P) or an open in circuit No. 1687.