The Electronic Control Module (ECM) detects at least one of the following conditions:
- The pattern of the timing ring is lost without a ramp down in engine speed.
- The pattern of the timing ring returns within one second of being lost.
- Battery voltage is less than 9 V for the last two seconds.
OR
The ECM will log a diagnostic code, and the ECM will have an active diagnostic code if the ECM detects all of the following conditions:
- There is an invalid pattern for the timing ring for one second.
- The secondary engine speed/timing sensor has a valid pattern for the timing ring.
- The secondary engine speed/timing sensor has a signal that is greater than 100 rpm.
- Battery voltage is less than 9 V for the last two seconds.
System Response:
The ECM will log the diagnostic code. The ECM may have an active diagnostic code. The diagnostic code may be viewed on a display module or on the Caterpillar Electronic Technician (ET). If a valid signal is not received from the primary engine speed/timing sensor, the ECM will default to the secondary engine speed/timing sensor.
Possible Performance Effect:
- Engine misfires
- Engine shutdown
Note: The engine will shut down only if both the primary engine speed/timing sensor and the secondary engine speed/timing sensor fail.
Troubleshooting:
Test Step 1. Perform the following diagnostic procedure: "Engine Speed/Timing Sensor Circuit - Test"
Results:
- OK - STOP