RING 8C7440 - Caterpillar

System Operation Description:The detonation sensors are powered by +13 VDC from the EIS control module. This voltage is also provided to these sensors:
Speed/timing sensor
Inlet manifold pressure sensorEach detonation sensor creates a signal that is equivalent to the engine's mechanical vibrations. The frequency of the signal is equal to the frequency of the vibrations. The amplitude of the signal is proportional to the intensity of the vibrations. The EIS control module evaluates the signal for the proper characteristics.Low Signal Strength - The control module will generate a -01 diagnostic code for the appropriate sensor.High Signal Strength - Detonation is occurring. The control module will generate a 326-01 diagnostic code. If detonation becomes excessive, the control module will generate a 325-01 diagnostic code.Short to a Positive Voltage Source - The signal wire is shorted to a positive voltage source. The control module will generate a -03 diagnostic code for the appropriate sensor.Short to Ground or Open Circuit - The signal wire has an open circuit or a short to ground. The control module will generate a -05 diagnostic code for the appropriate sensor.Detonation Retarded TimingIf detonation occurs, the control module will retard the timing in order to stop detonation from occurring. The control module can retard the timing by as little as 3 degree for light detonation. The control module can retard the timing by a maximum of 25 degrees for severe detonation.A proportional strategy is used to advance the timing out of detonation retard. The rate of advance depends on the severity of the detonation. If the detonation level is low, the advance rate is faster. The fastest rate of timing advance out of detonation is two degrees per minute.If detonation occurs, the control module will perform the following actions:
Continuously illuminate the "" lamp.
Activate a 326-01 diagnostic code.
Retard the ignition timing.If the ignition timing is fully retarded and severe detonation continues, the control module will perform these actions.
Continuously illuminate the "SHUTDOWN" lamp.
Activate a 325-00 diagnostic code.
Activate the "Shutdown Relay Output".
Illustration 1 g01159778
Schematic diagram of the detonation sensorsTest Step 1. Inspect the Electrical Connectors and Wiring
Set the engine control to the OFF/RESET mode. Remove the electrical power from the engine.Note: For the following steps, refer to Troubleshooting, "Inspecting Electrical Connectors".
Thoroughly inspect each of the following connectors:
Connectors for the EIS control module
Connectors for each detonation sensor
J6/P6 connectors on the junction box (if equipped)
Illustration 2 g01044156
Harness side of the EISC connector (EISC-E) Signal from the right detonation sensor (EISC-H) Signal from the left detonation sensor (EISC-M) 13 VDC for the right detonation sensor (EISC-P) 13 VDC for the left detonation sensor (EISC-Y) Ground for the left detonation sensor (EISC-d) Ground for the right detonation sensor
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit for the detonation sensors.
Illustration 3 g01044294
Detonation sensor (1) Buffer module (2) Accelerometer (3) Wiring
Check the wiring (3) between each accelerometer (1) and each buffer module (2) for corrosion, for abrasion, and