PUMP AS-FUEL INJECTION 3116267 - Caterpillar

System Operation Description:Use this procedure to troubleshoot any suspect problems with the following sensors:
Primary engine speed/timing sensor
Secondary engine speed/timing sensorThis procedure covers the following diagnostic codes:
190-02 Loss of Engine Speed Signal
190-03 Engine Speed open/short to +batt
190-08 Engine Speed abnormal
342-02 Loss of Secondary Engine Speed signal
342-03 Secondary Engine Speed open/short to +batt
342-08 Secondary Engine Speed signal abnormalThe engine uses two engine speed/timing sensors. Both sensors detect the reference for engine speed and timing from a timing reference ring with a unique pattern that is on the rear face of the fuel injection pump gear. The Electronic Control Module (ECM) uses the pattern of the pulses in order to determine the position of the crankshaft. The ECM measures the time between the pulses that are created by the sensors as the gears rotate in order to determine rpm.Under normal operation, the primary speed/timing sensor determines when the piston in the No. 1 cylinder is at the top of the compression stroke. When the timing has been established, the sensor signal is used to determine engine speed.When the timing has been established, the ECM triggers each injector in the correct firing order at the correct time. The actual timing and duration of each injection is based on engine rpm and on load. The secondary speed/timing sensor provides continuous operation of the engine if the primary engine speed/timing sensor fails. If the engine is running and the signal from one sensor is lost, no change in engine performance will be noticed. If the engine is running and the signals from both sensors are lost, fuel injection will be terminated and the engine will be shut down by the ECM. The engine will start when only one sensor signal is present. The engine will not start if the signals from both sensors are lost.The engine speed/timing sensors receive supply voltage from the ECM that is regulated at 12.5 1.0 VDC. The engine speed/timing sensors provide a pulsed DC output voltage with a frequency that is directly proportional to engine speed. A unique tooth on the timing reference ring generates a duty cycle in order to provide the ECM with information on the crankshaft position.
Illustration 1 g01137012
Schematic for the engine speed/timing sensors
The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere.
Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
Illustration 2 g01137151
Top engine view (1) Timing calibration probe connector (2) P1/J1 ECM connector (3) Primary engine speed/timing sensor (4) Secondary engine speed/timing sensor
Thoroughly inspect connectors (1) and (2) .,Also inspect the connectors for speed/timing sensors (3) and (4). Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01137168
P1 ECM connector (P1-29) Digital return (P1-32) Speed/timing sensor supply (P1-38) Primary speed/timing sensor signal (P1-39) Secondary speed/timing sensor signal
Perform a 45 N (10 lb) pull test on each of the wires that are