ELECTRICAL SYSTEM TESTS, INSPECTIONS, AND ADJUSTMENTS - CONTINUED
ENGINE SPEED/TIMING SENSOR CIRCUIT TEST
N OT E
· Use this test to troubleshoot system if there is active diagnostic code or easily repeated diagnostic code associ-
ated with engine speed/timing sensors.
· Engine uses two engine speed/timing sensors. One sensor is located in cylinder block. Speed/timing sensor
mounted on cylinder block measures crankshaft speed and calculates position of crankshaft. ECM counts
time between pulses created by sensor as gear rotates to determine rpm.
· Second speed/timing sensor is located in fuel injection pump. Speed/timing sensor measures speed and posi-
tion of fuel injection pump.
· ECM uses both sensor signals to calculate engine speed and correct engine timing.
· Engine will start and run when only one sensor signal is present from either sensor. Loss of signal from both
sensor during engine operation will result in termination of injection and shutting down of engine by ECM.
Loss of signal from both sensor during start-up will prevent engine from starting.
Inspect electrical connectors and cables. Refer to WP 0067 00 and WP 0053 00. Refer to Electrical Connectors Inspec-
tion (WP 0022 00).
Inspect electrical connectors for damage.
Expected Results. Electrical system is free from damage and faults.
If results are OK, there is no damage or faults. Proceed to step 2.
If results are NOT OK, there is damage to electrical system components.
(a) Replace wiring harness in question (WP 0169 00 thru WP 0175 00).
(b) Ensure all seals are in place and connectors are correctly installed.
(c) Verify repair has eliminated fault. If fault is not eliminated, proceed to step 2.
Check installation of engine speed/timing sensors.
Turn engine start switch to OFF position (TM 5-
Refer to Electrical Connectors Inspection (WP
Engine speed/timing sensor must be installed
with metal plate flat against cylinder block to
Ensure O-rings have been installed on sensor
properly and are not damaged (WP 0067 00).
Install and reconnect sensors.