BELT-SERPENTINE 3590189 - Caterpillar

Illustration 2 g03781728
Typical left side engine view
(1) Rear surface of the front timing gear housing
(2) Mounting flange
(3) Bracket
Table 3
Troubleshooting Test Steps Values Results
5. Inspect the Sensor Assembly
A. Turn the keyswitch to the OFF position.
B. Visually inspect the sensor and the sensor assembly without removing the sensor assembly from the engine. Flanges (2) must be flush against the surface of the front timing gear housing (1) in order to ensure proper operation.
C. Inspect bracket (3). Verify that the bracket securely holds the flanges of the sensors flush against the engine.
D. Verify that the bracket is not bent. If the bracket is bent or if an obstruction is preventing the sensor assembly from being installed correctly, the engine will not start.
E. Disconnect the harness from the speed/timing sensors. Check the harness for debris and for corrosion.
F. Perform a 45 N (10 lb) pull test on the harness wiring.
Sensor Inspection
Result: The sensor and the sensor assembly mounting are OK.
Do not reconnect the harness connector. Proceed to Test Step 6.
Result: The sensor and/or the sensor assembly has a mechanical problem or the harness has debris and/or corrosion.
Repair: Repair the sensor and/or the sensor assembly or replace the sensor and/or the sensor assembly.
Repair: Replace the sensor and the sensor harness connector if there was debris and/or corrosion.
Verify that the problem is resolved.
Illustration 3 g02207317
Typical left side engine view
(5) Connector for the primary engine speed/timing sensor
(6) Connector for the secondary engine speed/timing sensor
Illustration 4 g01218763
Terminal locations at the connector for the speed/timing sensors
(1) Engine speed/timing signal (−)
(2) Engine speed/timing signal (+)
Table 4
Troubleshooting Test Steps Values Results
6. Use a Multimeter to Check the Harness Wiring
A. Turn the keyswitch to the ON position.
B. Perform the following procedure for each sensor.
1. Measure the voltage between terminal 1 and a good engine ground. The voltage is 2.4 0.2 VDC.
2. Measure the voltage between terminal 2 and a good engine ground. The voltage is 2.4 0.2 VDC.
Wiring
Result: The voltage was OK for all of the measurements.
The harness and wiring are OK. Proceed to Test Step 7.
Result: The voltage was not OK for at least one of the measurements.
There is a problem in the harness wiring.
Repair: Repair the appropriate harness wiring or replace the appropriate harness.
Verify that the problem is resolved.
7. Measure the Resistance of the Sensor
A. Turn the keyswitch to the OFF position.
B. Disconnect the engine harness from the sensor.
C. Remove the sensor. Check the sensor tip for any damage.
D. For the primary engine speed/timing sensor, measure the resistance between terminal 2 (Primary engine speed/timing +) to terminal 1 (Primary engine speed/timing −).
Resistance: 75 Ohms to 230 Ohms
E. For the secondary engine speed/timing sensor, measure the resistance between terminal 2 (secondary engine speed/timing +) to terminal 1 (secondary engine speed/timing −).
Resistance: 600 Ohms to 1800 Ohms
Sensor Resistance
Result: The resistance measurement for the sensor is within the specification. There is no damage to the sensor tip.
If the engine was running before removing the sensor, reinstall the sensor.
Use Cat ET to check for any active diagnostic codes. Troubleshoot any active diagnostic codes.
Return