TUBE (46.04" Long) 9K2857 - Caterpillar

System Operation Description:The Crank Angle Sensor (CAS) is a passive magnetic sensor. The sensor indicates the crankshaft angle to the Timing Control Module (TCM). The sensor provides the top center (TC) signal to the TCM. The TCM uses this signal to calculate the actual timing and the engine speed.The output of the speed sensor is a sinusoidal pulse. The pulse is initiated when the hole in the flywheel for the TC position passes beneath the sensor. The frequency of occurrence of the pulse is proportional to the speed of the engine.The TCM diagnoses open conditions and short conditions for the CAS by monitoring the characteristic resistance of the sensor.
Illustration 1 g00664465
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For the actual configuration of the wiring, see the engine's wiring diagram.Test Step 1. Check for Connector Damage.
Remove the power from the timing control system.
Check the connectors and wiring for the following problems: damage, corrosion, abrasion and incorrect attachment. Refer to Troubleshooting, "Inspecting Electrical Connectors".Expected Result:The connectors and wiring are free of the following problems: damage, corrosion, abrasion and incorrect attachment.Results:
OK - The connectors and wiring are in good condition. Proceed to test step 2.
Not OK - The connectors and/or wiring require service.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Stop.Test Step 2. Check the CAS.
Disconnect the CAS from the engine harness.Note: Be sure that you measure the resistance at the sensor connector. Do not measure the resistance at the harness connector.
Use the scale of 4000 ohms to measure the resistance between pin A and pin B at the sensor connector.Expected Result:The resistance is between 100 and 600 ohms.Results:
OK - The resistance is correct. Proceed to test step 3.
Not OK - The resistance is not correct.Repair: Replace the CAS. Stop.Test Step 3. Check the Harness.
Connect the CAS to the engine harness.
Disconnect the TCM from the engine harness.
Measure the resistance at the harness connector for the TCM. Use the scale of 4000 ohms to measure the resistance between pin L and pin N.Expected Result:The resistance is between 100 and 600 ohms.Results:
OK - The harness is OK. Proceed to test step 4.
Not OK - There is a problem in the wiring harness.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Stop.Test Step 4. Check the Clearance Between the CAS and the Flywheel.
Disconnect the CAS from the engine harness.
Mark the position of the CAS.
Loosen the locknut.
Turn the sensor clockwise until the sensor contacts the flywheel.Record the number of turns that are required to make contact. One-half to three quarters of a turn (180 to 270 degrees) are required to obtain the proper clearance.
Remove the sensor from the flywheel housing.
Inspect the sensor for damage and for metal filings on the magnetic tip.
Install the CAS.
Turn the sensor clockwise until the sensor contacts the flywheel face.
Turn the sensor in a counterclockwise direction for approximately one-half to three quarters of a turn (180 to 270 degrees).Note: Do not allow the sensor to move when you tighten the locknut.
Tighten the locknut.
Connect the CAS to the engine harness.Results:
OK - The