AIR CONDITIONER GP 5142708 - Caterpillar

Primary Engine Speed loss of signalNote: If the diagnostic code is logged but not active, run the engine until the engine is at normal operating temperature. The problem may only occur when the engine is at the normal operating temperature. If the engine will not start, monitor the engine rpm on Cat ET while the engine is being cranked. Cat ET may need to be powered from another battery while the engine is being cranked. This is done in order to ensure that Cat ET does not reset.Expected Result:The diagnostic code is logged or active.Note: If you have been directed here from Troubleshooting, "Troubleshooting without a Diagnostic Code" for the following reason, select "No Engine rpm":
The engine rpm was not indicated on Cat ET.Results:
, 190-2 - There is an active diagnostic code or a logged diagnostic code. Proceed to Test Step 4.
Not OK - Refer to the appropriate symptoms in the service manual.STOP
No engine rpm - Engine rpm is not indicated on Cat ET. Proceed to Test Step 3.Test Step 3. Check the Mechanical Condition of the Engine Speed/Timing Sensor
Turn the keyswitch to the OFF/RESET position.
Remove the suspect engine speed/timing sensor.
Inspect the plastic sliphead for damage.
Check the tension on the sliphead by gently prying out the sliphead 3 to 4 mm (0.12 to 0.16 inch). Push in the sliphead from the extended position.
Extend the sliphead.Expected Result:Pushing in the sliphead from the extended position takes at least 22 N (5 lb) of force.Results:
OK - The engine speed/timing sensor and the sliphead are undamaged. The tension on the sliphead is normal. Reinstall the sensor.Repair: Reinstall the engine speed/timing sensor. Refer to Disassembly and Assembly, "Speed/Timing Sensor - Remove and Install". Proceed to Test Step 4.
Not OK - The engine speed/timing sensor or the sliphead is damaged, or the sliphead has insufficient tension.Repair: Replace the engine speed/timing sensor. Refer to Disassembly and Assembly, "Speed/Timing Sensor - Remove and Install".Verify that the repair eliminates the problem.STOPTest Step 4. Check for Engine Speed on Cat ET
Turn the keyswitch to the ON position and crank the engine.
Observe the engine speed on Cat ET while you crank the engine.Expected Result:Cat ET should display a steady engine speed between 100 and 250 rpm while the engine is cranking and the engine should start.Results:
OK - The engine speed/timing sensor is operating normally at this time.Repair: Reconnect the known good engine speed/timing sensor.If you are troubleshooting an intermittent problem, refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
No Engine Speed - The engine does not start and the engine speed does not appear on Cat ET. Proceed to Test Step 5.
Engine Speed OK/Engine Will Not Start - The engine will not start. Engine speed appears on Cat ET.Repair: Reconnect the known good engine speed/timing sensor.Proceed to Troubleshooting, "Engine Cranks But Will Not Start".STOPTest Step 5. Check the Supply Voltage at the Sensor Connector
Install a three-pin breakout at the connector for the suspect engine speed/timing sensor.
Turn the keyswitch to the ON position.
Measure the voltage between terminal A (sensor supply) and Terminal