1999 GMC Jimmy Repair Question
GMC Jimmy Sensor Problem
check the fuel pressure. it may be a bad pump.
The Crankshaft Position (CKP) Sensor is a sensor designed to detect changes in a magnetic field. The Control Module (PCM/VCM) supplies the CKP sensor a signal and ground circuits. Ignition voltage is supplied to the sensor by an independent circuit. The CKP sensor produces a magnetic field whenever the ignition is ON. The CKP sensor is mounted near a reluctor wheel that is attached to the crankshaft. When the crankshaft rotates (the engine is cranking or running) the toothed reluctor wheel changes the magnetic field. The CKP sensor converts each change in the magnetic field into a "pulse." The number of teeth on the reluctor wheel determines how many pulses the CKP sensor detects per crankshaft rotation. The CKP sensor signal is used to determine engine speed, crankshaft position, and detect misfire.
If a loss of the CKP signal or an erratic signal is detected by the VCM while the engine is running, this DTC will be set.
Conditions for Running the DTC
The MAF is 5 g/s or more.
Conditions for Setting the DTC
The measured change in engine speed is more than 1,000 RPM during a 125 ms time period, or
The measured engine speed is 0 RPM and 4 or more camshaft position sensor pulses have occurred over a period of 2 to 3 seconds
Action Taken When the DTC Sets
The Control Module illuminates the Malfunction Indicator Lamp (MIL) if a failure is detected during 2 consecutive key cycles.
The Control Module will set the DTC and records the operating conditions at the time the diagnostic fails. The Control Module stores the failure information in the scan tools Freeze Frame and/or the Failure Records.
Conditions for Clearing the MIL/DTC
The Control Module turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed.
A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22°C (40°F) from the start-up coolant temperature and the engine coolant temperature is more than 70°C (158°F) during the same ignition cycle).
Use the scan tool Clear Information function.
Inspect the face of the CKP sensor for metallic particles. This could result in an intermittent DTC.
Check for the following:
A chipped or damaged reluctor wheel
An incorrect reluctor wheel
The incorrect alignment of the CKP sensor to the reluctor wheel
Excessive crankshaft end play
Refer to Symptoms. See: Powertrain Management\Computers and Control Systems\Testing and Inspection\Symptom Related Diagnostic Procedures
An intermittent may be caused by any of the following conditions:
A poor connection
Rubbed through wire insulation
A broken wire inside the insulation
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis.
The numbers below refer to the step numbers on the
This step checks the ignition positive voltage circuit to the crankshaft position sensor.
This step checks the duty cycle of the crankshaft position sensor.
check the harness and the connector.
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