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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 123 (Engine Controls - Self-Diagnostics - 4.0L) >> Diagnostic Tests >> DTC P0335: Crankshaft Position Sensor "A" Circuit >> Test Description

Test Description

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers in the diagnostic procedures.

  1. 2

    This step determines if the 12-volt reference circuit to the CKP "A", the CKP "B", and the CMP is shorted to a ground. If all 3 DTCs are set, this indicates the circuit is shorted to a ground or a sensor is internally shorted. All 3 DTCs set because the 12-volt reference circuits are internally connected within the PCM. The engine will not start with this condition.

  2. 3

    DTC P0386 indicates an intermittent loss of the CKP "B" sensor signal while in Time "B" mode. DTC P0386 only sets after the PCM detects a loss of the CKP "A" sensor signal and has switched to Time "B" mode.

    During normal operation, the PCM uses the Angle Mode to determine engine position. In order to operate in this mode, the PCM must receive valid input from both CKP sensors. If the PCM detects a loss of the CKP "A" sensor signal, the PCM switches to a Time "B" mode using the CKP "B" sensor input in order to determine the engine position. If the PCM detects a loss of the CKP "B" sensor, the PCM switches to a Time "A" mode using the CKP "A" sensor input in order to determine the engine position.

  3. 4

    During engine operation, if moving the harnesses and connectors related to CKP "A" sensor results in a switch to Time "B" mode also causes an engine stall condition, an intermittent condition is present in the harnesses or in the connectors. If the harnesses and connectors are okay, CKP sensor "A" may be the cause of the intermittent condition.

  4. 7

    In order to test the CKP "A" sensor signal circuit, the PCM must be commanded to Time "A" mode using the scan tool. This allows the PCM to monitor input signals from CKP "A" sensor. For the procedures to selecting the Crank Decode Mode, see PROCEDURES FOR SELECTING CRANK POSITION SENSING DECODE MODE .

  5. 11

    This step determines if the CMP sensor is shorted internally. If the 12-Volt Reference parameter changes from Fault to okay, the condition is with the sensor.

  6. 12

    This step determines if the CKP "A" sensor is shorted internally. If the 12-Volt Reference parameter changes from Fault to okay, the condition is with the sensor.

  7. 13

    This step determines if the CKP "B" sensor is shorted internally. If the 12-Volt Reference parameter changes from Fault to okay, the condition is with the sensor.
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