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DTC P0340
CIRCUIT DESCRIPTION
The hall effect camshaft position (CMP) sensor produces 3 ON-OFF pulses for each revolution of the camshaft. The CMP output is pulse width encoded. The electronic control (ECM) module uses the CMP and crankshaft position (CKP) output pulses to determine the engine speed and position. The CMP is connected directly to the ECM by the following circuits:
12-volt reference
Low reference
CMP sensor signal
If the ECM does not see a CMP signal for more than 2 seconds, DTC P0340 will set.
CONDITIONS FOR RUNNING THE DTC
The ignition is ON.
The engine is turning faster than 50 RPM.
CONDITIONS FOR SETTING THE DTC
The ECM does not see a CMP sensor signal for more than 2 seconds.
ACTION TAKEN WHEN THE DTC SETS
The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.
DIAGNOSTIC AIDS
An intermittent CMP sensor signal may cause DTC P0340 to set. Wiggle the wiring harness with the engine running and observe the Cam Signal Missed parameter of the scan tool. If the parameter indicates anything other than 0, there is an intermittent condition.
A short from the 12-volt reference circuit to the low reference circuit internally in the camshaft position (CMP) or crankshaft position (CKP) sensor can cause all three DTCs P0336, P0340, and P0016 to set.
If the CMP sensor signal is lost while running, the engine will operate normally. If the CMP sensor signal is not present on start-up, the engine will not start.
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