P0340

DTC P0340: Camshaft Position (CMP) Sensor Circuit Malfunction

Wiring Diagram










System Description

The CMP sensor located on the transmission side of cylinder head consists of the signal generator (photo transistors) and signal rotor (slits plate).

The signal generator generates Reference signal and Position signal through two types of slits in the slit plate which turns together with the camshaft.

Reference signal

The CMP sensor generates 4 pulses of signals each of while has a different waveform length while the camshaft makes one full rotation.

Based on these signals, ECM judges which cylinder piston is in the compression stroke.

Position signal

The CMP sensor generates 360 pulses of signals while the camshaft makes one full rotation (i.e., 1 pulse per 1 ° movement of the camshaft).

Based on these signals, ECM judges the waveform length of Reference signal, the engine speed and piston position.

DTC Detecting Condition and Trouble Area






DTC Confirmation Procedure

NOTE:

Check to make sure that the following conditions are satisfied when using this DTC confirmation procedure.

- Intake air temp.: -14 °C, 6.8 °F or higher
- Altitude (barometric pressure): 2020 m, 6650 ft or less (540 mmHg, 72 kPa or more)

1) With ignition switch turned OFF, connect scan tool.
2) Turn ON ignition switch and clear DTC using scan tool.
3) Crank engine for 5 sec. or more.
4) Check DTC and pending DTC.

DTC Troubleshooting

1.
Was "Engine System Check" performed?
YES
Go to Step 2.
NO
Go to Engine System Check Engine System Check.

2.
Is engine cranked?
YES
Go to Step 3.
NO
Go to Cranking System Symptom Diagnosis.

3. Engine start signal check.

Check engine start signal circuit referring to Step 2 of P1500 DTC P1500: Engine Starter Signal Circuit Malfunction.

Is the result satisfactory?
YES
Go to Step 4.
NO
Repair or replace.

4. Check CMP sensor power supply voltage.

Disconnect connector from CMP sensor (1) with ignition switch turned OFF
Turn ON ignition switch, measure voltage between "BLK/ORN" and "BLK/RED" wire terminal.






Is voltage 10 - 14 V?
YES
Go to Step 8.
NO
Go to Step 5

5. Check CMP sensor power supply voltage.

Turn ON ignition switch, measure voltage between engine ground and "BLK/RED" wire terminal.

Is voltage 10 - 14 V?
YES
Go to Step 6.
NO
"BLK/RED" wire in open circuit.

6. Check CMP sensor ground circuit.

Measure resistance between "BLK/ORN" wire terminal and engine ground.

Is resistance below 5 ohms?
YES
Go to Step 8.
NO
Go to Step 7

7. Check ground circuit.

Disconnect connectors from ECM with ignition switch turned OFF
Remove ECM from vehicle body and connect connectors to ECM.
Measure resistance between "C45-26" terminal and vehicle body ground.

Is resistance below 5 ohms?
YES
"BLK/ORN" wire in open or high resistance circuit
NO
ECM grounds "C45-26" and/or "C46-9" circuit in open or high resistance.
If wires are OK, substitute a known-good ECM and recheck.

8. Check CMP sensor reference signal circuit.

Turn ON ignition switch.
Measure voltage between "YEL/RED" wire terminal in CMP sensor and engine ground.

Is voltage 4 - 5 V?
YES
Go to Step 11.
NO
Go to Step 9.

9. Check CMP sensor signal circuit.

Disconnect connectors from ECM with ignition switch turned OFF.
Measure resistance insulation between "YEL/RED" wire terminal and vehicle body ground.

Is resistance infinity?
YES
Go to Step 10.
NO
"YEL/RED" wire shorted to ground circuit.

10. Check CMP sensor signal circuit.

Measure voltage between "YEL/RED" wire terminal and vehicle body ground.

Is voltage 0 V?
YES
"YEL/RED" wire open circuit.
NO
"YEL/RED" wire shorted to other circuits.

11. Check CMP sensor signal circuit.

Measure resistance between "YEL/RED" wire terminal in CMP sensor connector and "C46-10" terminal in ECM connector.

Is resistance below 3 ohms?
YES
Go to Step 12.
NO
"YEL/RED" wire in high resistance circuit.

12. Check CMP sensor reference signal circuit.

Turn ON ignition switch.
Measure voltage between "BLU" wire terminal in CMP sensor and engine ground.

Is voltage 4 - 5 V?
YES
Go to Step 15.
NO
Go to Step 13.

13. Check CMP sensor signal circuit.

Disconnect connectors from ECM with ignition switch turned OFF.
Measure resistance insulation between "BLU" wire terminal and vehicle body ground.

Is resistance infinity?
YES
Go to Step 14.
NO
"BLU" wire shorted to ground circuit.

14. Check CMP sensor signal circuit.

Measure voltage between "BLU" wire terminal and vehicle body ground.

Is voltage 0 V?
YES
"BLU" wire open circuit.
NO
"BLU" wire shorted to others circuit.

15. Check CMP sensor signal circuit.

Measure resistance between "BLU" wire terminal in CMP sensor connector and "C46-22" terminal in ECM connector.

Is resistance below 3 ohms?
YES
Go to Step 16.
NO
"BLU" wire in high resistance circuit.

16. Check CMP sensor signal circuit.

Using oscilloscope, check CMP sensor waveform referring to following reference.

Is it good condition?
YES
Faulty ECM.
Substitute a known-good ECM and recheck.
NO
Faulty CMP sensor.

Reference

Connect oscilloscope between C46-10 (Reference signal) or C46-22 (Position signal) and C45-26 and check CMP sensor signals.

[A] Reference waveform

CMP sensor signal at engine idling.
















[B] Reference detail waveform

CMP sensor signal at engine idling.