P1400

DTC P1400: Manifold Differential Pressure Sensor Circuit Malfunction

Manifold Differential Pressure Sensor Circuit:

CIRCUIT OPERATION
- A 5-volt voltage is applied on the manifold differential pressure sensor power terminal (terminal No. 3) from the ECM (terminal No. 81). The ground terminal (terminal No. 2) is grounded with the ECM (terminal No. 92).
- A voltage proportional to the pressure in the intake manifold plenum is sent from the manifold differential pressure sensor output terminal (terminal No. 1) to the ECM (terminal No. 73).

TECHNICAL DESCRIPTION
- The manifold differential pressure sensor outputs a voltage which corresponds to the negative pressure in the intake manifold.
- The ECM checks whether the voltage output by manifold differential pressure sensor is within a specified range.

DESCRIPTIONS OF MONITOR METHODS
- An abnormal output of the manifold differential pressure sensor is detected through a comparison between the driving load and the manifold differential pressure sensor output.
- An open or short circuit is detected while monitoring the manifold differential pressure sensor output.

MONITOR EXECUTION
- Continuous

MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored in memory for the item monitored)
- Not applicable

Sensor (The sensor below is determined to be normal)
- Volume air flow sensor
- Intake air temperature sensor
- Engine coolant temperature sensor

DTC SET CONDITIONS

Logic Flow Chart:

Logic Flow Chart

Check Conditions
- 8 minutes or more have passed after starting the engine. Note that this is only if the engine coolant temperature is less than 0 °C (32 °F) when starting.
- Engine coolant temperature is higher than 45 °C (113 °F).
- Intake air temperature is higher than 0 °C (32 °F).
- Volumetric efficiency is between 30 and 45 percent.

Judgment Criteria
- Manifold differential pressure sensor output voltage has continued to be higher than 4.6 volts [corresponding to an absolute pressure of 118 kPa (34.8 in. Hg) or higher] for 2 seconds.

or

- Manifold differential pressure sensor output voltage has continued to be lower than 0.1 volt [corresponding to an absolute pressure of 2.4 kPa (0.3 psi) or lower] for 2 seconds.

DTC SET CONDITIONS

Logic Flow Chart:

Logic Flow Chart

Check Conditions
- 8 minutes or more have passed after starting the engine. Note that this is only if the engine coolant temperature is 0 °C (32 °F) or more when starting.
- Engine coolant temperature is higher than 45 °C (113 °F).
- Intake air temperature is higher than 0 °C (32 °F).
- Volumetric efficiency is higher than 70 percent.

Judgment Criteria
- Manifold differential pressure sensor output voltage has continued to be lower than 1.8 volts [corresponding to an absolute pressure of 46 kPa (4.6 psi) or lower] for 2 seconds.

OBD-II DRIVE CYCLE PATTERN
- Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 6 - Other Monitor. OBD-II Drive Cycle Pattern Lists

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Manifold differential pressure sensor failed.
- Open or shorted manifold differential pressure sensor circuit, harness damage, or connector damage.
- ECM failed.

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B

STEP 1. Using scan tool MB991958, check data list item 95: Manifold Differential Pressure Sensor

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Connect scan tool MB991958 to the data link connector.
2. Start the engine and run at idle.
3. Set scan tool MB991958 to the data reading mode for item 95, Manifold Differential Pressure Sensor.
- While engine is idling, pressure should be between 54 - 68 kPa (15.9 - 20.0 in.Hg).

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the sensor operating properly?

YES: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points.

NO: Go to Step 2.

STEP 2. Check harness connector B-102 at manifold differential pressure sensor for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 3.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 12.

STEP 3. Measure the sensor supply voltage at manifold differential pressure sensor harness side connector B-102.

1. Disconnect connector B-102 and measure at the harness side.
2. Turn the ignition switch to "ON" position.

3. Measure the voltage between terminal No. 3 and ground.
- Voltage should measure between 4.8 and 5.2 volts.

4. Turn the ignition switch to "LOCK" (OFF) position.

Q: Is the measured voltage between 4.8 and 5.2 volts?

YES: Go to Step 6.

NO: Go to Step 4.

STEP 4. Check harness connector C-115 at ECM for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 5.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 12.

STEP 5. Check for open circuit and short circuit to ground between manifold differential pressure sensor connector B-102 (terminal No. 3) and ECM connector C-115 (terminal No. 81).

Q: Is the harness wire in good condition?

YES: Replace the ECM. Then go to Step 12.

NO: Repair it. Then go to Step 12.

STEP 6. Check for continuity at manifold differential pressure sensor harness side connector B-102.

1. Disconnect connector B-102 and measure at the harness side.

2. Measure the continuity between terminal No. 2 and ground.
- Should be less than 2 Ohms.

Q: Does continuity exist?

YES: Go to Step 9.

NO: Go to Step 7.

STEP 7. Check harness connector C-115 at ECM for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 8.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 12.

STEP 8. Check for open circuit and harness damage between manifold differential pressure sensor connector B-102 (terminal No. 2) and ECM connector C-115 (terminal No. 92).

Q: Is the harness wire in good condition?

YES: Replace the ECM. Then go to Step 12.

NO: Repair it. Then go to Step 12.

STEP 9. Check harness connector C-115 at ECM for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 10.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 12.

STEP 10. Check for harness damage between manifold differential pressure sensor connector B-102 (terminal No. 3) and ECM connector C-115 (terminal No. 81).

Q: Is the harness wire in good condition?

YES: Go to Step 11.

NO: Repair it. Then go to Step 12.

STEP 11. Check for open circuit and short circuit to ground and harness damage between manifold differential pressure sensor connector B-102 (terminal No. 1) and ECM connector C-115 (terminal No. 73).

Q: Is the harness wire in good condition?

YES: Replace the manifold differential pressure sensor. Then go to Step 12.

NO: Repair it. Then go to Step 12.

STEP 12. Perform the OBD-II drive cycle.

1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 6 - Other Monitor. OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P1400 set?

YES: Repeat the troubleshooting.

NO: The procedure is complete.