## Diesel Engine Management System

#### DTC Troubleshooting (cont'd)

11-65

DTC P0237: Manifold Absolute Pressure (MAP) Sensor Circuit Low Voltage

1. Check the ''On Board Diagnostic (OBD) System Check''.

Was the ''OBD System Check'' performed?

YES – Go to step 2.

NO – Go to OBD System Check.

1. Check the DTC.

Are there any other (beside DTC P0237) being output?

YES – Go to relevant DTC chart.

NO – Go to step 3.

1. Check the DTC.

Are there other DTCs P1627, P1618 (beside DTC P0237) being output?

YES – Go to DTC P1627, P1618 chart (5 V reference #2 circuit failure).

NO – Go to step 4.

1. Turn the ignition switch ON (II).

1. Check the MAP with the scan tool.

Is about atmospheric pressure indicated?

YES – Go to step 6.

NO – Go to step 8.

1. Start the engine and allow it to idle.

1. Check the MAP with the scan tool.

Is about 20 – 30 kPa (150 – 225 mmHg, 5.9 – 8.9 in. Hg) indicated?

YES – Intermittent failure, system is OK at this time. Check for poor connections or loose wires at the MAP sensor and at the ECM.

NO – Go to step 8.

1. Check for the following conditions:

- Damaged MAP sensor
- The vacuum hose work at MAP sensor for leaks
- The PCV system vacuum leaks
- An incorrect PCV valve
- Vacuum leaks in EGR valve flange and pipes
- Intake manifold vacuum leaks

Is a problem found?

YES – Repair as necessary.

NO – Go to step 9.

1. Turn the ignition switch OFF.

1. Disconnect the MAP sensor 3P connector.

1. Measure voltage between the MAP sensor 3P connector terminals No. 1 and No. 3.

Wire side of female terminals

MAP sensor 3P connector

Is there about 5 V?

YES – Replace the MAP sensor.

NO – Go to step 12.

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