## Diesel Engine Management System

#### DTC Troubleshooting (cont'd)

11-114

DTC P1235: Manifold Absolute Pressure (MAP) Sensor Supply Voltage High/Low

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 other DTCs P1628, P1627 (beside DTC P1235) being output?

YES – Go to step 3.

NO – Clear DTC P1235 by the scan tool.

1. Turn the ignition switch ON (II).

1. Check the MAP with the scan tool.

Is about atmospheric pressure indicated?

YES – Go to step 5.

NO – Go to step 7.

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 7.

1. Turn the ignition switch OFF.

1. Disconnect the MAP sensor 3P connector.

1. Check the MAP with the scan tool.

Is about 250 kPa (1,877 mmHg, 73 in. Hg) indicated?

YES – Go to step 10.

NO – Substitute a known-good ECM and recheck. If symptom/indication goes away, replace the original ECM.

1. Check the MAP sensor signal and supply circuit for B+ short.

Is a problem found?

YES – Repair open in the signal wire or supply wire between ECM and the MAP sensor.

NO – Substitute a known-good ECM and recheck. If symptom/indication goes away, replace the original ECM.

NOTICE

The battery power supply short circuit to 5 V power supply damages the ECM.

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