## Diesel Engine Management System

#### DTC Troubleshooting (cont'd)

11-98

DTC P1091: Rail Pressure (RP) Control Valve Circuit Open

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 DTCs (beside DTC) being output?

YES – Go to relevant chart.

NO – Go to step 3.

1. Check for the following conditions:

- Damaged the fuel metering unit.

Is a problem found?

YES – Repair as necessary (Replace the fuel supply pump).

NO – Go to step 4.

1. Turn the ignition switch OFF.

1. Disconnect ECM connector.

1. Check the fuel metering unit signal circuit for an open.

Wire side of female terminals

Injector 2P connector

JUMPER WIRE

Is a problem found?

YES – Repair the fuel metering unit circuit.

NO – Go to step 14.

1. Measure the resistance of fuel metering unit as below.

Is the resistance value 2.5 – 3.2 ohms? (At room temperature)

YES – Substitute a known-good ECM and recheck. If symptom/indication goes away, replace the original ECM.

NO – Replace the supply pump.

NOTICE

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

a a a