## Diesel Engine Management System

#### DTC Troubleshooting (cont'd)

11-129

DTC P1551: Brake SW Signal Correlation Error

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. Turn the ignition switch OFF.

1. Check the brake lamp (10A) fuse.

Is the brake lamp fuse OK?

YES – Go to step 4.

NO – Replace the fuse.

1. Disconnect the ECM connector A.

1. Turn the ignition switch ON (II).

1. Connect the DVM to the ECM terminal No. 59 and body ground.

1. Press the brake pedal.

Is there battery voltage?

YES – Go to step 15.

NO – Go to step 8.

1. Turn the ignition switch OFF.

1. Disconnect the brake SW connector.

1. Connect the DVM to the brake SW connector terminal No. 1 and No. 2 with a jumper wire.

JUMPER WIRE

Wire side of female terminals

1. Turn the ignition switch ON (II).

1. Connect the DVM to the ECM terminal No. 59 and body ground.

1. Press the brake pedal.

Is there battery voltage?

YES – Replace the brake SW.

NO – Go to step 14.

1. Measure voltage between the brake SW connector terminals No. 1 and body ground.

Wire side of female terminals

Is there battery voltage?

YES – Repair open in the wire between the brake SW and the ECM.

NO – Repair open in the wire between the brake SW and the battery.

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