## Diesel Engine Management System

#### DTC Troubleshooting (cont'd)

11-128

1. Turn the ignition switch OFF.

1. Disconnect the redundant brake SW connector.

1. Check for open or short to ground in the redundant brake SW circuit wire.

Is a problem found?

YES – Repair open or short to ground in the redundant brake SW circuit wire.

NO – Go to step 18.

1. Replace the redundant brake SW.

1. Connect the ECM connector A.

Is there DTC P1550 being output?

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

NO – System is OK.

NOTICE

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

a a a