Series 50 – Section 17.2 Electronic Control Module Wiring Harness

Section 17.2
Electronic Control Module Wiring Harness

To determine if the electronic control module (ECM) wire harness is causing starting difficulty, perform the following:‪

1. Turn the ignition switch to the on position.
2. Install the Diagnostic Data Link (DDL) adaptor to the data cable and plug the adaptor into the DDL connector in the vehicle; refer to OEM guidelines.
3. Determine if ECM data is being received by the DDR; refer to OEM guidelines.
   1. If no data is being received by the DDR, check for intermittent code or a fault and no codes.
   2. If data is being received by the DDR, check vehicle circuit breakers or fuses; refer to "17.2.1 Vehicle Circuit Breakers or Fuses Check" .

Section 17.2.1
Vehicle Circuit Breakers or Fuses Check

To determine if the vehicle circuit breakers is causing starting difficulty, perform the following:‪

1. Visually check ECM circuit breakers or fuses and determine if circuit breaker(s) or fuse(s) are tripped or blown; refer to OEM guidelines.
   1. If circuit breakers are being shorted, determine cause and repair or replace as necessary; refer to OEM guidelines.
   2. If circuit breakers are not being shorted, measure the voltage at the ECM power harness; refer to "17.2.2 ECM Power Harness Voltage Test" .

Section 17.2.2
ECM Power Harness Voltage Test

To determine if the electronic control module power harness is causing circuit breakers to be tripped or blown, perform the following:‪

1. Turn ignition off, if required.
2. Disconnect the 5-way power harness connector, see Figure "5-Way ECM Power Connector" .
   

   Figure 1. 5-Way ECM Power Connector

3. Measure and record voltage from socket "A'' (red lead) of 5-way power harness connector to a good ground (black lead).
4. Measure and record voltage from socket "C'' (red lead) to a good ground (black lead).
5. Review the measured voltage readings.
   1. If the voltage measured is less than 10 volts, inspect and repair power harness; refer to "17.2.3 Power Harness Repair" .
   2. If the voltage measured is greater than 10 volts, check for low battery voltage; refer to "17.3 Low Battery Voltage" .

Section 17.2.3
Power Harness Repair

Perform the following steps to repair power harness:‪

1. To repair damage to the power harness; refer to "30.1 Lead Repair" .
2. Verify repair of the power harness; refer to "17.2.3.1 Test Engine with Repaired Power Harness" .

Section 17.2.3.1
Test Engine with Repaired Power Harness

Perform the following to determine if the repair resolved starter difficulty:‪

1. Attempt to start and run the engine.
   1. If the engine starts and runs, no further troubleshooting is required. Shut the engine down.
   2. If the engine fails to start and run, check for low battery voltage; refer to "17.3 Low Battery Voltage" .