Check the following concerns prior to starting any troubleshooting:
- Ensure engine serial number on the DDEC Engine Control Unit (DDEC-ECU) matches the engine serial number.
- Walk around the vehicle and look for obvious problems such as leaks (air or liquid).
- Check the fuel filters to ensure they are secure and tight.
Note: The MBE 4000 has a water separator and a fuel filter. The MBE 900 has a prefilter and main filter.
- Check for a restricted air filter.
- Inspect truck frontal area for airflow restriction through the Charge Air Cooler (CAC) and radiator.
- Ensure that the fuel tank level is at least 1/4 full.
- Look for any vehicle damage that could affect vehicle performance or fuel economy.
- Investigate any prior repairs that could affect vehicle performance.
- Check for damaged mating of the connector halves or terminals not fully seated in the connector body (backed out terminals).
- Look for improperly formed or damaged terminals. Carefully inspect all connector terminals in the suspect circuit to determine proper contact tension. Use a mating terminal to test the contact tension.
- Check for electrical system interference caused by a defective relay, DDEC-ECU driven solenoid, or a switch causing an electrical surge. Look for concerns with the charging system (alternator, etc.). In certain cases, the concern can be made to occur when the faulty component is operated as in the case of a relay.
- Verify that alternator and battery grounds are clean and making good contact.
- Wiggle wires and harnesses to try to make the concern active, or reoccur.
|MBE 900 and MBE 4000 EGR Technician's Manual - 7SE940|
|Generated on 10-13-2008|