The following listed items should be checked prior to starting any troubleshooting:
- Ensure engine serial number on the ECM/ECU matches the serial number on the cylinder block.
- Walk around the vehicle. Look for obvious problems such as leaks (air or liquid).
- Inspect ECM/ECU for worn isolators, debris or bolts lodged between ECM/ECU and cylinder block.
- Broken wiring connectors.
- Fuel Supply - Full on.
- Fuel tank level.
- Vehicle damage.
- Investigate any prior repairs, if applicable.
- Check for poor mating of the connector halves or terminals not fully seated in the connector body (backed out terminals).
- Look for improperly formed or damaged terminals. All connector terminals in the problem circuit should be carefully inspected to determine proper contact tension. Use a mating terminal to test the contact tension.
- Electrical system interference caused by a defective relay, ECM/ECU driven solenoid, or a switch causing an electrical surge. Look for problems with the charging system (alternator, etc.). In certain cases, the problem can be made to occur when the faulty component is operated as in the case of a relay.
- Verify alternator grounds are clean and making good contact. Disconnect the alternator belt to test.
- Wiggle wires and harnesses to try to make the problem active, or re-occur.
The following label is attached to the ECM/ECU. See Figure "ECM/ECU Label" .
Figure 1. ECM/ECU Label
Every DDEC system engine serial number has its own file in the DDC Mainframe.
Failure to match the serial number on the engine with the ECM/ECU programming may result in incorrect calibration results and engine damage.
ECM/ECU programming must be done to match the serial number you are currently working on. Failure to do so may result in incorrect calibration and engine damage.
Programming a DDEC V ECM/ECU must be done with an engine file set up for the DDEC V system.
Ask the driver to answer the following questions before attempting to repair an intermittent problem, or a problem with symptoms but no diagnostic codes. Be specific! Use this and the response guideline to these questions.
- How often does the problem occur? Can you and the driver take the vehicle and demonstrate the problem in a short time?
- Has the vehicle been to other shops for the same problem? If so, what was done there?
- Did the radio, dash gages, or lights momentarily turn OFF when the problem occurred?
- Does the problem occur only at specific operating conditions? If so, at what load? Is it light, medium, or heavy?
- Does the problem occur at a specific engine operating temperature? If so, at what engine temperature?
- Does the problem occur only when above or below specific outside temperatures? In what temperature range?
- Does the problem occur during other conditions e.g. during or after rain, spray washing, snow?
- Did the problem occur at a specific vehicle speed? If so, at what vehicle speed?
- Does the problem occur at specific engine rpm? If so, at what engine rpm?
Questionnaire Response Guideline
The following are typical responses to the Driver Questionnaire:
- If the problem is repeatable, take the vehicle for a drive with the DDR connected and note the conditions when the problem occurs. Be prepared to take snapshot data using the DDR. Ensure you operate the vehicle after correcting the problem and duplicate the operating conditions before releasing the unit, to verify the problem is corrected.
- If the vehicle has been to other shops for the same problem, call the other shops and find out what has been done. Avoid replacing the same components again unless absolutely sure they are the problem! It is unlikely a component will fail again following a recent replacement.
- If other vehicle devices are affected, this indicates there may be something wrong with the ignition wiring. Refer to "80.1 Troubleshooting the Vehicle Interface Harness +5 Volt Supply" for information on inspecting the ECM/ECU battery connections.
- Operate the engine under similar load conditions. Check the fuel system for restrictions, primary filter, and fuel tanks for foreign objects blocking the fuel supply. Also, check the air system. Utilize the DDR snapshot feature.
- Operate the engine at this temperature while attempting to duplicate the problem. Use the snapshot feature on the DDR.
- If possible, troubleshoot the problem in this temperature range.
- If the problem seems to occur during or after the engine is subjected to rain/spray washing, thoroughly inspect the connectors for moisture entry.
- If the problem occurs at a specific vehicle speed, check the parameters affecting vehicle speed to verify they are programmed close to the vehicle speed where the problem occurs. Check Vehicle Speed and watch the DDR (snapshot) for changes to see if the pulse wheel (VSS signal) is loose.
- If the problem occurs at a specific engine rpm, unplug the oil, coolant, and air temperature sensors, and note any changes to the problem. Gather this data and contact Detroit Diesel Customer Support Center (313-592-5800).
Before Troubleshooting the Electronic Controls
The following items must be read and thoroughly understood before using this manual.
- The engine and ignition should always be off before the harness connectors are disconnected or reconnected.
- When disconnecting harness connectors, ensure the pulling force is applied to the connectors themselves and not the wires extending from them.
To avoid damage to the harness connectors, ensure the pulling force is applied to the connections themselves and not the wires extending from them.
- After harness connectors are reconnected to the DDEC system, the codes logged should be ignored and cleared.
- In most all areas of repair/troubleshooting, a DDR will be required.
- In diagnosing an intermittent problem, wiggling wires or harnesses may allow the fault to be repeated. This may allow a technician to better isolate the problem area.
|Series 60 DDEC V Troubleshooting Guide - 6SE570|
|Generated on 10-13-2008|