MBE 900 DDEC VI Troubleshooting – Section 4.1 Poor Vehicle Ground

Section 4.1
Poor Vehicle Ground

To determine if poor vehicle ground is causing the cylinder to misfire, perform the following steps:‪

1. Remove the alternator drive belt, refer to the MBE 900 Service Manual (6SE9007), electrical equipment chapter-drive belts.

   PERSONAL INJURY ‪
   To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked.‪

2. Start the engine.
3. Run the engine through operating range.
4. Listen for engine misfiring.
   1. If the engine is not misfiring, refer to "4.1.1 Negative Lead Repair" . Shut down the engine.
   2. If the engine is still misfiring, check for aerated fuel; refer to "4.2 Aerated Fuel" .

Section 4.1.1
Negative Lead Repair

Perform the following steps for negative lead repair:‪

1. Shut down the engine.
2. Remove negative lead(s) at frame ground stud near battery box.
3. Clean ground stud; refer to OEM guidelines.
4. Clean negative lead(s) terminal lugs with low grit sandpaper.
5. Repair any loose or damaged lead(s), using the splice method or rosin core solder.
6. Install negative lead(s) to frame ground stud; refer to OEM guidelines.
7. Install alternator drive belt, refer to the MBE 900 Service Manual (6SE9007), electrical equipment chapter-drive belts.

   Note: Drive belts (Vee and poly–vee) should be replaced every 2,000 hours or 160,000 km (100,000 miles).

8. Verify negative lead repair; refer to "4.1.1.1 Verification of Repair for Negative Lead" .

Section 4.1.1.1
Verification of Repair for Negative Lead

Perform the following steps to determine if negative lead repair resolved the misfiring cylinder condition:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked.‪

1. Start the engine.
2. Run engine speed up to the occurrence of the misfiring.
3. Listen for misfiring cylinder.
   1. If the engine is not misfiring, no further troubleshooting is required. Shut down the engine.
   2. If the engine is misfiring, check for aerated fuel. Shut down the engine; refer to "4.2 Aerated Fuel" .