Operator Information - Detroit Diesel MBE 900 Technician Manual

PRELIMINARY
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OPERATOR INFORMATION

This section should serve as a guideline for the technician. Talk to the operator/driver. Be specific!
DRIVER QUESTIONNAIRE
Ask the driver to answer the following questions before attempting to repair an intermittent
concern, or a concern with symptoms but no diagnostic codes. Use their responses to these
general questions as a guideline:
1. How often does the concern occur? (Can the driver operate the vehicle and demonstrate
the concern to you in less than 30 minutes? If the concern is repeatable, take the vehicle
for a drive with the Detroit Diesel Diagnostic Link (DDDL) connected. Start the snapshot
at the beginning of the road test, use the mark user event space to track problems, and
end the snapshot at the conclusion of the road test. Ensure you can operate the vehicle
after correcting the concern without duplicating the symptoms at the operating conditions
before releasing the unit to verify the concern is corrected.)
2. Has the vehicle been to other shops for the same concern? (If so, call the other shops
and find out what has been done. Avoid replacing the same components again unless
absolutely sure they are the source of the concern. It is unlikely the same component will
fail again following a recent replacement.)
3. Did the radio, dash gages, or lights momentarily turn OFF when the concern occurred?
(If other vehicle devices are affected, this indicates there may be something wrong with
the ignition wiring.)
4. Does the concern occur only at specific operating conditions? (Operate the engine under
similar load conditions.)
5. Does the concern occur at a specific engine operating temperature? (Operate the engine
at this temperature while attempting to duplicate the concern. Use the snapshot feature
on the DDDL.)
6. Does the concern occur at a specific engine operating altitude? (If possible, troubleshoot
the concern at this altitude.)
7. Does the concern occur only when above or below specific outside temperatures? (If
possible, troubleshoot the concern in this temperature range.)
8. Does the concern occur during other conditions, e.g. during or after rain, spray washing,
or snow? (If so, thoroughly inspect the connectors for moisture entry.)
9. Did the concern occur at a specific vehicle speed? (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 DDDL {snapshot} for changes to see if the pulse wheel [Vehicle Speed Sensor
{VSS} signal] is loose.)
10. Does the concern occur at a specific engine rpm? (If the concern occurs at a specific
engine rpm, unplug the oil, coolant, and air temperature sensors, and note any changes to
the concern. Gather this data and contact the Detroit Diesel Customer Support Center
at 313-592-5800.)
All information subject to change without notice. (Rev. 5/05)
7SE940 0505 Copyright © 2005 DETROIT DIESEL CORPORATION
MBE EGR TECHNICIAN'S GUIDE
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