freightliner M2 Plus Maintenance Manual page 37

Alternators and Starters
15–00 Safety Precautions
Safety Precautions in this section apply to all
procedures within this group.
DANGER
When working on the vehicle, shut down the
engine or motor, set the parking brake, and chock
the tires. Before working under the vehicle, always
place jack stands under the frame rails to ensure
the vehicle cannot drop. Failure to follow these
steps could result in serious personal injury or
death.
15–01 Alternator, Battery, and
Starter Checking
WARNING
Batteries release explosive gas as a by-product of
their chemical activity. Do not smoke when
working around batteries. Put out all flames and
remove any source of sparks or intense heat.
Make sure the battery compartment is completely
vented before disconnecting or connecting the
battery cables.
Battery acid is extremely harmful if splashed in
the eyes or on the skin. Always wear a face shield
and protective clothing when working around
batteries.
Damaged, chafed, or kinked wiring can cause
electrical short-circuits and lead to fires, causing
property damage, injury, or death. Clean, inspect,
and maintain wiring and connections carefully.
1. Disconnect the batteries.
2. Check the tightness of the alternator bracket
fasteners; tighten the fasteners as needed. For
torque values, see Group 15 of the Business
Class® M2 Plus Workshop Manual.
3. See Group 01 for belt tension specifications.
Check the alternator drive belt tension, using a
tension gauge at the belt's longest span. Some
engines are equipped with more than one
alternator belt; check all of them for correct
tension. Adjust the belt tension if necessary.
Business Class M2 Plus Maintenance Manual, 02/10/2023
Engines equipped with a serpentine or poly-V
belt have automatic belt tensioners, and do not
require belt tension inspection.
4. Check that all electrical connections at the
alternator and starter are clean. Clean and
tighten all charging system electrical connections
including the connections at the starter B
terminal and ground terminal, and where the
alternator charging cable terminates.
Trace and inspect all wiring and cables
connected to:
• alternator
• starter and depopulation studs
• batteries
• magnetic switch
• cab
• jump-start studs
• battery isolation relays
• battery shutoff switches
5. Check wires and cables for wear, chafing, kinks,
discolored insulation, or loose clamps or ties.
Find the cause of any problems and repair,
replace, and reroute wires and clamps as
necessary.
6. Check the alternator wiring for missing insulation,
kinks, and heat damage. Replace or repair as
needed.
7. On the bundled cable that runs from the batteries
to the starter, ensure that tie straps are installed
at least every 12 inches (300 mm). Replace any
missing tie straps, and add tie straps where
spacing between them exceeds 12 inches (300
mm).
8. Ensure that all cables have sufficient slack to
allow for engine movement, and that there is no
pressure on any wiring connectors.
9. If any convoluted tubing is damaged, check the
wiring inside it. Replace any damaged or missing
convoluted tubing.
10. Clean the cable connector terminals with a wire
brush. See Group 54 of the Business Class M2
Plus Workshop Manual for troubleshooting
instructions, and for adjustment, repair, or
replacement instructions.
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