BobCat 753 – ALTERNATOR (90 AMP) – Charging System Check

If the charging system malfunctions check the following:

Check the condition and tension of the alternator belt.
(See Adjusting The Alternator Belt on Page 60-31-1.)
Replace the belt if it is worn or deteriorated.

Inspect the alternator wiring harness and connectors at alternator. Harness and connectors must be clean and tight.

Check the fuse for the alternator in the fuse panel. If fuse is burned, find the cause and repair/replace. If fuse is in
doubt, remove it and check for continuity.

Check the electrolyte level in the battery. Add distilled water as needed. (Does not apply to maintenance free batteries.)

Verify the charge of the battery. Make sure battery is fully charged.

Disconnect the battery cables (negative first, then positive). Inspect the cable clamps and battery posts for
corrosion. Remove acid or corrosion from the battery and cables with a sodium bicarbonate and water solution. Put
grease on the cable ends and battery terminals to prevent corrosion. Reconnect the cable to the positive terminal.

With the key off, connect a test light between the negative battery post and the disconnected negative cable clamp.

1. If the test light does not light up, reattach the clamp and proceed to alternator voltage test. (See Charging
System Check on Page 60-31-2.)

2. If the test light lights up, there is a short (drain) in the electrical system of the loader. The short must be repaired        before the charging system can be checked.

3. Disconnect the alternator B+ terminal (Item 1) and L & S terminal connector (Item 2) [Figure 60-31-4] and
if the test light goes out, the alternator is faulty. If the test light stays on, find the short in the system and repair it.


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