Electrical system
Checking the battery leads
Set the multimeter for voltage testing and then connect
the multimeter between the battery's plus and minus
pole. Run the engine at approx. 2000 rpm. Read off and
note the voltage over the battery poles.
The alternator provides approx. 14.0 V:
Conduct test as follows:
Connect the multimeter between the alternator's B+ and
B- connections.
Run the engine at approx. 2000 rpm. The alternator
should provide 14.0-14.4 V. The total voltage drop
must not exceed 0.4 V.
Voltage drop less than 0.2 V:
Battery leads in good condition.
Voltage drop more than 0.3 V:
Conduct check of battery leads.
The alternator provides more than 14.4 V:
See items "Checking and troubleshooting of alternator"
and "Checking of the regulator".
Checking of positive battery lead
Connect the multimeter between the alternator's B+
connection and the battery's plus pole.
Run the engine at approx. 2000 rpm. The voltage drop
must not exceed 0.2 V. If the voltage drop exceeds this
value the lead connections must be rectified as per the
"Procedure" below.
After this carry out a test as per "Checking of negative
battery charging".
Checking of negative battery lead
Connect the multimeter between the alternator's B-
connection and the battery's minus pole (-).
Run the engine at approx. 2000 rpm. The voltage drop
must not exceed 0.2 V. If the voltage drop exceeds this
value the lead connections must be rectified as per the
"Procedure" below.
74
Procedure
A
WARNING!
Disconnect the current and remove
both battery leads before working on the charging
circuit.
If the voltage drop during any of the tests as per the
i
tems above exceeds 0.2 V the lead connections must
be removed and cleaned from oxide etc. Spray the con-
nections with a moisture repellant contact oil (Volvo
Universal oil, part. No. 1161398-1) or the like and tight-
en the connection again.
Rectify the connections at the battery, main switch,
starter motor, alternator, glow relay and glow plug.
Alternator
Checking and troubleshooting of the al-
ternator
Dismantle the alternator's electrical connections.
Spanner widths 8 and 10 mm.
Remove the alternator belt. Dismantle the alternator.
Spanner widths 1 1/16"; 5/8"; 12 mm and 13 mm.
Release the voltage regulator's connections at the alter-
nator's B+ connection. Remove the flat pin at connec-
tion B+ and D+. Remove the cap on the W connection.
Bend the plastic guard's attachment lugs alternately off
the alternator. Release the regulator's two connection
cables to the diode bridge. Use long-nose pliers or poke
out the cable lugs with a screwdriver. Do not pull the
cables!
Replacement of carbon brushes in the
alternator
Unscrew the voltage regulator. Unscrew the brush hold-
er.
Check the length of the carbon brushes. Replace the
brushes if they are 5 mm (.1968 in) or shorter. Carbon
and holder are replaced as one unit. Unsolder the con-
nection cables and solder on the new ones with an
acid-free soft solder.
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