INDIVIDUAL CIRCUIT DESCRIPTION
The machines have a 3T8325 Electronic Service Meter. The meter gets its
power from the 10 amp fuse marked HR METER & START AID on the
fuse panel under the instrument panel. There is a normally open Start Protect
and Service Meter Relay that makes a ground for the meter. When the engine
is running and the alternator R terminal supplies +12V, the relay closes
and activates the service meter.
This service meter uses a solid-state (no moving parts) timing circuit that
sends a timing pulse (current for a short time) every 36 seconds to the solenoid
that moves the counter. When the engine is started and the meter first gets
power, it takes a minute or more for the first movement of the counter. The
meter works on a 24 volt negative ground system only.
The 3T8325 Electronic Service Meter has a very good service record. If
the meter does not work, make sure the PU wire has 24 volts and that the
LTGR wire is at ground. Most meter failures are really failures of the service
meter relay that makes the ground for the circuit, or of the wiring to the meter.
1. Service meter.