Diagnosis - Isuzu C22NE Workshop Manual

6D3-12 STARTING AND CHARGING SYSTEM

Diagnosis

The EP regulator incorporates diagnostics which will illuminate
the warning lamp as a result of fault conditions in the generator
and external circuitry.
These conditions include:
1. An open circujit in the regulator battery sensing wire (S
Terninal)
2. An open circuit or excessive voltage drop in the B+ cable.
3. An open circuit in the generator phase connection.
4. Overcharging of the battery.
5. Regulator output stage short circuit.
6. Open circuit rotor.
The regulator compares the voltage at B+ with the voltage at
the "S" terminal connceted to battery positive. If the voltage
differential exceeds a predetermined threshold, the regulator
will operate in backup mode to limit the output voltage to a safe
level. The warning lamp; will remain illuminated as along as
these conditions prevail.
Sources of high resistance which will trigger the warning lamp
are:
a. Poor contact in wiring harness connectors.
b. Poor contact between rectifier and regulator.
c. High resistance in fusible link assembly.
Caution:
When bench testing the generator it is important that the
warning lamp wattage of 2 watts is not exceeded.
Reversal of the "S" and "L" on the regulator will damage
the regulator.
The correct plug for the regulator is a 9 122 067 011 for the
Bosch tye and for the Shinagawa connector the number is
X02FW.
See appendix 1 for daignostic matrix.
Before testing or disassembling the generator please observe
the following points.
1. When testing the diodes with AC type testers the RMS.
Vlotage output must not exceed 12.0 volts, it is
recommended that the stator should be disconnected
during this test.
2. Where zener power diodes are used, the breakdown
voltage should be tested to ensure all diodes have the same
zener voltage.
3. Insulation tests on the rotor and stator should use a voltage
not exceeding 110v for a series test lamp. The rectifier
must be disconnected from the stator prior to testing.
4. When carrying out repairs to the charging system always
disconnected the battery negative first, and reconnect it last.