1999 PCED On Board Diagnostics II |
SECTION 5: Pinpoint Tests |
HY1 DTC P1246: VERIFY GENERATOR DRIVE FUNCTION
- Check generator drive belt condition.
- Check generator drive belt tension.
- Start engine, verify generator turning.
Does generator turn?
|
Yes
|
No
|
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GO to HY2
.
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GO to Charging System Section 414-00 in the Workshop Manual.
|
HY2 VERIFY CHARGING SYSTEM IS EEC CONTROLLED
- Key off.
- Disconnect battery terminals at battery.
- Disconnect cable at generator B+ terminal.
- Disconnect generator harness connector and measure resistance between
battery-sense and gen-com pin at the generator.
Is resistance between 950 and 1050 ohms?
|
Yes
|
No
|
|
GO to HY3
.
|
REPLACE generator/regulator assembly. Verify that the
vehicle is charging properly after generator/regulator replacement,
if not GO to HY3
.
|
HY3 CHECK BATTERY-SENSE VOLTAGE AT BATTERY
- Reconnect generator.
- Reconnect battery.
Is battery voltage at battery-sense circuit pin at the
generator/regulator harness connector within plus or minus 0.5 volt of battery
voltage?
|
Yes
|
No
|
|
GO to HY4
.
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REPAIR battery-sense circuit.
|
HY4 CHECK GENERATOR FAILURE MODE
- All electrical load off.
- NGS connected.
- Access the AFSF PID.
- Increase engine speed to 2,000 rpm.
- Perform wiggle test.
Is a failure indicated?
|
Yes
|
No
|
|
GO to HY5
.
|
GO to Charging System, Section 414-00 in the Workshop Manual.
|
HY5 CHECK GEN-MON AND GEN-COM CIRCUIT FOR SHORT TO POWER
- Key off.
- PCM and generator/regulator disconnected.
- Key on.
- Measure voltage between gen-com signal pin at the PCM harness connector
and chassis ground.
- Measure voltage between gen-mon signal pin at the PCM harness connector
and chassis ground.
Is each voltage greater than 0.5 volt?
|
Yes
|
No
|
|
KEY OFF. REPAIR short circuit.
|
KEY OFF. GO to HY6
.
|
HY6 CHECK GEN-MON AND GEN-COM CIRCUIT FOR SHORT TO GROUND
- Measure resistance between the gen-com signal pin at the PCM harness
connector and chassis ground.
- Measure resistance between the gen-mon signal pin at the PCM harness
connector and chassis ground.
Is resistance greater than 10,000 ohms?
|
Yes
|
No
|
|
GO to HY7
.
|
REPAIR short circuit.
|
HY7 CHECK GEN-MON AND GEN-COM CIRCUIT FOR OPEN
- Measure resistance of the gen-com circuit between the
generator/regulator harness connector and the PCM harness connector.
- Measure resistance of the gen-mon circuit between the
generator/regulator connector and the PCM harness connector.
Is each resistance less than 5.0 ohms?
|
Yes
|
No
|
|
GO to HY8
.
|
REPAIR open circuit.
|
HY8 CHECK GENERATOR MONITOR SIGNAL
Is frequency between 100-175 Hz, and the duty cycle between 6-98%?
|
Yes
|
No
|
|
GO to HY9
.
|
REPLACE generator.
|
HY9 CHECK GENERATOR COMMUNICATOR SIGNAL
- Toggle load on and off. (headlights)
Did frequency signal switch between 0 and (100-175 Hz) and duty cycle
switch between 1-99%?
|
Yes
|
No
|
|
Generator function is OK. GO to Pinpoint Test Z
intermittent circuit failure diagnosis.
|
REPLACE PCM (refer to Section 2
, Flash EEPROM).
|
HY: Introduction