HOLDEN GEN III V8, Service Training

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GEN III V8 ENGINE MANAGEMENT
PCM Five Volt Reference Circuits
The PCM has two five volt reference circuits The five volt reference circuit number one supplies five volts to the
following sensors
• The Throttle Position Sensor (J1 -08)
• The Manifold Absolute Pressure Sensor (J1-48)
• Oil Pressure Sensor (J1-07)
The five volt reference circuit number two supplies five volts to the following sensor
• The A/C Pressure Sensor (J1-45)
The PCM monitors the voltage on the 5 0 volt reference circuit This DTC sets if the voltage is out of range
A failure in a Five Volt Reference Circuits will set one of the following DTCs:
DTC P1635 Five Volt Reference #1 Circuit
Conditions for running DTC P1635
• The ignition is on
Conditions for setting DTC P1635
• The five volt reference #1 circuit is out of range
• All of the above conditions are present for greater than 2 seconds
Action taken when DTC P1635 Sets
• The PCM illuminates the Check Powertrain Lamp when the diagnostic runs and fails
• The PCM records the operating conditions at the time the diagnostic fails The PCM stores this information
in the Freeze Frame/Failure Records
Conditions for clearing the Check Powertrain Lamp and DTC P1635
• The PCM turns the Check Powertrain Lamp OFF after one ignition cycle that the diagnostic runs and does
not fail
• A last test failed (Current DTC) clears when the diagnostic runs and does not fail
DTC P1639 Five Volt Reference #2 Circuit
Conditions for running DTC P1639
• The ignition is on
Conditions for setting DTC P1639
• The five volt reference #2 circuit is out of range
• All of the above conditions are present for greater than 2 seconds
Action taken when DTC P1639 Sets
• The PCM illuminates the Check Powertrain Lamp when the diagnostic runs and fails
• The PCM records the operating conditions at the time the diagnostic fails The PCM stores this information
in the Freeze Frame/Failure Records
Conditions for clearing the Check Powertrain Lamp and DTC P1639
• The PCM turns the Check Powertrain Lamp OFF after one ignition cycle that the diagnostic runs and does
not fail
• A last test failed (Current DTC) clears when the diagnostic runs and does not fail
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