Circuit Description
The Powertrain Control Module (PCM) monitors the system voltage on the ignition feed terminals to the PCM. A system voltage DTC sets whenever the voltage is below a calibrated value.
Conditions For Setting The DTC
| • | The system voltage is less than 10 V. |
| • | The RPM is greater than 1300 RPM. |
| • | The fault is present for 240 seconds. |
Action Taken When the DTC Sets
| • | The PCM records the operating conditions at the time the diagnostic fails. The Failure Records buffers stores this information. |
| • | A history DTC is stored. |
Conditions for Clearing the DTC
| • | A History DTC clears after 40 consecutive warm up cycles without a fault. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
Whenever a DTC sets when an accessory is operated, check for a poor connection or an excessive current draw.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
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This checks if the generator is malfunctioning under load conditions.
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PCM Controlled Generator Diagnosis will further check the PCMs control of the generator.
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Checks ignition positive voltage circuit #2 for excessive resistance. An open circuit will cause a no start condition.
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Replacement PCMs must be reprogrammed and the crankshaft position system variation procedure must be performed. Refer to the latest Isuzu Technical Communication System (ITCS) information for programming procedures and also refer to the Powertrain Control Module (PCM) .
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If no malfunctions have been found at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to | ||
Is the ignition voltage less than the specified value? | 1400 RPM 10 V | |||
Is the battery voltage greater than the specified value? | 1400 RPM 12V | Go to PCM Controlled Generator | ||
Is the ignition voltage greater than the specified value? | 10V | |||
5 | Check for a malfunctioning connection at the PCM harness terminals and repair as necessary. Was a repair necessary? | -- | ||
6 | Repair the poor connection (high resistance) in the ignition positive voltage circuit #2. Is the action complete? | -- | -- | |
Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||
8 |
Does the scan tool indicate that this diagnostic has ran and passed? | -- | ||
Check if any additional DTCs set. Are any DTCs displayed that have not been diagnosed? | -- | Go to applicable DTC table | System OK Refer to Diagnostic Aids |
