Circuit Description
The powertrain control module (PCM) uses the generator turn on signal circuit to control the load of the generator on the engine. A high side driver in the PCM applies a voltage to the voltage regulator. This signals the voltage regulator to turn the field circuit ON and OFF. When the PCM turns ON the high side driver, the voltage regulator turns ON the field circuit. When the PCM turns OFF the high side driver, the voltage regulator turns OFF the field circuit.
The PCM monitors the state of the generator turn on signal circuit. The PCM should detect a low generator turn ON signal circuit voltage when the key is ON and the engine is OFF, or when the charging system malfunctions. If the PCM detects a high generator turn ON signal circuit voltage, DTC B1488 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B1488 Generator L-Terminal Circuit High Voltage
Conditions for Running the DTC
| • | No generator, crankshaft position (CKP) sensors, or camshaft position (CMP) sensor DTCs are set. |
| • | The ignition is in the ON position |
| • | The engine is not running. |
Conditions for Setting the DTC
The PCM detects a high signal voltage on the generator turn on signal circuit for at least 5 seconds.
Action Taken When the DTC Sets
| • | The PCM will not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM will store the conditions present when the DTC set as Failure Records data only. |
| • | The PCM will send a class 2 serial data message to the instrument panel cluster (IPC) and driver information center (DIC) to illuminate the charge indicator or display a charging message. |
Conditions for Clearing the MIL/DTC
| • | The conditions for setting DTC B1488 are not present. |
| • | The DTC can be cleared by using the scan tool Clear DTC Information function. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Starting and Charging Schematics Connector End View Reference: Powertrain Control Module Connector End Views in Engine Controls - 2.4L (LD9) | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Charging System Check in Engine Electrical |
2 |
Does the scan tool indicate that DTC B1488 has passed this ignition cycle? | -- | Go to Intermittents and Poor Connections Diagnosis in Wiring Systems | Go to Step 3 |
3 |
Is the voltage within the specified range? | 4.5-5.5 V | Go to Step 5 | Go to Step 4 |
4 | Test the generator turn on signal circuit for a short to battery voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 8 | Go to Step 6 |
5 | Inspect for poor connections at the harness connector of the generator. Refer to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 8 | Go to Charging System Check |
6 | Inspect for poor connections at the harness connector of the powertrain control module (PCM). Refer to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 8 | Go to Step 7 |
7 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 2.4L and Powertrain Control Module Replacement/Programming in Engine Controls - 3.4L. Did you complete the replacement? | -- | Go to Step 8 | -- |
8 |
Does the scan tool indicate that DTC B1488 failed? | -- | Go to Step 2 | System OK |
