For 1990-2009 cars

### Circuit Description

The generator battery control module controls the generator through the generator turn on signal circuit. The signal is a 5-volt pulse width modulation (PWM) signal of 128 Hz with a duty cycle of 0-100 percent. Normal duty cycle is between 5-95 percent. If the generator turn on signal circuit is 65 percent or greater duty cycle or pulled high to battery positive voltage, 5 volts, then DTC B1488 will set.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1488 Generator L-Terminal Circuit High

### Conditions for Running the DTC

• | Vehicle in RUN mode and Engine Run Flag is False.

• | The engine RPM is less than or equal to 0 RPM.

• | This diagnostic shall be run every 100 ms.

### Conditions for Setting the DTC

The generator turn on signal circuit is 65 percent or greater and shorted high to battery voltage, 5 volts, for greater than 5 seconds.

### Action Taken When the DTC Sets

The generator battery control module will request the driver information center (DIC) message of Service Charging System and commands ON the Battery indicator.

### Conditions for Clearing the DTC

The generator battery control module determines the fault has cleared.

### Diagnostic Aids

Important: You must cycle the ignition after clearing the DTC to turn OFF the DIC message of Service Charging System.

Recommended Action:

• | Correct L-Term short high condition.

• | Clear the codes.

• | Cycle the ignition.

Important: You must cycle the ignition after clearing the DTC to turn OFF the DIC message of Service Charging System and turn OFF the battery indicator.

If a fault condition persists, replace the module.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Starting and Charging Schematics Connector End View Reference: Engine Electrical Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Ignition ON, engine OFF.
2. With a DMM, test the generator turn on signal circuit of the generator battery control module.

Is the DMM reading equal to or above the specified value?

4.8 - 5.2 V

Go to Step 4

Go to Step 3

3 | Inspect for poor connections at the harness connector of the generator battery control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 6 | Go to Step 5
4 | Repair the short to battery of the generator turn on signal circuit. Did you find and correct the condition? | -- | Go to Step 6 | Go to Step 5
5 | Replace the generator battery control module. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 6 | --
6 |

1. Use the scan tool in order to clear the DTC.
2. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK