GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The closed loop principle makes use of a zero-field detector signal which is processed to drive a current through a compensation coil in such a way, that it balances out the magnetic field of the applied current at any time. Thus the compensation current is proportional to the current to be measured. In contrast to common Hall-detectors the patented soft magnetic VAC-probe made from a small strip of amorphous metal VITROVACâ„¢ is strictly symmetric with respect to the magnetic field. Therefore it generates no offset contribution to the sensor. Moreover, the symmetry is neither affected by temperature changes or any aging effects. This enables for very high accuracy, nearly zero offset, and excellent stability over temperature and time.

In current sensors based on the closed loop principle the primary current conductor is lead through a magnetic core. The magnetic field of the primary current is concentrated in the magnetic core is detected by a soft-magnetic field probe in an air gap of the core. By means of a current through an additional winding on the core, the magnetic flux of the primary current is compensated. The magnetic flux in the core is held at zero value. The compensation current is proportional, and is an image of the primary current.

The current sensors are based on the closed-loop principle. A soft-magnetic probe is used as field detector of the primary current magnetic field. Compared to standard sensors with Hall-probes, the magnetic probe offers the following application advantages:

    • Low offset currents
    • Small temperature dependence
    • No long term drift of offset current
    • Small offset current forces
    • Compact size
    • Separate electronics available

Conditions for Running the DTC

    • Engine is running for 30 seconds.
    • The starter/generator control module (SGCM) has received voltage on the ignition 0 voltage circuit.
    • The SGCM has turned ON and no configuration DTC is present.
    • This diagnostic shall run every 100 milliseconds.
    • Reference voltage is stable and accurate.

Conditions for Setting the DTC

    • Exceeded performance range of a calculated value within the current sensor.
    • This diagnostic will be tested once every second.
    • P1A4A - Hybrid Battery Current Sensor Performance
    • P1A4B - Hybrid Battery Current Sensor Performance

Action Taken When the DTC Sets

    • The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC

    • A current DTC Last Test Failed clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
    • Clear the DTC with a scan tool.

Step

Action

Yes

No

Schematic Reference: Starting and Charging Schematics

Connector End View Reference: Engine Electrical Connector End Views

1

Was the Engine Electrical Diagnostic System Check performed?

Go to Step 2

Go to Diagnostic System Check - Engine Electrical

2

  1. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
  2. With a scan tool observe the ESCM DTC list.

Is the DTC set as current DTC?

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

3

Inspect for poor connections at the harness connector of the current sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 5

Go to Step 4

4

Replace the current sensor. Refer to High Current Battery Temperature Sensor Replacement .

Did you complete the replacement?

Go to Step 5

--

5

  1. Use the scan tool in order to clear the DTCs .
  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