For 1990-2009 cars only
Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P0A87: 14 Volt Power Module Current Sensor PerformanceCircuit/System Description
The auxiliary power module (APM) current sensor is used for over current limitation (less than 150 A). The starter/generator control module (SGCM) monitors the current sensor to detect the failure of the APM current sensor circuit (performance monitor).
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
APM current limit.
Action Taken When the DTC Sets
| • | Stop PWM (MGU shutdown). |
| • | APM PWM off. |
Conditions for Clearing the DTC
| • | APM current (IR 1) is restricted by maximum current (IR HI or IR LOW) |
| • | In case of Buck mode: IR 1 - IR HI is greater than 39 A for 25 ms. |
| • | In case of Boost mode: IR - IR LOW is greater than 39 A for 25 ms. |
| • | IR 1: APM current, IR HI: APM buck mode current limit +130 A. |
| • | IR LOW: APM boost mode current limit (-130 A). |
| • | APM output voltage (V14OUT) is greater than 7 volts and 42-volt output voltage (42OUT) is greater than 28 volts. |
| • | Clears 30 seconds after cycle wakeup signal. |
Diagnostic Aids
Possible internal failure at current sensor.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Starter/Generator Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- With a scan tool, clear the DTC.
- Ignition OFF, wait 30 seconds.
- Ignition ON, operate the vehicle within the Conditions for Running the DTC and verify the DTC does not reset.
| ⇒ | If the DTC resets, replace the SGCM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for SGCM replacement, setup, and programming.
