Diagnostic Instructions
DTC Descriptor
DTC P0A87: 14 Volt Power Module Current Sensor Performance
Circuit/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
Auxiliary Power Module (APM) current limit.
Action Taken When the DTC Sets
| • | Stop PWM (MGU shutdown). |
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
Hybrid Controls Schematics
Connector End View Reference
Hybrid Controls Connector End Views
Electrical Information Reference
Scan Tool Reference
Scan Tool Data List
Circuit/System Verification
Caution: To help avoid personal injury, additional precautions must be taken prior to working on the generator control module or the generator starter. After removing the 36V battery cables from the generator battery, remove both
engine wiring harness connectors from the generator control module. Wait at least 5 minutes and then remove the generator control module cover. Verify voltage levels at all 36V, 12V, and 3-phase connections, are less than 3 volts using
a DMM before proceeding.
- If DTC is history, refer to
Testing for Intermittent Conditions and Poor Connections
.
- If DTC is current, replace the SGCM.
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
Control Module References
for SGCM replacement, setup, and programming.
