P0AFB
DTC P0AF8 or P0AFB
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0AF8
- Hybrid System Voltage
DTC P0AFB
- Hybrid Battery System Voltage High
Circuit/System Description
P0AF8
The engine control module (ECM) monitors the correlation of the battery energy control module (BECM) battery voltage and the starter generator control module (SGCM) output voltage to detect a 3 phase cable open or fuse/relay failure.
P0AFB
The ECM also monitors to detect an over voltage condition and protect the MOSFET (load dump).
If either one of these conditions is detected, the appropriate DTC will set.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
P0AF8
The 36-volt BECM battery voltage - 36-volt SGCM output voltage is greater than 5 volts for 4 seconds.
P0AFB
* In the hardware, 36-volt over voltage signal from protection circuit (sets above 56 volts, clears below 53 volts) is set for 20 ms.
* In the software, 36-volt output voltage is greater than 50 volts for 5 ms.
Action Taken When the DTC Sets
P0AF8, P0AFB
* Stop PWM (MGU shutdown)
* APM PWM off
Conditions for Clearing the DTC
P0AF8
36-volt voltage from BECM (42 VIN) is greater than 0 volt, main relay is closed, and 42 VIN invalid flag is ON.
P0AFB
* In the hardware, clears 30 seconds after wakeup signal is ON.
* In the software, voltage is normal for 100 ms and main relay is closed.
Diagnostic Aids
P0AF8
* Possible battery cable open
* Possible fuse/relay block electrical failure
* Possible 36-volt output or 36-volt battery sensor stuck
P0AFB
* Possible battery cable open (load dump)
* Possible fuse/relay block electrical failure
* Possible battery pack contactor open
Reference Information
Schematic Reference
* Hybrid Controls Schematics ()
* Hybrid Energy Storage Schematics ()
Connector End View Reference
Component Connector End Views (Connector Views)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning)for scan tool information
Circuit/System Testing
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.
Caution: To help avoid personal injury, be careful when working in the vicinity of the generator battery disconnect control module. Internal components will still be live, 36V potential, even when the cover has been opened or removed.
P0AF8
1. If DTC is history, refer to Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics).
2. Ignition ON, observe the scan tool Hybrid Battery System Voltage parameter in the BECM data list and the Hybrid System Voltage parameter in the SGCM data list. The voltage should not differ by more than 5 volts.
• If greater than the specified range, replace the BECM.
P0AFB
1. If DTC is history, refer to Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics).
2. Ignition ON, observe the scan tool Hybrid Battery System Voltage parameter in the BECM data list. The voltage should be less than 50 volts.
• If greater than the specified range, replace the SGCM.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
Control Module References (Programming and Relearning)for BECM/SGCM replacement, setup, and programming