Circuit Description
Running Reset
The on-board software watchdog timer shall cause a reset in the case that the timer is not refreshed within the time-out period.
EEPROM Checksum
When the checksum of data stored in electrically erasable programmable read-only memory (EEPROM) is not equal to the checksum stored in EEPROM at power down. This diagnostic shall be run once per second.
Loop Time Overrun
Two consecutive loop time overruns shall cause the fatal error handling routine to be called and this diagnostic to be set. This diagnostic shall be run once per second.
Module Configuration Refresh
This function shall check all of the program registers for each of the configured devices and, upon finding a discrepancy, reset them to their proper values and set this fault.
Module EEPROM Malfunction
If it can be determined where the bad EEPROM is, any processes that use that data shall be marked as invalid. If it can not be determined which part is bad, all data shall be set to invalid. This diagnostic shall be run after every write on the data being written.
Random Access Memory (RAM) Fault
The purpose of this test is to check the functionality of the energy storage control module (ESCM) volatile memory by performing a nondestructive read/write test. The current contents of the memory being checked shall be saved in a known correctly functioning alternate memory location. A set of 2 patterns will then be written to the memory under test. The contents of the memory under test shall be read and compared to the expected value. If the read value and the expected value do not match, the random access memory (RAM) fault shall be set .
Read Only Memory (ROM) Fault
The validity of the contents of non-volatile memory must be constantly checked for validity once the controller is initialized. This is a critical fault, when this fault is detected the controller will be held in a tight loop, causing the controller to be reset due to a watchdog time-out. The controller shall be held in this tight loop until the ignition is cycled OFF. Once the ignition is turned back ON, the controller shall begin in its power up state again. The entire read only memory (ROM) shall be tested at least every second. This test can be accomplished by comparing the run time calculated checksum of a predefined memory region with the expected checksum value which is stored outside the predefined memory region in ROM If the calculated value does not match the expected value.
Reference Range Voltage
When one or both of the reference range voltages are out of range, this diagnostic shall be run at least every second.
Battery Energy Control Module Hybrid System Voltage
The battery energy control module (BECM) is also referred to as the ESCM. This is a voltage calibration fault. When the correlation voltage is not within limits between the pack voltage and the bus voltage. This diagnostic shall be every 50 ms.
Stack Overrun
This is a critical fault. When this fault is detected, the controller will be held in a tight loop, causing the controller to be reset due to a watchdog time-out. The controller shall be held in this tight loop until the ignition is cycled OFF. Once the ignition is turned back ON, the controller shall begin in its power up state again. This diagnostic shall be run once per second.
The following DTCs are for internal failures within the ESCM:
| • | P1A00 - ESCM Reset |
| • | P1A01 - ESCM Long Term Memory Performance |
| • | P1A02 - ESCM Loop Overrun |
| • | P1A03 - ESCM Options Incorrect |
| • | P1A04 - ESCM Programming Read Only Memory (ROM) |
| • | P1A05 - ESCM Random Access Memory (RAM) |
| • | P1A06 - ESCM Read Only Memory (ROM) |
| • | P1A07 - ESCM 5-volt Reference Circuit |
| • | P1A08 - ESCM Stack Overrun |
| • | P1A09 - Battery Energy Control Module Hybrid System Voltage |
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
| • | This diagnostic will be tested once every second. |
| • | P1A00--The ESCM was abnormally reset during normal operation, Watchdog Timer, Stack Overflow, or Loss of Power. |
| • | P1A01--When the checksum of data stored in EEPROM is not equal to the checksum stored in EEPROM at power down. |
| • | P1A02--Critical Task Timing has not been met for 2 consecutive loops. |
| • | P1A03--Configuration registers of in/out (I/O) have contain different values than required. |
| • | P1A04--EEPROM malfunction was detected. |
| • | P1A05--RAM malfunction was detected. |
| • | P1A06--ROM malfunction was detected |
| • | P1A07--One or both of the reference range voltages are out of range. |
| • | P1A08--More bytes of the stack are used than are allocated. |
| • | P1A09 - Voltage correlation fault was detected. |
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 (DIC), 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. |
Diagnostic Aids
For the ESCM running reset fault P1A00, this can be caused if the 12-volt battery drops below 9 volts. If this DTC is set, check if there were any instances that the 12-volt battery could have gotten low or disconnected, and if so, ignore/clear this fault if it is in history.
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 | |
2 |
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 energy storage control module (ESCM). 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 ESCM. Refer to Generator Battery Control Module Replacement . Did you complete the replacement? | Go to Step 5 | -- |
5 |
Does the DTC reset? | Go to Step 2 | System OK |
