Circuit Description
The electrically erasable programmable read only memory (EEPROM) write error detection is handled inside the control module. No external circuits are involved. The module calibrations are stored in EEPROM. When the ignition is turned on, the module performs internal tests on the EEPROM. The tests determine the integrity of the non-volatile memory when the ignition is turned ON. After 3 unsuccessful attempts at writing to the non-volatile memory, the module will indicate that a calibration malfunction error is current.
DTC Descriptors
This diagnostic procedure supports the following DTC:
DTC B1656 Electronic Control Unit (ECU) Performance
Conditions for Running the DTC
The module runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.
Conditions for Setting the DTC
The module detects an EEPROM checksum error.
Action Taken When the DTC Sets
The module finds another area to write the information to. This new area becomes the permanent area for storage of this information.
Conditions for Clearing the DTC
| • | A current DTC clears when the malfunction is no longer present. |
| • | A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction. |
Diagnostic Aids
| • | This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module. |
| • | If this DTC is retrieved as both a current and history DTC, replace the module. |
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Is DTC retrieved as a current DTC? | Go to Step 3 | Go to Diagnostic Aids |
3 | Replace the module setting the DTC as current. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | Go to Step 4 | -- |
4 |
Does the DTC reset? | Go to Step 2 | System OK |
