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 you turn ON the ignition, the module performs internal tests on the EEPROM. The test may determine the integrity of the non-volatile memory. The module compares the previously stored checksum with a checksum calculated when the ignition turns ON. If the 2 checksums do not match, the module will indicate that a calibration malfunction is current.
Conditions for Setting the DTC
| • | The stored checksum does not match the calculated checksum. |
| • | The module detects an internal memory malfunction. |
| • | The condition occurs when the ignition is first turned ON. |
Conditions for Running the DTC
The module runs the program to detect a write error whenever it writes to the EEPROM. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.
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 with out 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 for the system exhibiting the symptom? | Go to Step 2 | Go to Control Module References for the applicable Diagnostic System Check |
2 |
Is the DTC retrieved as a current DTC? | Go to Step 3 | Go to Diagnostic Aids |
3 |
Important: Perform the programming or setup procedure for the module if required. Replace the control module setting the DTC as current. Refer to Control Module References . Did you complete the replacement? | Go to Step 4 | -- |
4 |
Does the DTC reset? | Go to Step 2 | System OK |
