Circuit Description
The Integrated Radio Controller (IRC) keeps an EEPROM value that contains
a checksum for each of its EEPROM blocks. These values are not included in
the checksums of the blocks, but is a static, or read only value. The IRC
computes a checksum for the EEPROM block and compares it to a checksum stored
in the EEPROM. If the values do not match, then the IRC sets DTC B1658.
Conditions for Setting the DTC
| • | The stored checksum does not match the calculated checksum. |
| • | The IRC detects an intenal memory malfunction (checksum error). |
| • | The condition must occur when the ignition is first turned ON
or within 2.5 seconds of the ignition being turned ON. |
Action Taken When the DTC Sets
| • | DTC B1658 is stored in the IRC memory. |
| • | No driver warning message will be displayed for this DTC. |
| • | The IRC will use default values for any memory addres in the EEPROM
that is corrupt. |
Conditions for Clearing the DTC
| • | This DTC requires an ignition cycle in order to change from a
current DTC to a history DTC. |
| • | The IRC no longer detects an internal memory malfunction (checksum
error). |
| • | A history DTC will clear after 50 consecutive ignition cycles
if the condition for the malfunction is no longer present. |
Diagnostic Aids
| • | Since the EEPROM cannot be removed from the IRC and DTC B1658
is an internal IRC malfunction, the IRC needs to be replaced. |
