W T E C I I I E L E C T R O N I C C O N T R O L S T R O U B L E S H O O T I N G M A N U A L
CODE 66 XX SCI (SERIAL COMMUNICATION INTERFACE) FAULT
Main code 69 indicates a problem which has been identified as being from within the ECU.
A cateye display or a blank display may occur with subcode 33.
Active Indicator Clearing Procedure:
Manual except subcodes 33, 35, 36, 41, 42, and 43
Self-clearing subcode 42 and subcodes 33, 35, 36, and 41; after an ECU reset
Subcode 34 cannot be cleared.
1. For subcodes 27, 28, and 29, check for shorts to battery before replacing the ECU. Follow the
troubleshooting steps for code 42 XX for checking shorts to battery. If no shorts are found, replace
the ECU. If replacing the ECU corrects the problem, reinstall the original (bad) ECU to confirm
that the problem is in the ECU. If the problem recurs, reinstall the new ECU to complete the repair.
2. For all other subcodes, replace the ECU.
ECU, Inoperative A-Hi switch
ECU, Inoperative F-Hi switch
ECU, Inoperative N-Hi and H-Hi switch
ECU, computer operating properly timeout
ECU, write timeout
ECU, RAM self-check failure
Communication chip addressing error
ECU, I/O ASIC addressing test
SPI output failure
SPI input failure