Diagnostic Aids

Check circuit No. 496 for a potential short or open to ground. Also check for proper installation of MEM-CAL. Mechanical engine knock can cause a knock sensor signal. Abnormal engine noise must be corrected before using this chart.

NOTE: Code 43 shematic/circuit diagram and flow chart have been updated by the following Technical Service Bulletin Nos. dated 8/24/90:

Bulletin No. 91-6E-01 for Buick models.
Bulletin No. 91-64-6E for Chevrolet models.
Bulletin No. 91-T-07 for Oldsmboile models.
Bulletin No. 91-6-6 for Pontiac models.

Fig 1: Code 43, Schematic, ESC Error Without ESC Module See Note Aove in Text

Fig 2: Code 43 Flow Chart, ESC Error Without ESC Module See Note Above in Text