Serial Data Circuit, Multiple Intermittent Codes: Notes
WARNING: This page is about a different car, the 1993 Buick Riviera and 1992 Buick Riviera. However, it is still accessible from the selected car via links, so may be relevant.
A damaged data line circuit or one of the components connected to the data line may cause multiple or intermittent setting of data line Codes B333, B334, B335, B336 and/or B337. When operating normally, serial data line voltage will continually fluctuate between .1 and 5.0 volts.
If serial data line has been shorted to ground, voltage at the ALDL will be zero volts. If it has been shorted to voltage, it will be greater than 5.0 volts. If one of the components on the serial data line is affecting the data line voltage, serial data voltage at the ALDL connector will be a steady value anywhere between .1 and 5.0 volts.