CODE 75, SYSTEM VOLTAGE LOW GMC Suburban I

CODE 75, SYSTEM VOLTAGE LOW

Code 75 will set when ignition is on and control module 12-volt battery feed voltage is less than 9 volts for about 4 seconds. During time failure is present, force motor, also referred to as pressure control solenoid, is turned off, maintaining only 2nd gear and inhibiting TCC operation.

Note. Test numbers refer to numbers on diagnostic chart.

1. Checks for normal battery voltage.
2. Checks if low voltage display is due to generator, battery voltage input circuit or control module.

Charging battery with a charger and jump starting engine may set this code. If code sets when an accessory is operated, check for poor connections or excessive current draw. Also, check for poor connections at starter solenoid or fusible link. Minimum voltage allowed for Code 75 to set is on a graduated scale and changes with temperature from a low of 7.3 volts at -40°F (-40°C) to a voltage of 11.7 volts at 304°F (150°C).

Code 75 Schematic (All Models) System Voltage Low. Scheme 367

Code 75 Flow Chart (All Models) System Voltage Low. Scheme 368