Equus 3123 - GM Code Reader (1982 - 1995) - Manual (Page 21)

Retrieving ECM Codes
GM 2-12
CODE SERVICE CODE DEFINITION
68 On-board cruise control switch circuit problems Servo
Position Sensor (SPS) circuit fault or shorted A/C clutch
relay circuit (Corvette) or overdrive ratio error
69 Air conditioning head pressure switch circuit fault or air
conditioning pressure switch problem
Torque converter clutch stuck "on"
70 Air conditioning refrigerant pressure sensor circuit fault
(high pressure) or quad driver module error
71 Air conditioning evaporator temperature sensor circuit
fault (low temp.)
72 Gear select switch circuit fault - Corvette only
Vehicle Speed Sensor (VSS) - loss of signal
73 Air conditioning evaporator temperature sensor circuit
fault (high temp.)
(Transmission) Pressure control solenoid - circuit
problems
74 Traction control circuit voltage low
75 Digital EGR fault - #1 solenoid or system voltage low
(charging system problem)
Transmission voltage low
76 Digital EGR fault - #2 solenoid
77 Digital EGR fault - #3 solenoid
Primary cooling fan relay driver circuit - circuit
problems
78 Secondary cooling fan relay driver circuit - circuit
problems
79 Vehicle Speed Sensor (VSS) - signal voltage too high
Transmission Temperature Sensor (TTS) - high
temperature
80 Vehicle Speed Sensor (VSS) - signal voltage too low;
transmission component fault
81 QDM Solenoid "B" monitored voltage differs from
commanded
Anti-Lock Brake System (ABS) message fault (Saturn)
Brake switch circuit problems