1995 GMC Forward Control 4.3 Z, AutomaticFACTORY OEM SERVICE PROCEDURE

Automatic Transmissions DTCS

AUTOMATIC TRANSMISSIONS DTCS

OEM Code Description
14 COOLANT TEMPERATURE SENSOR SIGNAL VOLTAGE LOW
14 ENGINE COOLANT TEMPERATURE (ECT) SENSOR CIRCUIT LOW (HIGH TEMPERATURE INDICATED)
15 COOLANT TEMPERATURE SENSOR SIGNAL VOLTAGE HIGH
15 ENGINE COOLANT TEMPERATURE (ECT) SENSOR CIRCUIT HIGH (LOW TEMPERATURE INDICATED)
21 TPS SIGNAL VOLTAGE HIGH
22 TPS SIGNAL VOLTAGE LOW
24 VEHICLE SPEED SENSOR CIRCUIT LOW (TRANS OUTPUT SPEED SIGNAL)
24 VEHICLE SPEED SENSOR TRANSMISSION OUTPUT SIGNAL
28 TRANS. RANGE PRESSURE SWITCH
28 TRANS. RANGE PRESSURE SWITCH CIRCUIT FAULT
39 TCC STUCK OFF
39 TCC STUCK OFF
52 SYSTEM VOLTAGE HIGH
53 SYSTEM VOLTAGE HIGH
58 TRANS. FLUID TEMP. HIGH
58 TRANS. FLUID TEMP. SENSOR CIRCUIT LOW (HIGH TEMPERATURE INDICATED)
59 TRANS. FLUID TEMP. LOW
59 TRANS. FLUID TEMP. SENSOR CIRCUIT HIGH (LOW TEMPERATURE INDICATED)
68 TRANSMISSION COMPONENT SLIPPING
68 TRANSMISSION COMPONENT SLIPPING
69 TORQUE CONVERTER CLUTCH STUCK ON
69 TORQUE CONVERTER CLUTCH STUCK ON
72 VEHICLE SPEED SENSOR CIRCUIT LOSS (TRANSMISSION OUTPUT SIGNAL)
72 VSS CIRCUIT LOSS TRANSMISSION OUTPUT SIGNAL
74 TRANS. INPUT SPEED ERROR
74 TRANS. INPUT SPEED ERROR
79 TRANS. FLUID TEMP. HIGH
79 TRANS. FLUID TEMP. HIGH
81 2-3 SHIFT SOLENOID CIRCUIT FAULT
82 1-2 SHIFT SOLENOID CIRCUIT FAULT
83 TCC PWM SOLENOID CIRCUIT FAULT
85 UNDEFINED GEAR RATIO
85 UNDEFINED GEAR RATIO
86 LOW GEAR RATIO ERROR
86 LOW GEAR RATIO ERROR
87 HIGH GEAR RATIO ERROR
87 HIGH GEAR RATIO ERROR
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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