Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC1992MAGNAVAN 5.7 KREPAIR AND DIAGNOSIS (SINGLE PAGE)TRANSMISSIONAUTOMATIC TRANSAUTOMATIC TRANSMISSION - DIAGNOSIS - 4L80-E
1992 GMC Magnavan 5.7 K
Automatic Transmission - Diagnosis - 4L80-E
1992 GMC Magnavan 5.7 KSECTION Automatic Transmission - Diagnosis - 4L80-E
- Application
- Vehicle Code Designation
- Description
- Operation
- Component Description
- Electronic Self-Diagnostics
- Diagnostic Charts
- Notes
- Chart A-1 - No Trans/Service Engine Soon Light
- Chart A-2 - No ALDL Data, No Code 12 Or Trans/Service Engine Soon Light On
- Code 14 - Coolant Temperature Sensor High Temperature Indicated (Signal Voltage Low)
- Code 15 - Coolant Temperature Sensor Low Temperature Indicated (Signal Voltage High)
- Code 21 - Throttle Position Sensor Signal Voltage High
- Code 22 - Throttle Position Sensor Signal Voltage Low
- Code 24 - Output Speed Sensor Low (1991 2WD - Except "C" & "K" Series)
- Code 24 - Output Speed Sensor Low (1991 2WD - "C" & "K" Series)
- Code 24 - Output Speed Sensor Low (1992 2WD)
- Code 24 - Output Speed Sensor Low (4WD)
- Code 28 - Pressure Switch Manifold (PSM)
- Code 39 - TCC Circuit
- Code 53 - System Voltage High
- Code 58 - Trans. Temperature Sensor High Temperature Indicated (Signal Voltage Low)
- Code 59 - Trans. Temperature Sensor Low Temperature Indicated (Signal Voltage High)
- Code 68 - Overdrive Ratio Error
- Code 73 - Force Motor Current
- Code 75 - System Voltage Low
- Code 81 - Shift Solenoid "B" Circuit
- Code 82 - Shift Solenoid "A" Circuit
- Code 83 - TCC Solenoid Circuit
- Code 85 - Undefined Ratio
- Code 86 - Low Ratio
- Code 87 - High Ratio
- Electronic Testing
- Component Test Charts (No Codes)
- Output Speed Sensor Circuit (1991 2WD - Except "C" & "K" Series)
- Output Speed Sensor Circuit (1991 - 2WD "C" & "K" Series)
- Output Speed Sensor Circuit (1992 2WD)
- Output Speed Sensor Circuit (4WD)
- Input Speed Sensor Circuit
- Brake Signal Circuit
- TCC Circuit Check
- Shift Solenoid "A" Circuit
- Shift Solenoid "B" Circuit
- Force Motor Circuit
- Wiring Diagrams
RENDER: 1.0x
NO RELATED
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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.