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 MANUALSCHEVROLET1990RV CUTAWAY 7.4 N, 475/M40REPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMENGINE CONTROLS - TESTS W/CODES - TBI
1990 Chevrolet RV Cutaway 7.4 N, 475/M40
Engine Controls - Tests W/Codes - TBI
1990 Chevrolet RV Cutaway 7.4 N, 475/M40SECTION Engine Controls - Tests W/Codes - TBI
- Introduction
- Self-Diagnostic System
- Diagnostic Procedure
- Retrieving Codes (Non-Scan)
- Clearing Trouble Codes
- Diagnostic Materials
- Diagnostic Tests
- Notes
- Chart A-5A: Fuel Pump Relay Circuit "R & V" Series
- Code 13: Open Oxygen Sensor Circuit
- Code 14: Coolant Sensor Signal Voltage Low
- Code 15: Coolant Sensor Signal Voltage High
- Code 21: TPS Signal Voltage High
- Code 22: TPS Signal Voltage Low
- Code 23: Mat Signal Temp Low (2.5L)
- Code 24: Vehicle Speed Sensor (Except 3.1L)
- Code 24: Vehicle Speed Sensor (3.1L)
- Code 25: Mat Sensor Temp. High (2.5L)
- Code 32: EGR System Error 2.5L/5.0L/4.3L Except S & T) & 5.7L (Less Than 8500 GVWR)
- Code 32: EGR System Error 2.8L, 3.1L, 4.3L (S & T), 5.7L (Greater Than 8500 GVWR) & 7.4L
- Code 33: Map Sensor Signal Voltage High
- Code 34: Map Sensor Signal Voltage Low
- Code 35: Idle Speed Error (2.5L)
- Code 42: Electronic Spark Timing (Est) With HEI Ignition
- Code 43: ELEC Spark Control Signal Voltage Low (Except 2.5L)
- Code 44: Lean Exhaust Indication
- Code 45: Rich Exhaust Indication
- Code 51: Faulty Prom/Mem-Cal
- Code 52: Faulty CALPAK (Except 2.5L)
- Code 53: System OVERVOLTAGE (2.5L)
- Code 54: Fuel Pump Circuit (Except 3.1L)
- Code 54: Fuel Pump Circuit (3.1L)
- Code 55: ECM Error (Except 2.5L)
- Summary
RENDER: 1.0x
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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.