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.
1990 Isuzu Impulse StandardFACTORY OEM SERVICE PROCEDURE
Engine Controls - Tests W/Codes - 1.6L
- Introduction
- Self-Diagnostic System
- Trouble Code Charts
- Diagnostic Circuit Check
- Notes
- ECM Terminal Identification
- Chart A-1: No Check Engine Light
- Chart A-2: No ALDL Data Or No Flash Code 12 (Check Engine Light On Steady)
- Code 13: O2 Sensor (Heated Sensor Only) Open/Shorted Circuit
- Code 14A: Cts Circuit (Hi Temp Indicated)
- Code 14B: Cts Circuit (Low Temp Indicated)
- Code 21A: TPS Circuit (Signal Volt High)
- Code 21B: TPS Circuit (Signal Volt Low)
- Code 23A: Mat Sensor CKT (Lo Temp Indicated)
- Code 23B: Mat Sensor CKT (Hi Temp Indicated)
- Code 24: VSS Circuit
- Code 33A: Map Sensor (Signal Volt Hi)
- Code 33B: Map Sensor (Signal Volt Lo)
- Code 42: Est (Electronic Spark Timing)
- Code 44: O2 Sensor Lean Fuel Mixture (Heated Sensor Only)
- Code 45: O2 Sensor Rich Fuel Mixture (Heated Sensor Only)
- Code 51: ECM Failure
- Summary
Factory Service Tools
Use the Manual With the Right Hardware
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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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