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.
1989 Pontiac Grand Prix Base, 2.8 W, StandardFACTORY OEM SERVICE PROCEDURE
3.1L VIN [T] PFI Tests W/Codes
- Diagnosis & Testing
- Diagnostic Circuit Check
- Chart A1, No SES Light
- Chart A2 - No ALDL/Won't Flash Code 12 "Service Engine Soon" ("SES") Light On Steady
- Chart A3, Engine Cranks But Won't Run (1 Of 3)
- Chart A3, Cranks But Won't Run (2 Of 3)
- Chart A3, Cranks But Won't Run (3 Of 3)
- CHART A7, FUEL SYSTEM DIAGNOSIS (1 Of 2)
- CHART A7, FUEL SYSTEM DIAGNOSIS (2 of 2)
- Chart B1: Restricted Exhaust System Check
- Code 13, Open Oxygen Sensor Circuit
- Code 14, Coolant Temp. Sensor Signal Voltage Low
- Code 15, Coolant Temp Sensor (Cts) Signal Voltage High
- Code 21, TPS Signal Voltage High
- Code 22, TPS Signal Voltage Low
- Code 23, Mat Sensor Signal Voltage High
- Code 24, Vehicle Speed Sensor
- Code 25, Mat Signal Voltage Low
- Code 26, Quad-Driver Error (1 Of 3)
- Code 26, Quad-Driver Error (2 Of 3)
- Code 26, Quad-Driver Error (3 Of 3)
- Code 32, EGR System Failure
- Code 33, Manifold Absolute Pressure (Map) Sensor Signal Voltage High
- Code 35, Idle Speed (IAC) Error
- Code 41, Cylinder Select Error
- Code 42, Electronic Spark Timing (Est - W/Dis)
- Code 43, Est
- Code 44, Lean Exhaust Indication
- Code 45, Rich Exhaust Indication
- Code 51, Prom/Mem - CALC Error
- Code 52, CALPAK Error
- Code 53, System OVERVOLTAGE
- Code 55, ECM Error
- Code 62, Gear Switch Error
- Chart C1A, Park/Neutral Switch
- Chart C1D, Map Output Check
- Chart C1E, Power Steering Pressure Switch (PSPS) Check
- Chart C2A, Injector Balance Test
- Chart C2B, Idle Air Control
- Chart C4D1, DISTRIBUTORLESS Ignition System (Dis) Misfire At Idle
- Chart C4D2, DISTRIBUTORLESS Ignition System (Dis) Misfire Under Load
- Chart C5, Electronic Spark Control (ESC)
- Chart C6A, Elect. Air Divert (M/T)
- Chart C7, EGR Check
- Chart C8B, Torque Converter Clutch (TCC) 440-T4 Trans (1 Of 3)
- Chart C8B, TCC 440-T4 Trans (2 Of 3)
- Chart C8B, TCC 440-T4 Trans (3 Of 3)
- Chart C10, A/C Clutch Control
- Chart C12, Cooling Fan Circuit (1 Of 2)
- Cooling Fan Circuit (2 Of 2)
- Component Location
- ECM Terminal Id & Voltage Charts
- Wiring Diagrams
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
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.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
Comes to youSame-day available12-month warranty
Get a Free QuoteNo obligation. See pricing before you book.