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 Ford Thunderbird BaseFACTORY OEM SERVICE PROCEDURE
Symptom/Test Menu
DIAGNOSIS BY SYMPTOM (SYMPTOM-TO-CIRCUIT TEST MENU)
| Symptom | Go To: Circuit Test No. (Step No.) |
|---|---|
| Runs Rough, Misses, Stalls, Lacks Power, Rough Idle, Surges, Stalls In Self-Test | D19 (2) |
| Stalls At Idle Or During Self-Test | D19 (1) |
| Stalls When Parking (AXOD SEFI only) | B15 (3) |
| A/C Stays On During WOT (AXOD SEFI & SC SEFI only) | D23 (44) |
| A/C Stays On During WOT (RWD SEFI only) | D7 (11) |
| A/C Not Functioning (AXOD SEFI & SC SEFI only) | D23 (42) |
| A/C Not Functioning (RWD SEFI only) | D7 (11) |
| Low Idle With A/C On | B13 (10) |
| High Idle In "Drive" A/T Trans Only (RWD SEFI only) | B13 (15) |
| Shift Indicator Light Always/Never On (SC SEFI only) | D6 (1) |
| "CHECK ENGINE" Light Always On | D11 (1) |
| "CHECK ENGINE" Light Never On | D11 (2) |
| "CHECK ENGINE"/"CHECK DCL" Message On (AXOD SEFI only) | D11 (8) |
| "CHECK ENGINE" Message On (AXOD SEFI only) | D11 (7) |
| "CHECK ENGINE" Light On Intermittently | D11 (5) |
| "CHECK ENGINE" Light Flashes With Erratic Idle | D11 (6) |
| Lack Of Power At WOT | N/A |
| Tachometer Inoperative | N/A |
| Stumble After Hot Restart | C1 (19) |
| Fuel Pump Runs With Engine Off (SC SEFI only) | C2 (14) |
| Gasoline Fumes In Engine Compartment | D4 (1) |
| Detonation/Spark Knock (SC SEFI only) | D8 (1) |
| Poor Performance, Low Or High Supercharger Pressure (SC SEFI only) | D9 (6) |
| Engine Cooling Fan Inoperative (Single Speed Fan) | N/A |
| Engine Cooling Fan Inoperative (Dual Speed Fan) (AXOD SEFI & SC SEFI only) | D23 (17) |
| Cooling Fan Always On (AXOD SEFI only) | D23 (30) |
| Cooling Fan Always On (SC SEFI only) | D23 (33) |
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.