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.
1991 Cadillac Seville BaseFACTORY OEM SERVICE PROCEDURE
General Motors A & C Chart Reference
GENERAL MOTORS A & C CHART REFERENCE
| System or Component | Diagnostic Information Location | ||
|---|---|---|---|
| A1 & A2, "SERVICE ENGINE SOON" Light | See DIAGNOSTIC CIRCUIT CHECK In BASIC TESTING Article | ||
| A3, No Start | See NO START - ENGINE CRANKS OKAY In BASIC TESTING Article | ||
| A5, Fuel Pump Relay | See MOTORS, RELAYS & SOLENOIDS In This Article | ||
| A7, Fuel System Diagnosis | See BASIC FUEL SYSTEM CHECKS In BASIC TESTING Article | ||
| C1, MAP Sensor | See ENGINE SENSORS & SWITCHES In This Article | ||
| C1, Power Steering Pressure Switch | See ENGINE SENSORS & SWITCHES In This Article | ||
| C1, Park/Neutral Switch | See ENGINE SENSORS & SWITCHES In This Article | ||
| C2, Injector Balance Test | See FUEL CONTROL In This Article | ||
| C2, IAC Motor | See IDLE CONTROL SYSTEM In This Article | ||
| C2, ISC Motor | See IDLE CONTROL SYSTEM In This Article | ||
| C3, Canister Purge System | See EMISSION SYSTEMS & SUB-SYSTEMS In This Article | ||
| C4, EST Ignition Check | See BASIC IGNITION SYSTEM CHECKS In BASIC TESTING Article | ||
| C4, DIS Ignition "Misfire" | See DIS MISFIRE - 3.1L (VIN T) "W" BODY - C4F Chart In This Article. | ||
| C5, ESC Ignition Check | See IGNITION SYSTEM In This Article | ||
| C6, Air Injection System | See EMISSION SYSTEMS & SUB-SYSTEMS In This Article | ||
| C7, EGR System | See EMISSION SYSTEMS & SUB-SYSTEMS In This Article | ||
| C8, Torque Converter Clutch | See MISCELLANEOUS ECM CONTROLS In This Article | ||
| C8, Manual Trans. Shift Lights | See MISCELLANEOUS ECM CONTROLS In This Article | ||
| C10, A/C Clutch Control | (1) See MISCELLANEOUS ECM CONTROLS In This Article | ||
| C12, Electric Cooling Fan Control | (1) See MISCELLANEOUS ECM CONTROLS In This Article | ||
|
|||
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.