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.
1988 Cadillac Seville BaseFACTORY OEM SERVICE PROCEDURE
Trouble Code/Symptom Identification
ECM TROUBLE CODE IDENTIFICATION
| Code | Test Condition |
|---|---|
| EO12 | No Distributor (Tach) Signal |
| EO13 | Oxygen Sensor Not Ready |
| EO14 | Shorted Coolant Sensor Circuit |
| EO15 | Open Coolant Sensor Circuit |
| EO16 | Alternator Voltage Out Of Range |
| EO18 | Open Crank Signal Circuit |
| EO19 | Shorted Fuel Pump Circuit |
| EO20 | Open Fuel Pump Circuit |
| EO21 | Shorted TPS Circuit |
| EO22 | Open TPS Circuit |
| EO23 | EST/By-Pass Circuit |
| EO24 | Vehicle Speed Sensor Circuit |
| EO26 | Shorted Throttle Switch Circuit |
| EO27 | Open Throttle Switch Circuit |
| EO28 | Open 3rd-4th Gear Switch Circuit |
| EO30 | ISC Circuit |
| EO31 | Shorted MAP Sensor Circuit |
| EO32 | Open MAP Sensor Circuit |
| EO34 | MAP Sensor Signal High |
| EO37 | Shorted MAT Sensor Circuit |
| EO38 | Open MAT Sensor Circuit |
| EO39 | VCC Engagement Problem |
| EO40 | Open Power Steering Pressure Sw. Circuit |
| EO44 | Lean Exhaust Signal |
| EO45 | Rich Exhaust Signal |
| EO47 | BCM/ECM Data Problem |
| EO48 | EGR System Fault |
| EO52 | ECM Memory Reset Indicator |
| EO53 | Distributor Signal Interrupt |
| EO55 | TPS Misadjusted |
| EO59 | VCC Temperature Sensor Circuit Problem |
| EO60 | Cruise Control/Transmission Not In Drive |
| EO63 | Vehicle Speed/Set Speed Difference Too High |
| EO64 | Cruise Control/Acceleration Too High |
| EO65 | Cruise Control/Coolant Temp. Too High |
| EO66 | Cruise Control/Engine RPM Too High |
| EO67 | Cruise Control Switch Shorted |
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.