Reading Trouble Codes
The ECM stores component failure information for CEC system under a related trouble code which can be recalled for diagnosis and repair. When recalled, these codes will be displayed by flashes of the "CHECK ENGINE" lamp. Trouble codes are displayed starting with the lowest numbered code. Only codes that represent a definite malfunction will be shown.
Trouble codes are read by counting flashes of the "CHECK ENGINE" lamp. For example, "FLASH", "FLASH", pause, "FLASH", longer pause, identifies "21". The first flashes are the first digit of the trouble code; the second series of flashes are the second digit of the trouble code.
ECM TROUBLE CODE IDENTIFICATION
| Code | Circuit Affected | ||
|---|---|---|---|
| 12 | (1) No Reference Pulse | ||
| 13 | Oxygen sensor circuit | ||
| 14 | Shorted coolant sensor circuit | ||
| 15 | Open coolant sensor circuit | ||
| 21 | Open or short in TPS circuit | ||
| 23 | Open or short in M/C solenoid circuit | ||
| 34 | Open or short in vacuum sensor circuit | ||
| 41 | No distributor reference at specified manifold vacuum level | ||
| 42 | Open or short in EST system | ||
| 44 | Lean exhaust indication | ||
| 45 | Rich exhaust indication | ||
| 44 & 45 (Together) | Faulty oxygen sensor circuit | ||
| 51 | Faulty PROM or PROM installation | ||
| 54 | Shorted M/C solenoid circuit or faulty ECM | ||
| 55 | Shorted voltage reference circuit, faulty oxygen sensor or ECM | ||
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