INTRODUCTION
If no faults were found while performing BASIC TESTING, proceed with ENTERING SELF-DIAGNOSTICS in this article. If no fault codes or only pass codes are found, proceed to TESTS W/O CODES for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.).
"HARD FAILURES"
When system failures occur, "check engine" light illuminates. This function, termed the "U-check" mode, monitors only the SPFI components necessary for start-up and drive. This is a continuous system function for the purpose of alerting the vehicle operator to a needed repair.
"D-check" mode diagnosis entire SPFI system. In "D-check" mode, problem related trouble code(s) are displayed on O2 monitor. (Scheme 24)or (Scheme 25). The code(s) remain accessible until malfunction is repaired. Malfunction is determined using diagnostic (code) charts. If more than one code is present, the lowest number trouble code is to be diagnosed first.
"INTERMITTENT FAILURES"
Intermittent failures may cause "check engine" light to flicker or illuminate and go out after intermittent fault quits. The corresponding trouble code may be retained in control unit "read memory". This mode is most effective in detecting poor contact or loose connections of connectors, harnesses, etc. If intermittent fault is not retained in "read memory", see INTERMITTENTS in TESTS W/O CODES section.
ENTERING SELF-DIAGNOSTICS
"U-Check", "Read Memory" and "D-Check" are entered by connecting and/or disconnecting the read memory and test mode connectors as required. (Scheme 26)or (Scheme 27). See RELATIONSHIP BETWEEN MODES AND CONNECTORS table.
Scheme 24
Scheme 25
Scheme 26
Scheme 27
MODES & CONNECTORS
| Mode | Engine | Read Memory | Test Mode |
|---|---|---|---|
| U-Check | Ign. On | Disconnected | Disconnected |
| Read Memory | Ign. On | Connected | Disconnected |
| D-Check | Ign. On | Disconnected | Connected |
| Clear | Engine On | Connected | Connected |
RELATIONSHIP BETWEEN MODES & CONNECTORS
BASIC OPERATION OF SELF-DIAGNOSIS SYSTEM
SPFI system requires specific procedures be followed to determine if driveability malfunction is, in fact, EFC system component related. Use the NO TROUBLE and TROUBLE tables to determine source of malfunction.
SUMMARY
If no hard fault codes (or only pass codes) are present, proceed to TESTS W/O CODES for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.), or intermittent diagnosis procedures.
| Abbreviation | Color |
|---|---|
| BR | Black/Red |
| BW | Black/White |
| BY | Black/Yellow |
| G | Green |
| GB | Green/Black |
| GL | Green/Blue |
| GR | Green/Red |
| GW | Green/White |
| GY | Green/Yellow |
| Lg | Light Green |
| LgB | Light Green/Black |
| LR | Blue/Red |
| LW | Blue/White |
| LY | Blue/Yellow |
| RY | Red/Yellow |
| W | White |
| WB | White/Black |
| WR | White/Red |
| WY | White/Yellow |
| Y | Yellow |
| YL | Yellow/Blue |
| YR | Yellow/Red |
| YW | Yellow/White |
WIRE COLOR ABBREVIATIONS USED IN CODE CHARTS
