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 article 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 MPFI components necessary for start-up and drive. This is a continuous system function for the purpose of alerting the vehicle operator of a needed repair.
"D-check" mode diagnoses entire MPFI system. In "D-check" mode, problem related trouble code(s) are displayed by O2 monitor light. (Scheme 99)or (Scheme 100). 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 article.
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 101)or (Scheme 102). See RELATIONSHIP BETWEEN MODES & CONNECTORS table.
Scheme 99
Scheme 100
Scheme 101
Scheme 102
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
MPFI system requires specific procedures be followed to determine if driveability malfunction is, in fact, MPFI 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
Scheme 103
Scheme 104
Scheme 105
Scheme 106
Scheme 107
Scheme 108
Scheme 109
Scheme 110
Scheme 111
Scheme 112
| Code | Description |
|---|---|
| Code 11 | Crank Angle Sensor |
| Code 12 | Starter Switch |
| Code 13 | Crank Angle Sensor |
| Code 14 | Fuel Injector 1.8L Motor |
| Code 21 | Water Temperature Sensor |
| Code 22 | Knock Sensor 2.7L Motor |
| Code 23 | Airflow Meter |
| Code 24 | By-Pass Air Control Valve |
| Code 25 | Fuel Injector 2.7L Motor |
| Code 31 | Throttle Sensor 1.8L Motor |
| Code 32 | O2 Sensor |
| Code 33 | Speed Sensor |
| Code 35 | Purge Control Solenoid Valve |
| Code 41 | Fuel System |
| Code 42 | Idle Switch |
| Code 51 | Neutral Switch (M/T) |
TROUBLE CODE MENU
Scheme 113
Scheme 114
Scheme 115
Scheme 116
Scheme 117
Scheme 118
Scheme 119
Scheme 120
Scheme 121
Scheme 122
Scheme 123
Scheme 124
Scheme 125
Scheme 126
Scheme 127
Scheme 128
Scheme 129
Scheme 130
Scheme 131
Scheme 132
Scheme 133
Scheme 134
Scheme 135
Scheme 136
Scheme 137
Scheme 138
Scheme 139
Scheme 140
Scheme 141
Scheme 142
Scheme 143
Scheme 144
Scheme 145
Scheme 146
Scheme 147
Scheme 148
CODE 41
Trouble code (41) indicates that the mixture us too lean. When another trouble code is not outputter, all system component are electrically in good order. Check the following
- Injector nozzles (for clogging)
- Fuel pressure
- Performance characteristics of water temperature sensor. NOTE: If the above three are OK, check the following
- Drive some distance after replacing the air flow meter. If still good proceed to next step.
- Replace fuel injectors and drive some distance. If still good proceed to next step.
- Replace control unit.
