Engine Controls - Tests W/codes - 2.6l Efi Isuzu Amigo I

INTRODUCTION

If no faults were found while performing F - EFI BASIC TESTING, proceed with self-diagnostics. If no fault codes or only pass codes are present after entering self-diagnostics, proceed to H - EFI TESTS W/O CODES article in the ENGINE PERFORMANCE Section for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.).

HARD FAILURES

Hard failures cause CHECK ENGINE light to illuminate and remain on until problem is repaired. If light comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined using diagnostic (code) charts. If a sensor fails, Electronic Control Module (ECM) will use a substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, the vehicle runs but driveability will not be optimum.

INTERMITTENT FAILURES

Intermittent failures may cause CHECK ENGINE light to flicker or illuminate and go out after the intermittent fault goes away. However, the corresponding trouble code will be retained in Electronic Control Module (ECM) memory. If related fault does not reoccur within a certain time frame, related trouble code will be erased from ECM memory. Intermittent failures may be caused by a sensor, connector or wiring related problems. See INTERMITTENTS in H - EFI TESTS W/O CODES article in the ENGINE PERFORMANCE Section.

RETRIEVING CODES

Note. Codes can also be retrieved using a Scan tester. Diagnostic connector may also be referred to as ALDL test lead.

1. Code retrieval starts with the DIAGNOSTIC CIRCUIT CHECK. The CHECK ENGINE light will come on when ignition is on and engine is not running. When engine is started, CHECK ENGINE light should go off. If light remains on while engine is running, a trouble code is present.
2. If light did not come on with key on and engine off, inspect CHECK ENGINE light circuit before continuing. If CHECK ENGINE light failed to operate, See DIAGNOSTIC CIRCUIT CHECK. Circuit checks are located within test charts.
3. To retrieve codes, install jumper wire between ALDL diagnostic leads. (Scheme 85) Turn ignition on. Count number of flashes from CHECK ENGINE light. A Code 12 is identified by a flash, pause and flash, flash. A long pause will occur. Code 12 will repeat 3 times. (Scheme 86) Each additional code will flash 3 times starting with lowest code to the highest number code. Once all codes are displayed, codes will repeat.
4. If system is operating properly (with no codes), a Code 12 should exist with ignition on and engine off. This indicates the diagnostic system is capable of storing codes. After codes are retrieved, remove jumper wire from diagnostic leads to exit diagnostic mode.

Scheme 85

Scheme 86

CLEARING CODES

1. After repairs are performed, clear ECM memory of all stored codes. To clear memory, turn ignition off and remove appropriate fuse from fuse block. See CLEARING CODES table.
2. Trouble codes can also be cleared by disconnecting negative battery cable. However, other memory functions (clock, radio, etc.) will then require resetting.

CLEARING CODES

ECM LOCATIONS

TROUBLE CODE IDENTIFICATION

TROUBLE CODE IDENTIFICATION

ECM TERMINAL IDENTIFICATION

Scheme 87

DIAGNOSTIC CIRCUIT CHECK

Scheme 88

TEST NO. 1 - ECM POWER SUPPLY

Checking ECM Unit Power Supply Circuit

Confirmation

1. Disconnect ECM unit harnesses at connectors.
2. Turn key switch to ON position.
3. Check that power voltage is present at connector terminals 33, 12 or 21.
4. Check that continuity exists between the connector and terminals 11, 20 and ground.

Inspection And Correction

1. When power voltage is not present at terminals 33 and 12 or 21. Check the main relay, starter switch, fuses, fusible link wires and related circuits and correct or replace the parts as necessary.
2. If the circuit tester does not indicate continuity across the terminals 11, 20 and ground, correct or replace grounding cable.
3. Connect the ECM unit harnesses at connector properly.

Scheme 89

TEST NO. 2 - CHECK ENGINE LIGHT INOPERATIVE

Note. Before replacing ECM, use an ohmmeter and check resistance of each ECM controlled relay and solenoid coil. See ECM wiring diagram for coil terminal identification for solenoid(s) and relay(s) to be checked. Replace any relay or solenoid if the coil resistance measures less than 20 ohms.

Scheme 90

Scheme 91

Scheme 92

Scheme 93

CODE 12 - SYSTEM NORMAL

Code No. 12 is always displayed when the key is ON and the engine is not running and it only means that the engine is not running. This code No. 12 is not stored in memory.

Note. If the signal code No. 12 only is displayed when the function key is operated after clearing the memory, it indicates that the ECM electrical circuits and self diagnosis system are functioning normally.

Scheme 94

Scheme 95

Scheme 96

Scheme 97

Scheme 98

CODE 21 - THROTTLE VALVE SWITCH (IDLE & FULL THROTTLE)

THROTTLE VALVE SWITCH RESISTANCE

Scheme 99

Scheme 100

Scheme 101

CODE 22 - STARTER SIGNAL

Note. Starter relay is located in relay box, in engine compartment.

Scheme 102

Scheme 103

Diagnostic Aid

If code 23 is displayed, there should be no continuity between circuit 5 and ground. If code 35 is displayed, there should be continuity between STAY of power transistor and intake manifold. If code 54 is displayed, there should be continuity between circuit 10 and ground.

Scheme 104

Scheme 105

If code 25 is displayed, voltage between BLACK/WHITE wire and ground should be 12 volts and resistance between LIGHT GRAY/YELLOW wire and circuit No. 4 should be zero. If code 53 is displayed, resistance between circuits No. 9 and 10 and ground should be zero.

Scheme 106

Scheme 107

Scheme 108

Scheme 109

Scheme 110

Specified Reappearance Pattern

1. Run engine at idle condition, at normal operating temperature.
2. Keep at idle for more than 10 seconds, with vehicle stopped
3. Drive vehicle at just over 10 MPH. Accelerate quickly to more than 30 MPH (must reach 30 MPH within 10 seconds of starting acceleration).
4. Within 30 seconds, decelerate safely to a complete stop. (Scheme 112)
5. Repeat above procedure 2) through 4) several times.

Scheme 111

Scheme 112

Scheme 113

Scheme 114

1. Check circuit 21 with key ON, engine stopped. Measure the voltage between terminal 75 and battery (-) at Dropping Resistor connector. (Scheme 117) Voltage should be more than 8 volts.
2. Measure the voltage difference between battery (+) and each injector at Dropping Resistor connector. Voltage should be almost zero volts.
3. Measure the voltage difference between battery (-) and each injector at Dropping Resistor connector. Voltage should be more than 8 volts.
4. With key OFF, disconnect all ECM connectors. Then with key ON, measure the voltage between battery (+) and injector terminals.
5. Measure the voltage of injector terminals No. 1 and 2 at ECM connector (10 pin).

Scheme 115

Scheme 116

Scheme 117

Resistance between ECM terminal 26 and GRY/YEL and between ECM terminal 38 and BLK should be zero ohms. Resistance between ECM terminal 38 and ground should be zero ohms. Resistance between ECM terminals 11 and 20 and ground should be zero.

Scheme 118

Scheme 119

Scheme 120

Scheme 121

CODE 35 - POWER TRANSISTOR CIRCUIT

See Code No. 23.

CODE 41 - CRANK ANGLE SENSOR SIGNAL

Note. Wire colors may vary. See WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section..

1. Disconnect crank angle sensor harnesses at crank angle sensor connector.
2. Disconnect all connectors at ECM.
3. Turn ignition ON. Measure resistance between terminals 34 and WHITE, 35 and GREEN and BLACK and ground. Resistance should be zero.
4. Measure voltage between GREEN/BLACK and ground. Voltage should be 10-14 volts.
5. When circuit is found to be in normal condition, replace distributor assembly.

Scheme 122

Scheme 123

Scheme 124

CODE 43, 65 - THROTTLE VALVE SWITCH

THROTTLE VALVE SWITCH RESISTANCE

Scheme 125

Scheme 126

Scheme 127

Scheme 128

Scheme 129

Scheme 130

Scheme 131

Scheme 132

Circuit Connections

1. Disconnect the control unit harnesses at connector and check for proper connections at terminals.
2. Regardless of terminal conditions, road test the vehicle with all the harnesses reconnected at the connector.
3. Obtain display of trouble code and see if the trouble has been corrected. If the trouble persists, replace the ECM.

CODE 53 - PRESSURE REGULATOR VSV

See Code No. 25.

CODE 54 - POWER TRANSISTOR CIRCUIT

See Code No. 23.

Inspection Of Airflow Sensor

Uncover the rubber boot on the air flow sensor side of the harness connector. Check resistance an voltage of terminals. See AIRFLOW SENSOR SIGNAL table.

AIRFLOW SENSOR SIGNAL

CIRCUIT WIRING RESISTANCE

Scheme 133

Scheme 134

Scheme 135

CODE 63 - VEHICLE SPEED SENSOR SIGNAL

Code 63 may be displayed even if the system is normal if the vehicle is used under the following conditions

1. A/T; In "D" range, while depressing the brake pedal, the accelerator pedal is depressed over 1/2 throttle for more than 3 seconds
2. M/T; Under the severe climbing conditions, keep the vehicle stopped while the accelerator pedal depressed over 1/2 throttle for more than 3 seconds

Sensor & Equipment

1. Connect a circuit tester between the control unit harness connector terminal 41 and ground.
2. Disconnect speedometer cable at transmission end and turn the inner cable slowly.
3. If the tester indicates continuity and open circuit condition alternately as the cable is turned, the car speed sensor and circuit are operating normally

Wiring Circuits

Check resistance between YELLOW and Circuit 41 (Scheme 137), reading should be zero ohms. Check resistance between BLACK and ground, there should be infinite resistance.

Car Speed Sensor

1. Remove the speedometer assembly.
2. Connect the leads of a circuit tester across terminals 1 and 2 at rear face of the meter assembly. (Scheme 138)
3. Turn the inner shaft slowly and check that the tester indicates a continuity and open circuit condition alternately. If speed sensor is inoperative, replace speedometer assembly.

Scheme 136

Scheme 137

Scheme 138

Scheme 139

Scheme 140

Scheme 141

Scheme 142

CODE 65 - THROTTLE VALVE SWITCH

See Code No. 43.

SUMMARY

If no hard fault codes (or only pass codes) are present, driveability symptoms exist or intermittent codes exist, proceed to H - EFI TESTS W/O CODES article in the ENGINE PERFORMANCE Section for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.) or intermittent diagnosis procedures.

See also:
• 12
• 13
• 21
• 22
• 35
• 41
• 43
• 53
• 54
• 63