Attention: see the section "Rules for performing work in the engine compartment" chapters "Maintenance and general inspection and adjustment procedures".
Precautionary measures
1. Before troubleshooting the fuel injection system, check that the engine settings are correct (see chapter "Maintenance and general inspection and adjustment procedures").
2. Before disconnecting the connectors of the electronic control unit, it is necessary to turn off the electrical supply using either the ignition key. or by removing the wires from the battery terminals.
Attention: be sure to read the diagnostic codes before disconnecting the wires from the battery terminals.
3. When installing the battery, do not scare the polarity of connecting wires to its terminals.
4. Do not hit the elements of the fuel injection system and especially the electronic control unit.
5. Be careful when troubleshooting, with a large number of transistor circuits, even slight careless touching of the terminals can cause serious damage.
6. Do not open the housing cover of the electronic control unit.
7. When operating in rainy weather, keep the electronic controls away from water. The same should be done when washing the engine.
8. Be careful when disconnecting and connecting electrical wiring connectors.
9. To avoid misfiring after repairs, take the following precautions.
- A) Check up reliability of connection of wires with plugs of the storage battery.
- b) Handle high voltage spark plug wires with care.
- V) At the end of the repair work, make sure that all wires of the ignition system are correctly and securely connected.
Checking connectors
1. Connecting and disconnecting connectors.
- A) When disconnecting, loosen the lock by pushing the spring and pull out the connector by holding it by the housing.
Caution: Do not disconnect the connector using the wiring harness, as this may damage the wire or cause poor contact in the connector.
- b) When connecting, fully insert the connector and make sure it is locked.
2. Checking the quality of the connection in the connector.
Attention: malfunctions in the electronic control system can be caused by incorrect connection of the electrical wiring connectors. However, when checking the system, the symptom may disappear if the connectors are repeatedly disconnected and connected. Possible causes of such malfunctions are:
- The connector is disconnected or the connector is connected incorrectly.
- Loss of connector pins.
- Poor contact in the connector due to excessive tension on the wiring in the connector
- Poor contact due to corroded connector pins or foreign particles getting inside.
- A) If the pin stopper 8 of the connector is damaged, the pins may fall out from the reverse side of the connector, even with the connector connected. Therefore, it is necessary to carefully pull each wire from the back of the connector and make sure that there are no pins falling out.
- b) To check the reliability of contact between the terminals, use a special tool. The withdrawal force must be at least 1 N.
3. Check on connector pins.
Attention:
- Never use force when connecting the probe, as this may damage the lead or cause poor contact in the connector. If you cannot insert the probe into a socket that is too small (control unit, etc.) you need to use an ultra-fine probe.
- Be very careful when checking to avoid short-circuiting the leads. Shorting the leads can damage the circuits inside the ECM.
4. Peculiarities of testing on the terminals of hermetic connectors.
Attention: when testing circuits with sealed (waterproof) connectors, it is recommended to use the test lead harness.
- A) If the test harness is missing. then carefully remove the protective cover.
- b) When testing resistance, current, or voltage, always insert the tester probe from the wire side.
Attention: never insert the probe directly into the connector from the wire side through the protective cover, as this will lead to leakage of the connector and corrosion.
- G) After checking, firmly install the protective cover on the connector.
Wiring check
1. When checking the wiring harness for an open, when the ends of the wire being tested are far apart, use a wire with a connector "crocodile" to connect one end of the wire to "weight", and then check for a closed circuit between the second end of the wire and "weight". If the circuit is open, repair the wiring.
Note: however, when checking the power line wire for an open circuit, check for a closed circuit directly between both ends of the wire, without using a connector "crocodile" to connect one end of the wire to "weight".
2. When checking the circuit for a short circuit (on "mass") disconnect one end of the wire and check for an open circuit between "weight" and the other end of the wire. If the circuit is closed (short circuit), then repair the wiring.
Note: When checking circuit condition, use an analog ohmmeter or multimeter.
3. If the wiring is OK, but the voltage (nutrition), supplied to the sensor is different from normal, substitute a known-good engine control module and recheck.
Warning: Use a digital voltmeter when checking voltage (or multimeter). However, when checking the voltage in the power transistor circuit, an analog voltmeter should be used.
Checking the circuit with a blown fuse
1. Remove the fuse and measure the resistance between "weight" and load contact of the fuse.
- A) Set the switches of all circuits related to this fuse to the closed position.
- b) If at the same time the resistance is almost zero, then a short circuit occurs in the circuit between the switches and the load.
- V) If the resistance is greater than zero, then 8 there is currently no short circuit. However, the momentary short circuit caused the fuse to blow.
2. The main causes of short circuit are:
- A) Pinching the wire with a body part.
- b) Insulation damage due to wear or overheating.
- V) Water ingress into connector or circuit.
- G) Human factor (erroneous shorting of the circuit, etc.).
Search for intermittent malfunctions
1. Intermittent faults (when the symptom may not reappear) often occur under certain conditions and if these conditions can be established, then it is easy to determine the cause of the malfunction. To determine the conditions under which a malfunction occurs. First of all, information about driving conditions, weather conditions, frequency of repetitions and symptoms of a malfunction is needed.
2. Perform a simulation test to reproduce the conditions for the failure to occur.
- A) When the main cause of the malfunction is probably vibration then:
- Gently shake the connector up and down, right and left.
- Gently shake the wire up, down, right, and left.
- Gently shake each sensor, relay, etc. by hand.
- Gently shake the wire harnesses routed to the suspension and other moving parts.
Note: if any wire shows signs of mechanical damage (strong bend, break, insulation cut, etc.), then a new wire must be connected instead.
- b) When the root cause of the problem is probably overheating, use a hair dryer to heat up the component that is suspected to be causing the problem.
Caution: Do not heat system components above 80°C.
- V) When the main cause of the malfunction is likely to be increased resistance in electrical circuits, then install all electrical appliance switches (including headlight switches and rear window defroster switch) into position "ON" (ON).
- G) If the symptom does not reappear even after performing the above checks, then the troubleshooting should be temporarily stopped.