Engine (Diagnostics) - 2.0L: Precautions
Airbag system wiring harness is routed near the ECM, main relay and fuel pump relay.
- All airbag system wiring harness and connectors are colored Yellow. Do not use electrical test equipment on these circuit.
- Be careful not to damage the airbag system wiring harness when servicing ECM, TCM, main relay and fuel pump relay.
Never connect the battery in reverse polarity.
- The ECM will be destroyed instantly.
- The fuel injector and other part will be damaged in just a few minutes more.
Do not disconnect battery cables while engine is running.
A large counter electromotive force will be generated in alternator, and this voltage may damage electronic parts such as ECM, etc.
Before disconnecting connectors of each sensor and ECM, be sure to turn ignition switch to OFF.
Poor contact has been identified as a primary cause of this problem. To measure voltage and/or resistance of individual sensors or all electrical control modules at the harness side connector, use a tapered pin with a diameter of less than 0.64 mm (0.025 in). Do not insert the pin more than 5 mm (0.20 in) into the part.
Before removing ECM from located position, disconnect 2 cables on battery. Otherwise, ECM may be damaged.
The connectors to each sensor in the engine compartment and the harness connectors on the engine side and body side are all designed to be waterproof. However, it is still necessary to take care not to allow water to get into the connectors when washing the vehicle, or when servicing the vehicle on a rainy day.
Use ECM mounting stud bolt at body head grounding points when measuring voltage and resistance inside passenger compartment.
- Stud bolt
Use engine grounding terminal or engine proper as grounding point to body, when measuring voltage and resistance in the engine compartment.
Use the TCM mounting stud bolts at the grounding point, when measuring voltage and resistance inside the passenger compartment.
- Stud bolt
Every MFI-related part is a precision part. Do not drop them.
Observe the following cautions when installing a radio in MFI equipped models.
- The antenna must be kept as far apart as possible from the control unit.
(The ECM is located under the steering column, inside of the instrument panel lower trim panel.)
- The antenna feeder must be placed as far as possible from ECM and MFI harness.
- Carefully adjust the antenna for correct matching.
- When mounting a large power type radio, pay special attention to the three items above mentioned.
- Incorrect installation of the radio may affect the operation of ECM.
Before disconnecting the fuel hose, disconnect the fuel pump connector and crank the engine for more than 5 seconds to release pressure in the fuel system. If the engine starts during this operation, run it until it stops.
Problems in the electronic-controlled automatic transmission may be caused by failure of the engine, the electronic control system, the transmission proper, or by a combination of these. These three causes must be distinguished clearly when performing diagnostics.
Diagnostics should be conducted by rotating with simple, easy operations and proceeding to complicated, difficult operations. The most important thing in diagnostics is to understand the customer's complaint, and distinguish between the three causes.
On model with ABS, when performing driving test in jacked-up or lifted-up position, sometimes the warning light may be lit, but this is not a malfunction of the system. The reason for this is the speed difference between front and rear wheels. After diagnosis of engine control system, perform the ABS memory clearance procedure of self-diagnosis system.