Older style Toyota flap-style merchanical airflow meter. So the meter's output voltage drops as airflow increases. The greater the air flow, the higher the resistance created by the potentiometer. This changes the airflow meter's output voltage in proportion to airflow. Connected to the flap is a arm that rubs across a resistor grid (potentiometer). A flap inside the meter rotates when incoming air pushes against it. On the older Toyota EFI systems, air flow is measured mechanically with a flap-style airflow meter. To regulate the air/fuel mixture, the engine computer needs to know how much air is being sucked into the engine. HOW TOYOTA FUEL INJECTION MEASURES AIRFLOW Even so, older high mileage cars and trucks can develop problems common to all fuel injection systems: pumps wear out, regulators fail, injectors become dirty or worn, cold start injectors can leak, and intake systems can become restricted due to accumulated carbon and fuel varnish. The system has evolved over the years and has earned a reputation for being relatively trouble-free. The multiport fuel injection system Toyota has used from the early 1980s to the 1990s on its various engine families is based on the Bosch L-Jetronic system.
The display will indicate any diagnostic codes stored in the ECU's keep alive memory.Auto Repair Library, Auto Parts, Accessories, Tools, Manuals & Books, Car BLOG, Links, Indexĭiagnose Toyota Fuel Injection by Larry Carley copyright 2019 When the "DIAG" message appears on the display, pressing and holding the "Set" key for three seconds will put the TCCS system into diagnostic mode. This display can be used to read diagnostic codes by simply pressing and holding the monitor "Select" and "Input M" keys together, for three seconds, with the ignition switch in the "on" position. Super Monitor Display: On some 1983 through 1987 Cressida and Supra models, a Super Monitor trip computer was offered as optional equipment.
It is important to refer to the proper repair manual for specific information about diagnostic connector location, code format, and proper procedures for the vehicle you are troubleshooting. An analog voltmeter must be used to read the codes from the VF terminal of the EFI Service Connector.ĭepending on the vintage of the system being tested, the codes will be displayed in either one or two digit format. On '83 through '85 Cressida and Supra models, the check engine light does not flash diagnostic codes. Low voltage on T causes the ECU to enter diagnostic mode, producing diagnostic codes on the check engine light. When the T terminal is grounded with the ignition switch in the "on" position, the ECU sees the voltage at terminal T go low. Jumper check connector terminals T (TE1) to E1.Confirm that the throttle is closed (IDL contact on).Turn the ignition switch to the "on" position and make sure that the check engine light is on.Locate the check connector under the hood and identify the T (TE1 on late model TCCS) and E1 terminals.The E1 ground circuit is also located in the check connector. When grounded, this terminal triggers the self diagnostic feature of the ECU. All engines equipped with self diagnostic systems have one terminal of the check connector identified as T or TE1. The procedure to examine the ECU memory for diagnostic codes is typically very simple regardless of which vintage engine being diagnosed. Earlier models use this same multiple terminal or a two-terminal check connector, all located under the hood.
All late model TCCS applications, from 1988, use a multiple terminal diagnostic check connector. There are several different types and locations of diagnostic connectors which are used to trigger and, in some cases, read diagnostic code output from Toyota EFI engines.