Toyota Corolla 2009 will not start due to fuel pump relay damage(Solvde!)

A Toyota Corolla 2009 1.6GL will not start.When starting the starter,it sounded OK.

Toyota Corolla

Diagnosis: The Starter can be started rightly show that storage battery voltage is run in right way. The engine can not be started possible reasons lie below:

  • Vehicle ECM electric circuit failure.
  • Ignition system trouble.
  • fuel injection system trouble.
  • air cylinder pressure trouble.

Trouble Test:

  • Switch the ignition key in IG position,the dashboard light display rightly,and the engine cooling fan does not rotate.The preliminary decision vehicle ECM electronic circuit works normally properly.
  • When start engine,the start works normally.And The engine speedometer has a slight swing, indicating that the engine crankshaft position sensor and its line is normal.
  • Use KT600 diagnostic tool to connect vehicle diagnostic socket DLC3,it can build communication,but trouble code no exist.
  • Engine flash test:it show that each ignition plug work fine,indicating that the ecu can receive the start signal and crankshaft position sensor signal, and the ignition system control circuit is normal.
  • Check the fuel injection control line. Use the diode test lamp, one end of the injector plug 2 terminal, the other end connected to the battery anode, start, the cylinder can make the diode test light flashing, indicating that the cylinder fuel injection control circuit normal.
  • Check the fuel pump control circuit (see circuit diagram 1)

Corolla fuel pump control circuit 1

  • Use KT600 to perform fuel pump active test: Set the ignition switch to IG, select KT600 Diagnostics The following menu items, Power-train / Engine and ECT / Active Test / Control the FuelPump / Speed. When the active test is performed on the diagnostic instrument, the sound of the normal operation of the fuel pump is not heard. Indicating that the fuel pump control line or ECM is faulty. ECM failure rate is relatively low, so I decided to first check the fuel pump control circuit.
  • Use the wire connector and multimeter to measure the main body ECU (shown in Figure 2) on the 2B-10 terminal and the voltage between the ground, the ignition switch placed in the IG block, this time the measured voltage value of 11.68V, Indicating that the fuel pump relay (C / OPN) coil and its front line is normal, start the engine, this time the measured voltage value of 0V, indicating that the vehicle ECM control fuel pump function is normal.

Main body ECU schematic-2

  • Use the wire connector and the multimeter to measure the voltage between the 2B-11 terminal (see Figure 3) and the ground on the main body ECU. Place the ignition switch in the IG block. The measured voltage is 11.68V, indicating that The fuel line in front of the fuel pump relay (C / OPN) contacts is normal.

Main body ECU 2B connector-3


  • Use the wire connector and the multimeter to measure the voltage between the 2A-8 terminal (see Figure 4) and the ground on the main body ECU. When the engine is started and the engine is started, the measured voltage is 0V, indicating fuel Pump relay (C / OPN) switch is not normal.

Main body ECU 2A connector-4

Troubleshooting: According to the test,we determine the fuel pump relay damage. As the fuel pump relay is integrated in the body ECU, to remove the fault, only the overall replacement of the body ECU.Trying to open the body ECU, found on the circuit board and 2A-8 terminal connected to the line ablation.After line welding normally, test, the vehicle starts normal. Upon inquiry, the vehicle had a fault before the IGN fuse was blown, and the maintenance found that the fuel pump jam caused the IGN fuse to blow. Check found that the last maintenance of a change in the protection of the current larger IGN fuse, and found that the engine low speed operation, the oil pressure is low, high-speed operation, the oil pressure normal, then remove the petrol pump assembly, found gasoline pump assembly The fuel port is dirty, the fuel pump power test, fuel pump a little card, the owner agreed to clean the fuel tank, replace the fuel pump assembly and the appropriate IGN fuse, the test all the normal.

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