15 Amp Efi Fuse Blowing - 2003 Corolla T Sport

[markdeacon]

Hi all,

The 15amp EFI fuse on my 2003 Corolla T sport has blown twice now.

Two days ago on the way home from work, engine cut out while driving at 25mph in traffic, turned out to be the EFI fuse blown.

I was hoping it was going to be a one off however today on the way to work it's blown again in a similar situation, 15mph in traffic and engine cut out.

Done some googling and people seem to think it could be a short to do with the ECU or fuel pump.

Anyone got any experiance troubleshooting EFI fuse problems on a Corolla T sport.

Just want to know what I should be checking first.

Thanks in advance,

Mark

[Mooly]

Just some thoughts on it...

Nothing "electronic" (meaning components within the ECU) will be blowing a 15A fuse and living to work another day. This sounds like either an intermitent short in a wiring loom/junction/fuse box or a problem with a component such as a solenoid/motor/relay/injectors etc that derives its power via the line the fuse supplies.

Biggest clue to finding this would be to study a wiring diagram and see exactly what that 15A fuse feeds. Also if the car is non standard in any way electrically then looking at the work done would be a first port of call.

[MasterMechanic]

Hello, I thought I would post this, since I found the solution for mine. Long story short, it was the Idle Air Speed Control Valve.

 

   My 2003 Toyota Avalon kept on blowing the EFI #2 fuse. I tried looking up the diagram and apparently, there are quite a few things that route to this fuse.

 

   1.) Fuel Injectors, 2.) Mass Airflow Sensor, 3.) Oxygen Sensors (there are three of these), 4.) EVAP System, 5.) Throttle Position Control System, and 6.) Engine Control System.

 

   What I have tried: Unplugging all Oxygen Sensors, unplugging the Mass Airflow Sensor, replacing the ECU, replacing the Fuse Box, unplugging the Fuel Pump, unplugging one Fuel Injector at a time, and unplugging all EVAP solenoids I could identify. But nothing worked. I thought I had unplugged all electrical components on the engine, and maybe blew 30 fuses to test. I even followed the wires to see if there could be a short somewhere. I did not remove was the air box at the time, so I thought, might as well try to follow the wires with a tester (CEN-TECH Cable Tracker from Harbor Freight). That did not work either. I then prayed and asked God to help me find it, so I could move on with other things in my life. I later decided to take off the throttle body and the intake manifold, to see if perhaps a wire shorted back there. As I was going through it, I unplugged a couple of electronic components on the throttle body, and for some reason, I went back into the car to try and start it. Something new lit up when I turned the key to the on position, it was the Check Engine light. So I went ahead and cranked the engine, and the car started up. I looked around to see what I could have nudged or unplugged. And when I plugged back in the Idle Air Speed Control Valve, the fuse started to blow again. But when I unplugged it again, the fuse stopped blowing and the car started up once more.

 

   I really hope that this helps someone. It took me several days to figure this out. I was really considering giving up, called the car a lemon, and was contemplating selling it to a junk yard. But God helped me, so I wanted to post my story out there on a few forums and hope that it can help someone else out too. May God bless you.