EFI Fuse killing battery overnight
01-18-10, 06:25 PM
#16
YEEESSSSS!!!!! 
After over a year of trying to temporarily solve this problem with all kinds of haphazard chargers, brains, switches, and batteries, I've finally made "actual" progress towards a solution.
I've tested the parasitic draw at least 100 times (no joke; probably closer to 500) and I've never gotten a reading over .075ma. It may seem a little high but a good battery should still last a couple of weeks with such a draw; my battery would only last 8 hours to 3 days max. This is what always stumped me
Then I stumbled onto this article http://diagnosticnews.com/tech/paras...attery-drains/ which said that while testing for a parasitic drain/draw a battery disconnect switch may be needed to insure that unplugging the battery does not effect the test.
After following the instructions from the link and without disconnecting the battery, I got a reading of..................1.68 AMPS!!! I've never been so happy to see something wrong with my car lol. And as I expected, when the EFI fuse was removed the drain dropped to an acceptable .053 ma. When the EFI fuse was replaced, the drain stayed at .053ma (that's the tricky part that has been stumping me). The 1.6 amp draw was also erased when the main efi relay was removed. I switch the efi relay with another one, but got the same results so the relay is NOT the problem (I think).
Any electrician/wiring experts out there? Any ideas of what would cause an approximate 1.6 amp draw in this circuit? How to check/fix this? I'm not that good with wiring so any help is appreciated.
THANKS A TON!!!
After over a year of trying to temporarily solve this problem with all kinds of haphazard chargers, brains, switches, and batteries, I've finally made "actual" progress towards a solution.
I've tested the parasitic draw at least 100 times (no joke; probably closer to 500) and I've never gotten a reading over .075ma. It may seem a little high but a good battery should still last a couple of weeks with such a draw; my battery would only last 8 hours to 3 days max. This is what always stumped me
Then I stumbled onto this article http://diagnosticnews.com/tech/paras...attery-drains/ which said that while testing for a parasitic drain/draw a battery disconnect switch may be needed to insure that unplugging the battery does not effect the test.
After following the instructions from the link and without disconnecting the battery, I got a reading of..................1.68 AMPS!!! I've never been so happy to see something wrong with my car lol. And as I expected, when the EFI fuse was removed the drain dropped to an acceptable .053 ma. When the EFI fuse was replaced, the drain stayed at .053ma (that's the tricky part that has been stumping me). The 1.6 amp draw was also erased when the main efi relay was removed. I switch the efi relay with another one, but got the same results so the relay is NOT the problem (I think).
Any electrician/wiring experts out there? Any ideas of what would cause an approximate 1.6 amp draw in this circuit? How to check/fix this? I'm not that good with wiring so any help is appreciated.
THANKS A TON!!!
01-20-10, 02:52 PM
#17
Any suggestions? I disconnected the fuel pump ecu and but the drain remained the same.
What component tied into the EFI fuse (or EFI relay) could be the culprit?
Background:
I've got a 1.68 amp drain that drops to .052 ma when I remove the EFI fuse or EFI relay. But if I put the fuse (or relay) back in it's socket the drain remains at .052 ma. The drain goes back to 1.6 amps when I turn the key into the ACC or ON position (the position when you turn the key all the way w/o trying to crank the engine). Any idea?!
What component tied into the EFI fuse (or EFI relay) could be the culprit?
Background:
I've got a 1.68 amp drain that drops to .052 ma when I remove the EFI fuse or EFI relay. But if I put the fuse (or relay) back in it's socket the drain remains at .052 ma. The drain goes back to 1.6 amps when I turn the key into the ACC or ON position (the position when you turn the key all the way w/o trying to crank the engine). Any idea?!
12-03-10, 08:09 PM
#18
Did you ever figure this out? I have the exact same problem, i sent the ecu out for repair and they said they found a fault but i got it back and no dice. I replaced the relay, fuel pump is not running after off or anything. Relay does get hot and problem goes away when you pull the relay or efi fuse. Then it is back when you turn the key to on then back off.
12-23-10, 05:19 PM
#19
Well ECU repair didn't work and i got another ECU and that didn't work either. I think ill just drive it into a lake....
Between it not being the ecu, or relay all i have between there is injectors and ignition switch, its not the fuel pump control either
Between it not being the ecu, or relay all i have between there is injectors and ignition switch, its not the fuel pump control either
Last edited by twizted; 12-23-10 at 05:26 PM.
12-23-10, 10:20 PM
#20
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^ How long does the 1.68A stay?
*All checking to be done with the 1.68 amp draw.
You might try to do volt drops on ALL the ecu grounds, as well as get an amp probe and check each wire at the ecu to find where the current is going. I have seen power back feed through fuse boxes, modules, all kinds of wonderfull headaches.... There is a reason it has a problem, with some more time you will get it. Good luck!
*All checking to be done with the 1.68 amp draw.
You might try to do volt drops on ALL the ecu grounds, as well as get an amp probe and check each wire at the ecu to find where the current is going. I have seen power back feed through fuse boxes, modules, all kinds of wonderfull headaches.... There is a reason it has a problem, with some more time you will get it. Good luck!
03-14-11, 02:23 PM
#24
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I had a similiar problem in my supra that somehow fixed itself or I unknowingly fixed it. It almost sounds like there is too much current being pulled through the EFI relay causing the contacts to to stick (almost fuse together). So when you turn off the ignition everything on the circuit stays running keeping the relay stuck. When you pull the relay, it cools and the contacts finally seperate. My advise would be to find everything drawing current from that relay, see if anything can be temporarily disabled to lower the operating current to test my theory.
Come to think of it I may have had the greddy e-manage drawing off the same circuit when I was having my sticking relay problem.
It can be only one of two things the switched voltage/ground the turns on the EFI relay is not switching with ignition or my EFI sticking theory.
Come to think of it I may have had the greddy e-manage drawing off the same circuit when I was having my sticking relay problem.
It can be only one of two things the switched voltage/ground the turns on the EFI relay is not switching with ignition or my EFI sticking theory.
03-14-11, 03:47 PM
#25
i swapped ECUs with a friend (who also has a 99 sc300), and the efi relay did not get stuck on. it went on/off with the key with a short delay, as it should.
so my ECU is bad.
now i have to get a used one and figure out how to reflash it to use my key
so my ECU is bad.
now i have to get a used one and figure out how to reflash it to use my key
03-16-11, 07:02 AM
#26
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Did you do a current draw test with your friend's ecu to compare the difference from yours.
Are there online schematics for the SC300? Looking at the SC400 schematics on page one it looks like ignition switched voltage goes to the ecu, the ecu then grounds the EFI relay sending voltage to the main circuit of the ecu(powering it on). Not sure why this would be set up this way unless it gives the ECU a way to turn off the EFI relay after an accident or for part of a theft deterrent system.
That being said either the grounding circuit of the ECU that swithes the EFI relay is bad(ECU needs repaired), ignition switch is not switching IGN power correctly, or too much current is causing the EFI relay contacts to stick(which could be a defective ecu or something that has its power run through the ecu like injectors, etc.) .
Are there online schematics for the SC300? Looking at the SC400 schematics on page one it looks like ignition switched voltage goes to the ecu, the ecu then grounds the EFI relay sending voltage to the main circuit of the ecu(powering it on). Not sure why this would be set up this way unless it gives the ECU a way to turn off the EFI relay after an accident or for part of a theft deterrent system.
That being said either the grounding circuit of the ECU that swithes the EFI relay is bad(ECU needs repaired), ignition switch is not switching IGN power correctly, or too much current is causing the EFI relay contacts to stick(which could be a defective ecu or something that has its power run through the ecu like injectors, etc.) .
Last edited by MAJones; 03-16-11 at 07:35 AM.
03-16-11, 07:36 AM
#27
i did not test the current draw, but it seems to be somewhere around 1amp, as that's what others have tested that have had this problem, and it takes my battery about the same amount of time to drain.
on the 98+ SCs, the ECU gets constant power at the BATT pin (from the efi fuse). the ignition switch sends 12v through the 7.5amp IGN fuse down to the IGSW pin at the ECU.
the ECU then turns on the EFI relay to power all the sensors, fuel pump, etc.
the FSM says that toyota did it this way so that the ECU could be programmed to leave the sensors on for 2-5 seconds after the engine is shut off, so the ISC and some other things can return to the correct position or something.
10-28-11, 11:16 AM
#30
Start the car , run it for about a minute and put your ear close to the EFI relay. Have someone turn the car off and listen to the relay. It should turn off about 2-3 seconds after the engine and ignition fully turned off.
Come back and let me know.
Come back and let me know.