no power to ecu

[maxburn]

Hey guys I accidentally connected b+ and te1 when going to check codes and now I don't have any power to my ecu. It popped the efi fuse and that's it I checked the rest of the fuses in the kick panel and they're all fine could I have fried my ecu? It was running fine until this. What do you guys think I need to do to fix this? Thanks for any help guys.

 

[maxburn]

Bump. Any thoughts guys?

 

[7M4EVR]

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=49

 

[maxburn]

Hey guys I checked for voltages and this is what I got at the ecu
B+ 1.5v-1.59v
batt -.4v
+B1 11.31v
IGSwitch 0v
e1 0v
e01 0v
e02 0v
m-rel -.2v - -.4v
FC -.2v
FP 4.85v

I'm not getting any power in the diagnostic box all fuses are fine and are flowing power. Efi main clicks when turned to on. Where would a good place to go from here be?

 

[hvyman]

Are those voltage with the key on?

I would double check all your fuses.

Igsw should have 12v with key on.

 

[jetjock]

^ That, although it's more telling the Keep Alive is dead...

 

[hvyman]

Ya.

Also b+ and b+1 are the same wire and should have identical voltages.

http://www.cygnusx1.net/supra/Library/TEWD/MK3/manual.aspx?S=Main&P=49

 

[maxburn]

This is with the key on and just checked again on the fuses they look to be good and seem to be seating well. I don't understand why I'm getting negative voltage on a couple and the voltage disparity on B+ and +B1. What's the keep alive?

 

[hvyman]

If you hook the leads up backwards it will be negitive.

Ecu will not turn on if the igsw doesn't give it a signal.

How are you checking the fuses? By looking at then or with a volt meter?

 

[maxburn]

I checked them all with a volt meter. When I checked all of the ecu pins I did it with the same leads each time positive to the pins and negative to ground. Should it have been done differently on m-rel and batt?

 

[maxburn]

I wanted to add that the ignition switch is turning everything else on in the on position such as all the other check lights on the dash just not the cel. I don't know if that makes a difference or not. What would my next step be? Trace the wire through the loom checking for burned spots or would it be a component?

 

[jetjock]

batt -.4v

 

[maxburn]

Update: changed the circuit opening relay now I'm getting
B+ 11.3v
batt 0v
+B1 11.31v
IGSwitch 0v
m-rel -.02v
FC 0v
FP 4.85v
I'm getting fuel pressure and cel but no spark now. Still no power to batt ignition switch and m-rel and still no power through diagnostic box what so ever.

 

[3p141592654]

Shorting TE1 to B+ would not do anything bad. Batt must be 12V all the time.

 

[maxburn]

If it wasn't that are there any terminals in the diagnostic box that could have been shorted that could have caused this instead?

 

[7M4EVR]

Ur just missing it man...lol.

Batt voltage is no bueno!

 

[jetjock]

What's the keep alive?

Your ECU needs to remember things. Things it learns (idle, spark, and fuel control) and things that happen (faults and codes). This data will be lost when the ignition switch is turned off unless the box is kept continually supplied with 12 volts. Such connections are generically known as Keep Alive. Toyota calls it BATT because it's connected directly to the battery through the EFI fuse (hence "resetting" of the ECU by pulling that fuse) and because, well, they're Toyota. Anyway, you appear to be BATT-less...

 

[maxburn]

:icon_biggLooks like it's was a combination of a bad fuse block causing an 8 volt drop and a loose pin or 2 on the ecu plugs. Glad to have my car back on the road:icon_bigg