ECU power wire short?

[gotsomegetsome]

hey guys, so the other day i was trying to install a new gauge I bought
when I was messing with the wires, I dropped one on the other by accident and now I dont have any power to the ecu...or so i think

I have an safc2 hooked up, and that will not turn on.
this is why i think its the ecu power wire that has shorted out
I checked the fuses and all are fine, but im worried about the efi main relay

do you think i blew the efi relay? or is it just the wires....
any suggestions? haha besides to not short out wires

 

[sneakypete]

have you checked the main fuse bus (or whatever its called) in the fuse box under the hood? its the bigger blue fuse looking thing. ive popped that one before and it took me a while to figure out that it blew...

 

[gotsomegetsome]

no i checked that completely
every single fuse in there is fine
which is why im confused

ive narrowed it down to this, the negative ground wires that run to the ecu are fine but the positive is not receiving any power, so it much be between the 10 amp ecu fuse and where i have the wire cut

has anything like this happened before??

 

[Nick M]

Do you have a check engine light? Put your key in the ignition, and turn it to run, but don't start.

 

[gotsomegetsome]

yes that is what happens
to start the engine i have to run a power wire from the positive battery connection to the ecu directly

do you think it may be another fuse?

 

[3p141592654]

Do you own a multimeter and know how to use it?

 

[dumbo]

Do you own a multimeter and know how to use it?

Good choice of words

I didn't understand, you do or don't have the CIL with key on, engine off?

 

[gotsomegetsome]

I didn't understand, you do or don't have the CIL with key on, engine off?[/QUOTE]

CEL? no check engine light, no power to ECU.

Do you own a multimeter and know how to use it?

are you refering to continuity? .... it's pretty strait forward. No continuity = no power transfer through wire = ecu and thus ignition does not turn car on, not crank, but not even on. aside from the accessories, nothing turns on

so back to anything relevant to my question, are there any fuses or potentially weak parts in the wiring that I can pinpoint that arent located in the fuse box, unless the efi main relay is blown?

 

[Nick M]

You can't run a continuity test through a power wire.

And if you unplug everything, you can drop 12.5 volts, yet show zero ohms on the continuity test. Not to be confused with the reading O_L.

Have you looked in the EWD yet? It shows pin out voltages with the key on and off, at all spots. Then you will see when you are to get power to the ECU.

Yes, there are several fuses that need to be checked electrically.

 

[dumbo]

Get reading...if you know how to use a multimeter. Trust me its relevant.

http://cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?S=FI&P=1

 

[3p141592654]

Okay, since you didn't answer I'll assume you have one and know how to use it.

You need to get access to the ECU and confirm (with your DMM) that you have 12V at the BATT terminal. I don't know what year you have, but it is probably connected to the main relay via a black-yellow wire.

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


Post back your results and we can continue (or not) your call.