Testing a ecu

Hey guys new to the forum here just picked up my first toyota its a 97 with the 2.7. picked it up cheap the po had hooked the battery up backwards. so far ive found a blown alt fuse and a blown efi fuse replaced both. No fuel pump swapped relays with no change. So im wondering if the ecu has got fried. is there a specific way to test it? Do i just need to remove it and go after it with a meter? Im trying to avoid just throwing parts at it. i will be removing the bed for other repairs in the next day or so and plan to check the pump then to see if its getting power and not just a bad pump its been sitting for a few months now. Any insight or tips would be greatly appreciated

 

@Speedytech7 @BartMaster1234 @mechanicjon

 

Rare to see ECU's damaged by backwards boost. I've yet to see it on a Toyota and I've seen many backwards boosts in my experiences.

You need to keep checking fuses and possible inline fuses.

40A AM1 fuse is critical and from there making sure the ECU fuse has power. Simple test light will check every fuse in minutes

 

The fuel pump will only start pumping after the engine cranks. Once the ECU sees the crank signal it will fire the fuel pump up.

 

I reverse jumped my 5-lug too and fried the same fuses. I fried the main I think 60A power fuse, EFI fuse, radio fuse, and horn fuse. I replaced those and it worked fine.

I don’t think you fried the ECU but there’s a chance. Double check the fuses and relays under the dash and in the engine bay.

 

Thanks for the info. All i have messed with is under the hood in the relay/fuse box where are the inline fuses located and does anyone have a schematic on the under dash fuses my cover is missing im gonna try and pick up a haynes or chilton manual on it for the wiring but they usually leave alot to be desired also not mentioned in the op the cel is staying lit with the key off any idea on that searched on it with no luck

 

Idk if 04 is different then 97 but here

 

May or may not be but it gives me a starting point thanks for the pic

 

Here's a pic of the one from my 96...

 

You probably fried the IGN fuse.

 

I am guessing you hauled this home.

So having no idea what all might be wrong before the little battery mishap.

I wonder is something grounding back through the cel circuit causing it to be lite.

 

Pdf file should tell you how to check ecm power

 

so far i have checked all the fuses and they all check. I havent got to check the ecu yet but im leaning to a short in the ignition. Like i mentioned earlier the cel light and now the a/c switch indicator light stay lit with the key out and my temp gauge pegs as soon as the key is shut off. If i pull the ign fuse in the dash and put it back they all go out untill the key is turned back on. Thats all the further ive got so far any insight would be much appreciated

 

Well its alive and running and i dont know how or why. when i got the truck it gad a cheap obd2 reader plugged into it didnt work so i trashed it no big deal. come to find out for some reason this truck has to have a reader plugged in to run i have one of the cheap bluetooth ones i figured id hook up too run codes plug it up cel is on but no codes crank the truck and it fires up. Im stumped on this one has anyone had this issue before?

 

I know this is a zombie thread but that sounds crazy. I wonder if anyone has any input on this.
I am very curious.