1990 7mgte ECU not being recognized by car and car wont start

[pattywaggon]

This happend to me a few weeks back when i first got the car
its a 1990 7mgte M/T and the car randomly doesnt want to start

when the key is in the "on" position all the dash lights blink besides the CEL light
which means the car isnt getting signal from the ecu

i checked that the dash light works and it does, the ecu has power and a good ground

i have another ecu that i use with a maftpro and the car didnt recognize that either, so its not the ecu and i know 7m ecu's dont go bad


just wonering if other had the same problem

last time this happend i took the ecu out to buy another online but i put the ecu back in to run a few tests and randomly the ecu was recognized and the car started and ran for about a month till yesterday

the ecu was out of the car for almost a day the last time this happend

im going to run a few diagnostic tests today and disconnect the battery to reset the car



Any input is highly appreciated,
Thanks,
Patrick.

 

[D.J.T.]

Does the engine turn over?

My supra didn't have a battery for over 6 months & the ECU worked fine & still does. Make sure THAT ANY of the wires going to the ECU aren't shorting out somewhere. That usually fries it.

 

[Chambers]

Check your voltage at the 7.5A IGN fuse in the driver’s side kick panel, you should be getting 12v when the key is at "ON" if that doesn’t get 12v then the ECU will not turn on, and the CEL will not illuminate.

 

[dubsupra209]

this happened to 1 of my buddys do you have a turbo timer?

check your ignition wire make sure it has power

 

[pattywaggon]

it was the ignition wire
i ran a few tests and realized i didnt have ignition power, the main relay was fine
odly the last time i fixed it was by removing and reinserting a few fuses

the 7.5 fuse was fine, but was heavily corroded
swapped out with a new fuse and all is well.

Thanks for the fast replys

 

[dubsupra209]

it was the ignition wire
i ran a few tests and realized i didnt have ignition power, the main relay was fine
odly the last time i fixed it was by removing and reinserting a few fuses

the 7.5 fuse was fine, but was heavily corroded
swapped out with a new fuse and all is well.

Thanks for the fast replys

thats crazy had same problem with my buddys for almost month no blown fuses swaped engine harness, ecus, coil packs, igniter, cps, just about everything we could think of..

glad it helped