I was messing with my ecu by installing a circuit. Now, when I try to start my car, all power disconnects. I disconnected the circuit already. I have to reset my ecu to get power when on ACC. But every time I try starting it, power cuts off. I hear a click from the starter, but barely. Anyone have any suggestions?

 

Replaced my ecu already, didnt help

 

What circuit? My Gf's sc300 died the other day driving, the cluster doesn't light up, only the cel and oil and door open light. They go off when the key is out. Then come back on when I turn the lights on with no key in ign. I was stupid and tried to run the stereo to +B and batt. Haven't undone it all yet. If you tied into similar stuff we may be on the same path. Side note, I recently replaced caps in the ecu that were fried.

 

Will the horn beep? Will the headlights burn? Try cleaning the connections at the battery, it may be a coincidental loose connection at one or both battery terminals.

 

I made a circuit using a ripple counter to convert the frequency of speed sensor 1 to work for speed sensor 2, it didn't work obviously. I connected the ripple counter(chip) to sp1+ and sp2+. After resetting the ecu(pulling out efi fuse) I have all power, horn, all lights, dash, everything works normally, until I start the car, then all power cuts off, nothing works then.

I tried bypassing the power main relay by Jumpering it, this way I could check if the theft deterrent was the problem since it's connected to the starter relay...but same issue so it's not that.

Then I just jumpered the starter relay and the starter would crank but the engine didn't start.

It's just weird that the power would cut off when I try starting. The starter only works for like half a second before I lose power.

 

So I tried to jumper the starter relay again and the engine still would not start, after I did this I noticed that my instrument cluster back light and needles went out and oil light came on. So it seems like more things are messing up after I tried jumpering the starter relay.

Should my priority be on trying to get the engine to start by jumpering the relay?
or find out why power gets cut when I try starting using the key?