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2012 corolla no ecu after accident

Quick intro. I am helping a friend who was handed a project and I’m at the point I feel it’s a bad ecu.

I have power to everything in the car except when I turn the key to acc and on. Nothing changes. No instrument movement no information from the ecu. Lights dings etc are present when I put the key in and the doors are open. Power has been traced and grounds have been checked. I have power on 2 pins at the ecu and the grounds are good. There is just no communication. Anyone like to concur or offer up another idea before I pull the ecu?

I doubt the ECU is defective from what you stated about the problem. It seems power is either not getting to the ignition switch or there is a bad connection to the switch. First thing to do is verify that all the fuses are getting power through them in the panel under the hood. You should have at least a test light probe to check for power. If the fuses are okay then

The car was in olvedbin an accident into the front left corner they replaced the fuse box up there. But as I stated before fused seem to all be ok the ignition switch has power and identifies that the key is in and the doors are open.

I think the key chime is activated by the key making a ground connection in the key lock mechanism, power to the ignition switch is a separate issue from that circuit. If you are depending on the chime as signs of power through the ignition switch you can be off track. What you described in your first post, things like no warning lights turning on, says to me power isn’t getting through the ignition switch for some reason or there is a blown fuse in the dash fuse panel that supplies those areas power that has to pass through the ignition switch.

I will do some more digging tomorrow. To see why else may be wrong. Ecu input wiring has 0 volts with the key off but with the key on it has 3 terminals with +12v which caused me to lean to it as the culprit. Maybe I’ll tear into the column and look at that as well.

Check to see if the fuses in the dash fuse panel are getting power with the key in the ON position. You can use the small slits on top of the fuses to check for voltage. If those fuses are getting power then the ignition switch is working. The problem is after the dash fuse panel. The first circuit to check is power to the instrument panel.

Will do. Thank you.

I don’t understand this at all. A 2012 should have full coverage insurance so why are you working on this thing anyway. If repair was done and there are still problems contact insurance.

This also is covered by the rule " No good deed goes unpunished ".

Don’t know anything about it but is it possible the ignition switch itself was pushed out of adjustment in the crash? If it is mounted on the column.

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Sorry. I didn’t know the whole situation until late this afternoon. So the guy my friend “works” for buys these cars at auction fixes them up and then sells them. Not sure but my friend had walked into the pickle, still not sure why he did it, but I’m just trying to help him out. We both were in dire need for the cash so why not right… yes I’m rethinking helping him but I already had committed.

As to the switch. I will open up the column and take a closer look at things there tomorrow.

There is absolutely no dishonor in being truthful and telling someone that you are in over your head and are concerned you may do more harm than good.

Check the power to the dash fuses first before digging into the column. If power is getting to them then the switch is okay, at least the ignition side of the contacts. The ACC contacts are separate but ties to some of the fuses in the dash also. If all the fuses are getting power then the switch is good. The trouble may simply be a connector to the dash fuse panel is loose. The same goes for the panel in the engine compartment. Make sure the connectors are pushed in fully.

wrecks often . . . often . . pinch, slice, cut, scar, and otherwise harm wire harnesses.
you may soon be following miles of wire.
when the car is running when wrecked . . Pinched harness WILL short circuit many things, even destroying modules and computers.

A new or used fuse box might not have already in it, all the fuses that this car did, depending on its feature and accessory list.

Very true… once I’ve exhaust these options I may have to break it to him that I’m out of ides.

Since the trouble isn’t intermittent it should be fairly easy to find. Power isn’t getting to cluster it seems and also to the starting system and possibly ignition areas. If the fuse(s) to those areas are getting power to them the trouble is most likely a common problem to those areas after the fuse. Like a connector at the fuse panel being loose. Just follow the power path to the area having trouble using a test light or meter to check for power. Having a wiring diagram for the vehicle can be priceless to have on hand for reference to.

Power usually comes first from the panel under the hood, through the ignition switch, then to the dash fuse panel and on to the individual circuits. Sometimes relays are involved so it could possibly be a relay isn’t getting activated.

Be sure to eliminate the ignition switch as the problem before tackling the computer. I own a Corolla of earlier vintage and had to rewire a work-a-round to correct a faulty ignition switch. On my Corolla it doesn’t take much to expose the ignition switch connector and then back-probe each of the terminals with a multi-meter to see if the voltages are going to where they are supposed to go as you turn the switch to the various positions. On mine, I was having trouble with the start position. The other ones continue to work. To do this properly really requires a copy of the ignition switch wiring schematic.

With a problem like this the first thing I like to go over is a factory wiring schematic.

When it comes to electrical issues I often spend a few hours in the evening sitting in a recliner and poring over wiring diagrams before wading into chasing down electrical gremlins.

Are you saying that when you plug in an OBDII scan tool it doesn’t communicate with it?

Correct. There is power the scan tool powers up there is just no communication.

When you check for voltage on various circuits, what are you using for your ground reference?