Can't START engine, when ignition is ON.

[SheepDog]

Yes, one admin key and 1 additional one that came with the car.

Any damage to the brake pedal switch/wiring from the crash? (the one attached to the brake pedal linkage)

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[SilverUri]

Any damage to the brake pedal switch/wiring from the crash? (the one attached to the brake pedal linkage)

The pedal works without any problems, the car starts and brakes normally, and the impact theoretically had little chance of damaging the cables. Forscan shows no errors.

 

[SheepDog]

The pedal works without any problems, the car starts and brakes normally, and the impact theoretically had little chance of damaging the cables. Forscan shows no errors.

Considering that the knee bolster airbag deployed, it could have damaged stuff in the footwell. I didn't mean the pedal itself, I meant the switch connected to it, that operates the brake lights, unlocks the shifter, and allows the ignition switch to operate

 

[SilverUri]

Considering that the knee bolster airbag deployed, it could have damaged stuff in the footwell. I didn't mean the pedal itself, I meant the switch connected to it, that operates the brake lights, unlocks the shifter, and allows the ignition switch to operate

Interesting lead, I'll investigate. Thanks

 

[shogun32]

Not a crashed gt, but my 200a 6mt starts immediately from "full accessory mode" as long as the clutch is depressed like any other time.

So does my 300a 6mt

It's your car. Be it wire or sensor, or operator error.

I grok the question in the abstract, but if the car starts from powered off, I don't get the fascination with this particular failure mode.

 

[Torched10]

You said it starts if you dont press start button first,so don't see your concern.just step on brake first then press start button that's always the way I've done it even when I had 2 shelbys one six speed.push clutch in press start button car.starts did you replace fob battery

 

[SilverUri]

You said it starts if you dont press start button first,so don't see your concern.just step on brake first then press start button that's always the way I've done it even when I had 2 shelbys one six speed.push clutch in press start button car.starts did you replace fob battery

Thanks. Yes, I replaced the battery, with a new Duracell one. The factory one was broken when it arrived. Half a year of standing on the square killed the original battery. I found a battery with exactly the same parameters as the factory one. Do you think that this is the reason why when the ignition is turned on, the battery will not be able to produce a sufficient spark and the car simply decides to turn off? It would make sense.

 

[SheepDog]

the battery will not be able to produce a sufficient spark and the car simply decides to turn off?

No, but a loose connection might

 

[ORRadtech]

My '18 w/o the digital dash starts from the accessory mode with foot on the brake and a touch of the start button- no long press needed.

I grok the question in the abstract, but if the car starts from powered off, I don't get the fascination with this particular failure mode.

You said it starts if you dont press start button first,so don't see your concern.just step on brake first then press start button that's always the way I've done it even when I had 2 shelbys one six speed.push clutch in press start button car.starts did you replace fob battery

I get it. If it were mine I'd want it to behave as it was intended. It would bother me no end until I figured it out.

Sorry OP, I've got nothing to help. It does sound like shogun32 has a good place to start looking with the under dash wiring. That airbag is suspiciously close to a lot of wiring and connectors that could affect starting.
Good luck.

 

[luca1290]

The factory one was broken when it arrived. Half a year of standing on the square killed the original battery. I found a battery with exactly the same parameters as the factory one. Do you think that this is the reason why when the ignition is turned on, the battery will not be able to produce a sufficient spark and the car simply decides to turn off? It would make sense.

This looks like a very much more graceful shut down that the one produced by a loose connection of low battery, especially if the car operates correctly after you start it.

There is something that some ECU is reading somewhere that causes this behavior that she doesn't like and produces this output.

For the OP, other than comparing the programming with a known good one (what you could do is also reprogram you ECUs with the good one from the factory if you have FDRS and an original VCM interface - I have and I'm sorry we live that far apart!!) is closely inspect with Forscan all the PIDs related to "engine allowed to start" in the PCM and BCM.

I would not try to rule out the possibility the previous owner modified the car to have this exact behavior - be it in software OR hardware somewhere.

 

[SilverUri]

This looks like a very much more graceful shut down that the one produced by a loose connection of low battery, especially if the car operates correctly after you start it.

There is something that some ECU is reading somewhere that causes this behavior that she doesn't like and produces this output.

For the OP, other than comparing the programming with a known good one (what you could do is also reprogram you ECUs with the good one from the factory if you have FDRS and an original VCM interface - I have and I'm sorry we live that far apart!!) is closely inspect with Forscan all the PIDs related to "engine allowed to start" in the PCM and BCM.

I would not try to rule out the possibility the previous owner modified the car to have this exact behavior - be it in software OR hardware somewhere.

I think that the clue to the previous owner may be right, because the entire exhaust and air intake have been redone, not to mention a few changes to the sound system.

long investigation ahead of me ;-)

 

[ORRadtech]

When you check the wiring under the dash be sure to take the time to continuity check each wire related to the start and brake switches. Also check each connector to be sure all the pins are seated fully.
My thinking is that during the air bag deployment and all the other work done something could have been pulled breaking a wire inside its insulation or unsettling a pin.
Do you have a FSM with the wiring diagram
Also, is this the only quirk you have found?

 

[SilverUri]

When you check the wiring under the dash be sure to take the time to continuity check each wire related to the start and brake switches. Also check each connector to be sure all the pins are seated fully.
My thinking is that during the air bag deployment and all the other work done something could have been pulled breaking a wire inside its insulation or unsettling a pin.
Do you have a FSM with the wiring diagram
Also, is this the only quirk you have found?

Good idea, I'll go through all the wiring in a few days. Another interesting change is the additional subwoofer installation, with its own fuse, which was cut out during transport.

I don't have FSM wiring diagram

 

[ORRadtech]

I think you would be well advised to get an FSM for your car. They have tons of information including flow charts for testing and diagnosis of all the major systems (including starting), pin point testing, wiring diagrams, wiring harness and connector routing and locations and pretty much everything to do with the car.
You can find downloadable, searchable versions online starting around $100. There are also services like Alldata where you can find TONS of information starting at (I think) $25 for a 1 year subscription.

 

[Bean_M]

Did you ever work out the cause? I'm having exactly the same problem with my manual 2020 GT. I turn the ignition on to access accessories or change modes, then when I press the clutch and push/hold the start button the car turns off instead. I can start the car when it's off.

No previous crash damage reported and the car otherwise operates normally.

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