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The mkiv Supra Owners Club

Car wont start


sarjo

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There's a 30A fuse from the battery feeding the ignition switch. Its labelled AM2 and should be in the fuse box behind the battery.

 

This goes to 'Relay block 2' on the 'left side of engine compartment'. In this block is the EFI1 and EFI2 fuses. I'd put my money on these two, although they are both 30A also.

 

Check all fuses in this block as there may be something not obvious controlled by one of the accessory fuses that could knock out the ignition, especially with an aftermarket ECU.

 

Also check your ECU for additional protection fuses etc.

 

Good luck!

 

 

Tempted to go home at lunch time and check it out, rather than wait for home time. Lets hope this is it . . . thanks K14. Would this really allow everything to work on pos 1 but not pos 2? Fingers and everything else crossed.

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Great in position one - dead in position two.

 

This suggests that the power feed to the accessory terminal is ok, but the ignition power feed is gone. They are 2 seperate feeds once past the AM2 (main ignition feed fuse). Good news is it should be just a single fuse.

 

Looks like the EFI1 fuse in relay block 2.... I hope! :)

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Err, it didn't have the desired effect. My instruments light up in position 2 with all of those fuses removed.

 

Will take another look in the wiring diagrams.

 

Edit: Even with the 50A Main fuse removed everything on the dash lights up in posn 2. Do all your lights go out in posn 2??

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Err, it didn't have the desired effect. My instruments light up in position 2 with all of those fuses removed.

 

Will take another look in the wiring diagrams.

 

Edit: Even with the 50A Main fuse removed everything on the dash lights up in posn 2. Do all your lights go out in posn 2??

 

 

Everything goes off - I'm trying to think, there was one light on the dash that was just very faded, but cant remember if it went off.

 

One thing I didnt try was taking the connections off the nos switch to see if that had any effect.

 

Bllx

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Its difficult to tell what it can be without the car.

 

You'll need to check out all the fuses in the kick panel & the engine bay... after disconnecting the NOs connector as this may be shorting to ground continuously in posn 2???

 

PM me when you get home & we'll sort it out.

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Check:

30Amp fuse, AM2. This is in the engine bay fusebox, 3rd fuse down.

 

7.5Amp fuse, IGN. This is in the hard-to-reach fusebox in the drivers' footwell, top right fuse out of the pack.

 

Both of these run off position 2 on the ignition switch. I'm assuming none of this setup has been changed to fit your aftermarket ECU, and that this ECU behaves the same way as the stocker for power distribution and starting. If either of those fuses are dead then the ECU won't get the ignition switch signal, and subsequently won't switch the EFI Main Relay - which powers up pretty much the whole car.

 

My money is on the 7.5amp IGN fuse :)

 

-Ian

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Check:

30Amp fuse, AM2. This is in the engine bay fusebox, 3rd fuse down.

 

7.5Amp fuse, IGN. This is in the hard-to-reach fusebox in the drivers' footwell, top right fuse out of the pack.

 

Both of these run off position 2 on the ignition switch. I'm assuming none of this setup has been changed to fit your aftermarket ECU, and that this ECU behaves the same way as the stocker for power distribution and starting. If either of those fuses are dead then the ECU won't get the ignition switch signal, and subsequently won't switch the EFI Main Relay - which powers up pretty much the whole car.

 

My money is on the 7.5amp IGN fuse :)

 

-Ian

 

 

How much do you want if it is the 7.5amp?? :D

 

I'd willingly pay it if that sorts it.

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Ian, I've tried pulling the AM2 fuse and the instrument panel still lights up, which goes against what Jo saw. I thought the Ign fuse was powered through the AM2 fuse?

 

And if the dash is not lighting up & its not the instrument panel fuse then???

 

I think there is a little more to this than one fuse. We'll have to see what Jo comes up with.

 

Edited as I can't spell for tofee ;)

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Well, if it's anything particularly odd I don't think I'm going to solve it in one post ;) The 7.5amp fuse is a good place to start and the AEM might be making all the difference for all we know. If it doesn't, there is a raft of things we can try.

 

I suspect I'll have to keep an eye on this thread tonight for a stressed bunny :)

 

-Ian

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Well, if it's anything particularly odd I don't think I'm going to solve it in one post ;) The 7.5amp fuse is a good place to start and the AEM might be making all the difference for all we know. If it doesn't, there is a raft of things we can try.

 

I suspect I'll have to keep an eye on this thread tonight for a stressed bunny :)

 

-Ian

 

 

 

How did you know I was stressed - come to think of it, how did you know I was a bunny :D . In fact, I could turn it into a free weekend vacation in the seaside for you all to come down and sort it :D Bbq starts at 7.30 ;)

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OK - checked all fuses and they seem ok. Tried to start her and:

 

position 1 - everything fired up

position 2 - nothing

 

 

So put it on charge and battery was showing

 

position 1 - everything ok

position 2 - nothing

 

 

Tried again

 

position 1 - everything fired up then slowly things started shutting off, fuel pumps died, radio died, ignition lights died.

 

 

Am I being hopeful or does it just sound like a flat battery. This was a new Halfords battery back in April, but like I said before, with my fuel pump prob car has not moved now for 3 nearly 4 weeks, other than a quick trip down the lane last Sunday.

 

 

Oh, and when I checked footwell ign fuse - it had been changed to 20 amp instead of the said 7.5. Would there be a reason for this or just someone being lazy in the past and replacing it with the wrong one?

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Oh, and when I checked footwell ign fuse - it had been changed to 20 amp instead of the said 7.5. Would there be a reason for this or just someone being lazy in the past and replacing it with the wrong one?

 

 

well i dont know much about supras but if that is the case it cant be good as its risking damaging all the equipment as it wont blow if theres a problem

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Mmm, have you got a multimeter? If so, use that to check the voltage of the battery.

 

That 20amp fuse doesn't sound good - you are sure that you are looking at the IGN fuse, as the top left corner is a 20amp fuse for the wipers :)

 

-Ian

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well i dont know much about supras but if that is the case it cant be good as its risking damaging all the equipment as it wont blow if theres a problem

 

 

Yep - my thoughts exactly. Have changed it back.

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If it blows now you know you have a problem!

 

Just wondering if your aftermarket ECU needs more current?? I doubt it, but its strange there was a 20A in there.

 

Things starting to die does sound like the battery. Give it a full charge overnight and see what it does. You may have a large current drain with the NOs wiring shorting out??? Is that disconnected now??

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If it blows now you know you have a problem!

 

Just wondering if your aftermarket ECU needs more current?? I doubt it, but its strange there was a 20A in there.

 

 

Thats what I was thinking - maybe it needs more. Going to give it another hour on charge and then try again :(

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Now I'm getting really p'd off. Battery showing 80% charged, so took charge off and tried to start her up. Nothing - dead. Went to take valet mode off, nothing, no alarm.

 

Have still got silly things like lights, hazards etc, but thats about it.

 

Checked fuses - all good. (Oh, I was upside down so made the mistake - 7.5amp on ign. :nana: )

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Yep defo won't be the battery as you'd still hear the solenoid click.

 

Not if the battery is fully flat.

 

my old jspec battery completely died, had nothing at all left in it, and that still powerd the dash lights, but not the 'binging' noise when you put key in ign lock. It was so flat that key to position 2 did nothing at all, no solenoid clicks

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