Remove key and engine runs on

[Iain]

Any ideas where to start looking for this problem?

Engine starts on the key fine, but if you remove the key while it's running the engine carries on running. Tested the ECU ignition live wire and get the following:

Ign off 0v
Ign on 12v
Engine started/running 14v
Ign off 14v

[JaysNova]

Could be a slight connection problem behind the hazard switch as i had this problem but wasn't constant

[Iain]

D'oh just sorted it, a relay was sticking causing the ECU ign live to keep 12v.

[MK999]

That was quick for finding a sticky relay, you can look at my diesel if you like lol

[AlexW]

I told him to do it.

[Iain]

Alex didn't help at all :)

[Iain]

Hmm this is still happening. It worked fine when I bypassed the relay, however I have fitted a new relay and it is happening again.

Basically I have an existing ignition live feeding a relay. The relay input is a fused positive and output is to my ECU ignition live.

Key out 0v, ignition on 12v, key out back to 0v
However when its running it doesn't go back to 0v when the key is removed

wtf?

[Adam]

Got to be something do with the alternator id guess with it staying powered once the engine is running.

Whys your ignition live wired through a relay anyway?

[AlexW]

Hes got it so there is one perm live coming in, switched by a existing ign live, and then running lots of things off that one relay, so no worry about load.

Which is fair enough, But I wouldn't run the ecu ign supply like that.

[peester]

correct relays being used?

[Iain]

Yep just as Alex said, I have multiple ign live circuits running off the relay straight from the killswitch.

I've wired in the relay correctly AFAIK, done the same as I have for the air horn and that works OK.

[16v Nova Kev]

this happened to me. in my case it was dodgey copper track on the clocks.

[Iain]

I'll try it without the clocks, worth a shot.

[AlexW]

That is not your problem.

[novarobbo]

i had a problem with my astra td and it was alternator related

[Iain]

Here's some more test findings, think its something to do with the way I've wired the relay as if I connect the new ign live wires to the old one it all works fine

Pull original switched live off relay during "run on period" and engine stops

Measure original black wire during "run on period" and its showing 4v and new output is showing 12v

wtf is going on?
I have the relay wired up as follows:

http://www.mp3car.com/vbulletin/imagehosting/12527647e9129233622.bmp

So

30 = to battery (via fuse)
87 = to output (ECU ign live)
86 = Ground
85 = Original ign live wire

[L14MNP]

Unless you have typed that wrongly, 85 and 86 are the wrong way around.

[Iain]

I've tried it both way rounds, thought it was interchangeable?

I've semi resolved it now. The ignition live I was using was the one that originally ran to the front of the car, I think it was for the coil? This looked like it was actually unfused and split from various other black wires on the bulkhead...?

By running this one directly to the ECU ignition live (through a fuse) and using the fag lighter ignition live on the relay it seems to work.

Can anyone explain why this is?

[Adam]

The way youve got the relay wired is fine. Personally I wouldnt of done it like that, but it should work fine.

And its better how youve wired it up now, with the ecu directly to an ignition live instead of through a relay.

[Iain]

Frick knows why it was behaving weirdly then. Any ideas where I should take a new ignition live from for the relay? Just anywhere as it won't be adding much load?

[Adam]

Yeah, just to switch the relay isnt going pull much amps, so just any ignition live with a ok wire size. Have a root around in the fusebox lol

Headunit ign live?

[Iain]

OK yeah sorted one cheers