Another non starter

[kerryxeg]

I jump started the car a couple of weeks ago - it ran ok and restarted ok. Since then it has been sitting on the trickle charger. I took it out today and tried to start it - battery was very flat - the trickle charger is probably knackered.

I put the fancy black and decker charger on it - which rapid charges from zero. A few hours later the charger indicated nearly a full charge and battery in good condition.

I tried to start it, no pump noise no cranking but could hear a relay ticking behind the seats. I swapped the relays around (there are 3 in the panel bhind the seats) to see if I got a different result. Revcounter now blips and the pump runs but no cranking, sometimes a relay clicking. The alarm blip also sometime goes off when attempting to start

I should say it's an S1 Exige VHPD with an emerald. I've not had any issues with the emerald and the alarm since it was fitted. But I did a non start event last year heading down for Amp 3 - stopped in Dundee for fuel and a very similar issue. After 20 mins sitting trying a few things it just started.

All thoughts welcome

[robin]

You can force the starter to turn by using a wire ...

First turn on the ignition so that the fuel pump primes. Handbrake on, neutral, you've been warned

Now looking at the back of the starter (which may be hidden by intake air pipe work on the Exige?) identify the spade terminal with a wire pushed on it ... it's normally the one at the 6 o'clock position if looking from the back of the starter. Now identify the stud with a bunch of thick red or brown wires running to/from it. This is the one at 3 o'clock if looking from the back. Now remove the wire from the spade terminal, use a length of wire to short the stud to the spade terminal. This should make the starter clunk and turn the engine over. If everything else is in place, the engine will start.

I suspect your alarm/immob battery has gone flat and the secondary immobilisation function is preventing the engine from cranking. You might find it trickle charges from the main battery and starts to work again.

You may also have a dodgy start relay or a dodgy starter - if the engine turns with the above bodge then you've got a working starter so time to look at the start relay and the immobiliser. I can tell you how to eliminate the primary and secondary immobilisation function if that turns out to be the problem.

Cheers,
Robin

[Sanjøy]

Mice might have been munching ?

[kerryxeg]

Thanks Robin, I'll have another look tomorrow and do some more detailed checks. I didn't know there was a battery back-up in the alarm - this could be the issue and would explain the previous event. As would a sticky relay.

I believe the door, bonnet and boot contacts are also routed into the alarm system - could a bad contact on one of these cause any issues with the immobiliser?

Sanjoy - I'm pretty sure the garage is mouse free - there are a couple of traps for them and much more interesting stuff to chew which would be noticeable - but you never know.

[robin]

Pretty sure there is a battery on the Exige variant too - it's what allows the alarm to sound when you (or a robber) disconnect the battery without clearing the alarm first.

[kerryxeg]

So I had to move the car today and spent a few minutes on it to see if I could figure anything out.

I checked the inertia switch, which did seem to click? It has gone off before once on a bump, but that shouldn't happen in the garage

I stuck the charger tester on the battery and it reported 80% charge on its guage (not really sure what that indicates), tried to start, no pump just relays ticking away between the seats. I turned the charger on (delivers 14.8v to the battery) and the pump primed but no firing going on. Rechecked with charger off - no pump priming.

The alarm still seems to set and unset ok in blip terms and has plenty life to wake the neighbours
I put the lights on - all looking too dim to be at 80% charge, so I'm suspecting the battery needs replacing.

Would a semi charged battery that's not working well explain the priming / non priming issue and the non start or should I be looking further.

[r10crw]

Maybe semi charged with bad earths? I guess you tried jump lead from battery earth to the block? I'm away on Sunday for the week but can come round next weekend if you like?

[robin]

The inertia switches always click a bit even when they're not tripped.

If the relays go tick tick tick whilst the ignition key is in a fixed position then there is not enough power available to hold the relays closed (open relays don't use power).

Craig is right - it's either the battery goosed or a bad earth.

You can check the earth easily enough but you need access to the battery which is clam off on an S1 Exige, I think?

Disconnect the negative terminal from the battery. Leave the positive terminal alone. Using a multimeter on it's lowest resistance setting measure the resistance from the negative lead terminal to the engine block. It pays to short the meter out first to get a zero reading - some meters read 0.1 ohms when you short the probes together. You really don't want to see anything higher than that from battery -ve lead to engine block. If you get even 0.1 ohms higher than the short circuit reading you're screwed because the starter stall current is 200A and that gives a voltage drop of 200x0.1=20v which is more than you had to start with, i.e. it won't work.

If the battery/earth isn't the problem then we need to do some more methodical investigation into what's happening. Feel free to give me a call when you're standing over the car scratching your head - 07973 391 393.

Cheers,
Robin

[kerryxeg]

Craig Robin, thanks for the comments. In an effort to minimise the hassel factor for all, I'll try to check the earth as you describe and try a new battery. My electrical skills are close to zero - I'd not be confident that I was testing stuff correctly, so if I don't progress then I'll be in touch. Hopefully the obvious ie the battery will be the problem, I've certainly not had electrical gremlins in the past.

[KingK_series]

Craig Robin, thanks for the comments. In an effort to minimise the hassel factor for all, I'll try to check the earth as you describe and try a new battery. My electrical skills are close to zero - I'd not be confident that I was testing stuff correctly, so if I don't progress then I'll be in touch. Hopefully the obvious ie the battery will be the problem, I've certainly not had electrical gremlins in the past.

Robin is a star, and much better at this than anyone else.... he helped me with exactly this, as described 3/4 years ago.

firstly try jumping the starter [ remove the cable onto the solenoid and bridge the two contacts on the starter] with ignition on and in neutral

I used a file with a wooden handgrip, - you have to push hard onto the two contacts to get this to work, but if the engine fires you know the starter is ok.

the trip switch is in the fuel pump circuit, so if you hear the pump prime that switch is fine

- my problem was a burnt relay in the MFU

- the issue in my opinion is that the original MGF loom is cut into by the much too small gauge wire of the cobra immobiliser circuit, this causes overheating and burn outs in the fuel pump and starter circuits, however the tracks onto the relay board in the MFU narrow as they meet the board - I have had 3 of these burn on 3 different cars now, most recently in december on my 11,000 mile S2!

[robin]

There is no MFRU on the S1 Exige I think - they used discrete relays instead - but not 100% sure on that one.

Cheers,
Robin

[KingK_series]

There is no MFRU on the S1 Exige I think - they used discrete relays instead - but not 100% sure on that one.

Cheers,
Robin

That is absolutely correct on all the S1 Exiges I have built engines into, - however the wire gauge does drop for long runs as the starter and fuel pump circuits run through the immobiliser circuit and I have had those burn.