How is the ignition switch connected to the starter solenoid

[ww1dm1]

Quick question for those familiar with the starting system on the x40. Which one of these is correct:

A: Ignition switch is connected straight to the starter solenoid and full solenoid current goes through the switch;
B: Ignition switch is connected to the starter solenoid via a relay and only a small relay coil current goes through the switch.

I think there should be an inhibitor relay that receives the full current for the automatic gearbox but I am not entirely sure if it applies for the manual gearbox version. What about the immobilizer, does it completely disconnect the starter circuit? There should be a relay then, unless something else is disabled instead and the engine is spun even when immobilized.

[martin93]

Pretty certain the answer is 'A' on a manual gearbox, since the whole idea of the solenoid is to reduce the current anyway. Also, if mine 'immobilises', the starter will still operate but the engine won't fire.

I'm interested now. I'll have a look at the wiring diagram and report back..

[ww1dm1]

Alright, that makes sense. I looked at the Haynes diagrams myself, there is an inhibitor relay marked. However the big question is whether a manual has one or an equivalent for it, since it's only really required to check if the automatic gearbox is in park/neutral if the immobilizer does not disconnect the starter solenoid.

[canis]

I think (if I remember correctly) the engine will turn over but fail to spark on the odd occasion when I've confused the alarm system. So I'd expect the solenoid current to go through the key switch uninhibited.

And it makes sense, really, since hotwiring the starter motor is a cynch. And even easier if parked on a hill. Actually, inhibiting the starter motor would be a crap way to protect a car from theft, so I'm betting on 'A'.

[cheshired5]

Is a starter fuse and/or relay listed in the owner's manual?

[ww1dm1]

Originally Posted by cheshired5

Is a starter fuse and/or relay listed in the owner's manual?

I'm not sure, my owner's manual is in Italian. However there is no fuse named "starter" under the bonnet or under the dash. Only a 40A "ignition switch" fuse, which probably confirms that the solenoid gets it's current straight through the switch.

[cheshired5]

Originally Posted by ww1dm1

Only a 40A "ignition switch" fuse, which probably confirms that the solenoid gets it's current straight through the switch.

I would say that it definitely confirms it.
What else would need 40A in that area?

[bobthecabbage]

There is no fuse on starter motors as a rule. They draw too much current.

Maybe 200 amps for a beefy starter.

The starter solenoid itself I wouldn't expect to draw more than 1 or 2 amps, maybe 3.

Ignition type switches are capable of handling surprisingly large amounts of current. Obviously 40 amps in this situation which is probably divided up between the various electronic modules, the radio etc with anything high current relying on a relay. The old cube shaped relays typically handle about 30 amps.

[ww1dm1]

Originally Posted by cheshired5

I would say that it definitely confirms it.
What else would need 40A in that area?

Exactly what I'm thinking.

Originally Posted by bobthecabbage

There is no fuse on starter motors as a rule. They draw too much current.

Maybe 200 amps for a beefy starter.

The starter solenoid itself I wouldn't expect to draw more than 1 or 2 amps, maybe 3.

Ignition type switches are capable of handling surprisingly large amounts of current. Obviously 40 amps in this situation which is probably divided up between the various electronic modules, the radio etc with anything high current relying on a relay. The old cube shaped relays typically handle about 30 amps.

We're talking solely about the starter solenoid here. I found out that a typical starter solenoid can draw up to ~10A in it's normal operation, with a spike of up to ~30A as it engages. So a 40A fuse seems perfect.

A it is then!