Starter motor spins faster with lights on!

[Goatherder]

I’ve had my 500 for a few months accompanied by the notorious hot start issues despite being fitted with a Cobra alarm/immobiliser, now somewhat improved by a 40mm2 starter cable I fitted, however I have recently noticed that the starter motor spins quite a bit faster with the headlights on! can somebody explain please?

[David Beer]

Goatherder said:

I’ve had my 500 for a few months accompanied by the notorious hot start issues despite being fitted with a Cobra alarm/immobiliser, now somewhat improved by a 40mm2 starter cable I fitted, however I have recently noticed that the starter motor spins quite a bit faster with the headlights on! can somebody explain please?

The fat cable to the starter does not cure the hot start, unless it was completely rotten. It can increase the crank speed though. As for it spinning faster with the lights on, some sort of earth problem ?

[Steve_D]

Just had a scan of the circuit diagram and can see no logic for this. There seems to be no connection between these functions.

Have you tried both conditions whilst the coil is disconnected? This will remove the possibility the engine start is being hindered when the lights are not on.

Steve

[spitfire4v8]

how do you know the engine spins faster with the lights on? have you measured it ? sounds can be deceptive.

[Goatherder]

The audible difference is similar to when you change your old knackered battery for a new one, however I have been playing around and now 8 times in 10 it’s slow and the other 2 fast without the lights,
Battery in good condition, and starts fine cold

[David Beer]

Goatherder said:

The audible difference is similar to when you change your old knackered battery for a new one, however I have been playing around and now 8 times in 10 it’s slow and the other 2 fast without the lights,
Battery in good condition, and starts fine cold

Sorry can you explain again, that doesn’t make sense !

[TarquinMX5]

Are you saying that the headlight comment is now irrelevant; out of ten starts, eight had 'slow' starter and two were faster, ie generally slow, occasionally fast?

Were the 'faster' two consecutive?

Have you checked your earth connections.