Potential Imobiliser Problem

[MrMCI]

Hi Chaps,

It has been a while as I've had a good few years of zero problems but I think I've developed a new one.

Basically my car has been getting harder and harder to start with the starter solenoid "machine gunning" before finally engaging, made worse when the car has been left for a week or two but fine when warm. Over the years I've had multiple batteries, new power and earth cables and a new starter but I think I've finally diagnosed as a problem with the grounding wire from the hot start relay, without spelling it all out, is this part of the imobiliser circuit? I've also noticed the alternator doesn't charge until the car has warmed up too. I guess this is the 12v excitation feed but I don't see the warning light at any point. Could this be connected and does anyone have any solutions?

thanks in advance.

Mark

[QBee]

The "hot start problem" as I am sure you know, is when it won't start hot. Been there, had that.

Your problem - well, I would be taking the starter motor and solenoid off and getting them checked over - or replaced.
From your description, the problem sounds mechanical rather then electronic.

[MrMCI]

thanks Q Bee, definitely not mechanical as I can create my own earth to the negative side of the hot start relay, independent of the alternator then she starts a treat.

[Aussie John]

And I thought Quinny gave a lifetime warranty!!!!!!

[Quinny]

Aussie John said:

And I thought Quinny gave a lifetime warranty!!!!!!

It ran out on the 21st of March 2019

[blitzracing]

Do you have a charge light to start with on a stationary engine? This is what supplies the excitation current to the alternator and so it goes out once the alternator is producing more than the battery voltage- and no its not part of the immobiliser circuit. As for the tommy gun sound- its simply the voltage on the back of the solenoid is dropping once the starter is engaging and drawing more current, so the solenoid drops out, and with it the voltage recovers, and the cycle repeats. The hot start kit is nothing more than a relay, but in its own right does not draw a lot of current but you would hear the relay click with the starter if the hot start relay coil is suffering the same drop out voltage via the immobiliser or ground wire. You can try some simple tests- put a test meter from the negative of the battery to the engine block, and crank the engine- any significant voltage means you have an earth problem. Put the test meter from the battery positive to the solenoid and crank- any significant voltage means you have an issue with the immobiliser or hot start relay contacts. You will see the battery voltage on the meter when you are NOT cranking as the meter is grounded through the solenoid, but this should drop to near zero as you crank.