Hi Robert,

I cannot see it would be your immobiliser if you could boost start the car with the old battery.  When you say boost start do you mean jump leads from another battery?  I would check all ignition connections as the extra boost may be jumping a poor connection.

Alan

Hi,

i assume your car is a V12, so I recommend you find a starter circuit for your model on the internet and view the components involved.  The starter relay is a good starting point and to find the part on your car just ask the question again on the internet. Just look for loose or burnt contacts. You can short out relays to check them out but I would not go there if you not not sure what you are doing.  If it is difficult to find components disconnect your battery and check all visible contacts.  I know this looks to be a bit of an overkill but with old cars I think it is a good process to look for anything that can give you a problem in the future.  I am sorry I cannot be more specific but I have not had this issue with my 3.6 cabriolet.  My job before I retired was to do with domestic appliances and I found that with any electrical issue the first step to use is observation as a poor circuit problem will in many cases show some sign of deterioration, especially high voltage/amps circuits.

Regards

Alan

Hi Robert,

I have an ’88 with the V12. IF you’re car is wired the same as mine- here is something you can check.

The heavy positive cable from the battery comes forward along the underside of the transmission tunnel to the engine compartment.It is connected to another heavy cable that runs from left to right , on the engine side of the firewall. At the RHS of this cable is where the connections are made for your starter.  BOTH ends of the firewall cable need to be checked for a poor or loose connection.Disconnect your battery(or you will have fireworks) and you should find both connectors covered by a rubber boot. You will find that there is more to it than just a simple nut and bolt, there are actually two nuts that need to be removed to clean everything up. A bad connection at either end will kill your starting efforts! Again- IF your car is wired the same as mine………

Robert, I’m glad you are having some success. Based on my own experiences, here is something else for you  to consider.When I acquired my own car, I checked and cleaned all the various connections on the convoluted battery cables.  Went over everything, or so I thought. About a month later, I went to start the car, turned the key to the “start” position, and- nothing. Silence.  On strike!  I tried a few times- not a click. Finally, after maybe six attempts the starter engaged, and the car came to life.

I suspected the starter/ignition switch, and removed it from the car, and opened up the electrical part.The contacts had a coating of slight corrosion , and just needed  to be cleaned and lubricated. Not wishing to be stranded  somewhere, I wired a generic pushbutton switch into the starter circuit, and mounted it under the dashboard, within easy reach. Now I have a back-up. I find myself using the push button to start the car now.

I suspect a “specialist” will advise replacement of parts rather than a repair, but that is for you to decide. Corrosion inside the starter/ignition switch is fairly common, I have discovered.