I took the weak battery out to slow charge it's reading 12.6 now going to leave it on till later today want 12.8. I put another good battery in the car turn the key and nothing no click from the starter, no dash lights, no door open chimes nothing. Looks like the problem just got bigger wallet with the owners books is empty, know my way around the 1994 and up Jags anything older not so much. The car does have a after market head unit with big *** amp in the boot to complicate things even more....Help

 

Look at the positive terminal cable is there a plastic socket in the cable about 6 inches from the end you can push together?

 

Yes snugged the cables up in the plastic socket will test when the battery is good to go..noticed the battery isolation red switch in the boot below the battery. Where is the button to shut off fuel forgot where it was on the xj6/xj8.

Thanks

 

Inertia switch? Front footwell one side or other usually