So I purchased a 2011 automatic ford focus in May 2022 and the battery light has always come on intermittently.. fast forward to June my car completely cut out I had the aa out they said it was the alternator or the wiring.

I had a mechanic fit a new alternator and then had an auto electrician check the wiring and now the battery light pings on even more intermittently.

 

I've purchased a new battery and the ford dealership have had it for 5 days and have no idea what's causing the issue, they've seen the battery light come on but there not getting any codes and the battery and the alternator are in good working order and they've checked all the wiring.

 

They've said there's nothing they can do.. can anyone suggest what can be pinging the battery light on intermittently?

48 minutes ago, George Pickering said:

I've purchased a new battery and the ford dealership have had it for 5 days and have no idea what's causing the issue, they've seen the battery light come on but there not getting any codes and the battery and the alternator are in good working order and they've checked all the wiring.

 

They've said there's nothing they can do.. can anyone suggest what can be pinging the battery light on intermittently?

I would be checking the soldering of the instrument cluster which is an extremely common problem on a Focus 2011 model.

I'd also expect the a main Ford dealer should be able to find the cause of the fault in less than 3 hours, so I would wonder if the dealership has a MasterTech or if the job has been given to the apprentice.

Could be a cracked mega fuse, located in a compartment on the front of the battery tray, assuming you have a mk3, they can crack but difficult to see, as it can be hairline, also the white wire that feeds the battery monitoring system, can corrode inside the insulation, the bms is a square little box attached to the negative post of the battery, with a white wire that runs to the positive post, I have shown a diagram of the mega fuses.