Focus 2013 Mk2.5 - Key Fob Battery message AFTER battery replacement

[unofix]

8 minutes ago, KevG said:

so question is @Shoxt3r what Focus do you have?

He's not even visited the forum since 26th July 2021.

[KevG]

1 minute ago, unofix said:

He's not even visited the forum since 26th July 2021.

Didn't see the date TBH 😅

[mjt]

3 hours ago, Grampabill said:

the half that holds the battery was face upwards on my desk and the circuit board was in the other half

We had a keyless start Mk3 until last year and your description reminded me that the battery was in a separate half of the Shell, which I'd forgotten. If it's like the one in my screenshot I would carefully check the battery contacts. The four-fingered one that touches the face of the battery is unlikely to be causing the problem although you could gently bend the fingers up to make sure. I would pay close attention to the ones which I've highlighted that contact the edge of the battery and make sure there's firm contact with the battery and the contact fingers stand high enough to make reliable contact with the pad on the circuit board. Also check they're all clean. The tin plating on the contacts and pad can oxidise and cause high resistance (you can actually see the two black spots on the pad in this image). If they need a clean the best tool is a fibre pen but assuming you don't have one you could use the rubber on the end of a pencil.

If that doesn't help I'm out of ideas I'm afraid.

[Grampabill]

23 minutes ago, mjt said:

We had a keyless start Mk3 until last year and your description reminded me that the battery was in a separate half of the shell, which I'd forgotten. If it's like the one in my screenshot I would carefully check the battery contacts. The four-fingered one that touches the face of the battery is unlikely to be causing the problem although you could gently bend the fingers up to make sure. I would pay close attention to the ones which I've highlighted that contact the edge of the battery and make sure there's firm contact with the battery and the contact fingers stand high enough to make reliable contact with the pad on the circuit board. Also check they're all clean. The tin plating on the contacts and pad can oxidise and cause high resistance (you can actually see the two black spots on the pad in this image). If they need a clean the best tool is a fibre pen but assuming you don't have one you could use the rubber on the end of a pencil.

If that doesn't help I'm out of ideas I'm afraid.

Thank you for your suggestions. I did check the contacts when I removed the new battery to clean it with acetone. The one thing I did not check was the inside face of the +ve contact to the battery. I'll give that a shot tomorrow and see what happens.

[mjt]

I hope you'll keep us informed of progress, or lack of.

[Grampabill]

4 hours ago, mjt said:

I hope you'll keep us informed of progress, or lack of.

Still no joy. All contacts cleaned. no obvious dirt or corrosion on any of them. Tomorrow one of my younger friends will carefully touch all the soldered joints with a mini soldering iron that's not too hot and that are easily visible and see what happens.