Fitted a new battery on my 2014 Focus yesterday.

At first car wouldn’t start, wiggled wires around and eventually got car to turn over.

Today started no problem,  went for a short drive on returning to car it wont start again.

Getting engine service due warning 

Called out AA ,guy checked everything over only conclusion he could come up with is that my ECU is goosed but he couldn’t be 100% sure.

Anyone had similar issue?

 

I should add that i cant see how changing the battery could affect the ECU.

46 minutes ago, Chin Bates said:

I should add that i cant see how changing the battery could affect the ECU.

Always assuming it was installed correctly? 

I get what you mean, but im pretty sure i did install properly and given that the AA didn’t detect anything wrong on that side im stumped.

Assuming it has a Start/Stop system:

1. Have you fitted the correct battery?

2. Did you fully charge it before fitting?

3. Did you reset the battery monitoring system (BMS) after fitting?

sorry not sure what you mean by start stop system.

if you mean the engine stops when fully charged in neutral and hand brake on yes it does.

1 yes checked by AA

2 Assumed as brand new battery, was fully charged.

3 Didnt reset BMS , will google how to do this in morning as im currently drowning my sorrows lol

thanks for reply/ advise 

6 minutes ago, Chin Bates said:

2 Assumed as brand new battery, was fully charged.

Assumed wrong. They need to be charged for 12 hours before fitting.

6 minutes ago, Chin Bates said:

3 Didnt reset BMS

Oh dear !  Watch the videos attached:

On 3/29/2023 at 8:13 PM, unofix said:

How to reset the BMS method 1                                                                        

 

 

On 3/29/2023 at 8:14 PM, unofix said:

How to reset the BMS method 2                                                                       

CAUTION: The reference at the beginning of the video saying that the BMS should be reset after charging the battery in incorrect.

The Battery Monitoring System (BMS) should only be reset if a new battery has been fitted.

 

AA report.

may help better than my explanation 

Will try all suggested fixes tomorrow.

Cheers for help

Why did you change the battery?

3 hours ago, Chin Bates said:

sorry not sure what you mean by start stop system.

if you mean the engine stops when fully charged in neutral and hand brake on yes it does.

https://www.ford.co.uk/support/how-tos/more-vehicle-topics/engine-and-transmission/what-is-auto-start-stop

20 hours ago, anon said:

Why did you change the battery?

The old one was on the way out.10 years old original battery.

In which case, I expect that you were already getting lots of random malfunctions anyway.

If manipulating the wiring made it work once, there is your answer. It isn't the ECU, it is a loose connection so take it all apart, spray the connections with contact cleaner, not wd40, ensure that there are no pins pushed back in any connector, then push the cleaned connectors back together making sure they mate fully. Be methodical. The one you miss is the one that failed. It is a bit laborious but better than buying a new ECU and finding that you still have the same fault.

Apologies for not posting for last week but car was in garage under investigation.

They couldnt find the problem and sugested getting an auto electrician.

I went to pick car up today, disconected these wires wiggled about and reconnected.

Car fired up and so far has been ok. Happy days.

puting it down to a bad connection, if it happens again at least i now know where to look.

Thanks to everyone who offered advice. 🍻🍻