Mk4 ford mondeo - Mk4 mondeo battery connection fail

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Sat 17 Nov 2018 13:22
Mk4 ford mondeo - Mk4 mondeo battery connection fail - S40 Man

What a Muppet. I disconnected old battery and must have twisted it when putting it down. Anyway I put the new one in and got the +ve and -ve the wrong way round. Fans and the horn came on and I disconnected it. I realized to my horror the error I made. Lights and door locks work OK but engine won't start. Anyone got a good idea? Maybe immobilizer is unhappy.

Did I just kill my car??

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Sat 17 Nov 2018 14:07
Mk4 ford mondeo - Mk4 mondeo battery connection fail - hardway

I'd try to scan the ECU.

if you get comms great,

if not then the ECU is fried.

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Sat 17 Nov 2018 14:14
Mk4 ford mondeo - Mk4 mondeo battery connection fail - elekie&a/c doctor

Do you feel lucky? It may be that some fuses have blown. Check those in the engine bay fuse box next to the battery. There is a low rate 3 or 5 amp fuse that protects the engine ecu. Worth a look. Not too sure how you managed to connect the battery the wrong way,as the terminals are different sizes?

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Sat 17 Nov 2018 14:23
Mk4 ford mondeo - Mk4 mondeo battery connection fail - S40 Man

Yes the terminal was too small so I just sat it on the top and connected the positive least to negative which was too big. I have dash message now saying immobilizer active. Maybe that is progress.

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Sat 17 Nov 2018 23:54
Mk4 ford mondeo - Mk4 mondeo battery connection fail - S40 Man

OK some slight progress, I disconnected the battery for a while and now I actually get immobilizer activated message on dash display. Have left battery disconnected overnight.

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Sun 18 Nov 2018 09:18
Mk4 ford mondeo - Mk4 mondeo battery connection fail - elekie&a/c doctor

Next step; have you checked fuses in the engine bay fusebox and do the electric windows work?

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