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Matt, Mechanical Engineer
Category: Ford
Satisfied Customers: 22727
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have just driven my Mondeo from the front to the back of

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I have just driven my Mondeo from the front to the back of the house. Left it for about 20 mins while loading the boot (car unlocked). When I got back in the driving seat there were no dashboard lights at all. Car will not respond to power on button when either key is in the car. Have tried a new battery in the key.


I'd next check that the main battery cables are on tight and the terminals are clean and bright. Do the same for the engine / gearbox earth strap.
Then follow the main positive lead back to the engine and down to the starter motor, and check the connection at this end as well.

There should also be a small wire to the motor which should have 12V when you're turning the ignition switch to crank. If the 12V isn't there, check back along this wire for damage to the insulation or corroded connections

This 12V feed comes directly from the ignition switch so this may be faulty and need replacing

Check the resistance of the main positive lead that runs down to the motor as anything more than a few ohms and it should be replaced

Don't forget to try a jump start from another car / battery as its possible the battery is poor, if you have a voltmeter a healthy battery should read 12.7+V

also try substituting the battery for another as I've known a very flat battery to drag down the system voltage too far even with jump cables

one other thing to consider is that the immobiliser is faulty and preventing the starter from being enabled - however if the dash / ignition lights are on then this usually means that its off

Customer: replied 1 year ago.
Really don't think this is it - the car started perfectly and immediately at the front of the house 20 minutes previously. It is not an old battery and the car was fully serviced six weeks ago. There are not lights on the dash - there are no internal lights at all, not even the immobilizer. Everything is "dead" and the central locking will not respond to the key.
Customer: replied 1 year ago.
Have just checked everything above - all is fine



in that case lets try a full reset

by disconnecting the battery cables and clamping them together for 10 mins. Remove both battery leads from the battery then use a nut and bolt or G-clamp to hold both battery lead terminals together.

This discharges any capacitors / memory within the ECU and around the car so ensures all memory settings are wiped clear - back to the factory default.

This will reset all the systems on the car and you may need the radio security code to get it going again, and ensure that the keys are in your hand when you re-connect the battery as the car may lock and turn on the alarm

Customer: replied 1 year ago.
Not keen to do this - I think this is going to a level beyond my expertise with vehicles. Will get a mechanic out to the car.


if you have a voltmeter then you could measure the voltage present at the ECU fuse with the ignition on

as if you have no power to it then its an security issue

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