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Car Wouldn't Start - Odd Circumstances


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Last night I took a friend to a restaurant, but did not lock the car as the outside table we were sat at was facing the car. No tail lights or other lights were visible.

After we had finished, a couple of hours later I got into my 2010 Focus saloon, keyless, automatic, but on depressing the clutch and pressing the start button nothing happened, it appeared the car was dead, and no lights were on the dash or anywhere else. The key fob would not lock the car, so I had to use the detachable key to lock the car. I then got a taxi home.

Today, I went back to the car with a friend and a huge set of jump leads, cabled up, started his car, and noticed that the windscreen wipers wiped then parked themselves.  l Iet the friend's car run for a few minutes, then tried the button on the Focus to start the car, but nothing. Repositioned the cables, tried again and this time the dash lights came on, but flashing, and the electric side window could be lowered (so we could shout to each other), but still nothing when the start Button was pressed, and the lights on the dash went back out.

So I called Roadside Assistance (this is in Spain by the way). The chap came out, brought his power pack with him, hooked it up, took my key and tried to open the doors using the unlock button on the fob. Nothing. Then lock, unlock twice more, and on the third unlock I could hear the door unlock mechanisms kick in and the door unlocked. This time pressing the Start Button worked! After 1 minute he switched off. He tried to start the car, and it started no problem. He suspects the battery, I am not so sure (I have read in other forums strange things about the immobiliser system), but I managed to drive the car home, about 2 miles, and have left the engine running for 30 mins, and have now stopped the car and have left it parked in my garage.

All the cables to the battery were solid and the battery was firmly secured.

Does anyone have any theories about this problem? Battery? Immobiliser? Fob? Something else??


I also noticed that when I unlocked the doors with the detachable key they all unlocked OK, and would lock OK. However, when I unlocked the doors the boot door stayed locked. Does anyone know how to unlock a boot (for example if the battery in the fob dies)?

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My mk2.5 died a couple months ago. Failed alternator and dead battery, AA man couldn’t get mine to start with his van connected to mine either (only managed to get enough in it to pop the tailgate). Sometimes batteries fail big time. 

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  • 2 weeks later...

The ford focus went in for its service today, and I told the mechanic about the problem I outlined in my original post above. He said he had never come such a problem, but he agreed with the Roadside Assistance mechanic who believed it was a battery problem, and recommended that I change the battery in addition to the service. So I told him to go ahead.

I went back after a few hours to collect the car. They had done a full service, changed the battery for a brand new one, and replaced the fob battery too.

When I approached the car in the Ford customer car park, I noticed that the fob unlock had no effect, nor lock.

I informed the mechanic, he also could not get the fob to work, so opened the car with the manual key. He then started the car, and suggested it may have some 'bad stuff' in the car computer memory! He switched off the car, and then tried the fob again and this time it would lock and unlock the car. It said 'that seems to have cleared everything'. He walked back to the maintenance bay and I then got in the car. It refused to start!! So I locked the car, then unlocked it (with me inside) and tried the start button again, and this time the car started!! As I drove past the maintenance bay the mechanic and service manager were coming out. I told them what just had occurred. They asked me for the key then asked me to switch off the car and start it again. I switched off, but again it refused to start. At this point they noticed something on the instrument panel (I couldn't see what). The service manager got in beside me, asked me to try again, and again nothing, he then held the fob against the steering column (where the old ignition key used to go, before they introduced keyless start), and tried again, this time it started.

Ah-ah!! He said, I think I know what it may be. But we will have to have it in for a couple of days to investigate. He explained that a large antenna was built into the car to detect the presence of the fob. It appeared to him that this antenna, or its connector, could be malfunctioning. It said this would explain why the car sometimes appeared to be dead, simply because it was not detecting the presence of a fob key! (They didn't offer me a refund for the new battery I had to buy,  €142 fitted).

So, it is going in again next week for a fuller investigation, and in the meantime they suggested if it started to misbehave again, to gain entry via the manual key, then hold the fob against the steering column to get it started.

Will keep you updated.

PS The mechanic also confirmed that when there is a dead battery problem on the keyless start Ford Focus, you can open all the doors via the manual key inside the fob, but there is no way to open the boot. He could not find a way in via the back passenger seats when they were folded down either.

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on non keyless cars and bikes for the last 20 years the ignition barrels have a receiver antenna that looks for the ignition key's transponder chip, without recognising the key as legit the immobiliser won't let the car start, but because everything else is via a mechanical switch (using the key) everything else continues to work as you expect

on keyless cars, the fob puts out a much more powerful signal (which is why the batteries in the key don't last long) and the vehicle may have multiple antennas looking for the key (boot, each door,  interior etc.), of course on keyless, its not just for physically starting the car, but effectively every feature.... the antenna's can fail as do the other ones on the ignition switch (very common on honda motorbikes)

I did wonder if its because you stayed in range whilst eating that the car got muddled and or a flat battery, but more likely a failure of a component.  

If the battery was more than 4 years old prob worth keeping the new one



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Looking at the Ford Focus Schematics (attached, Sheet 103) it would appear that the Keyless Start system employs several antennas to receive the signal from the fob, which it then passes to a Remote RF Receiver, which in turn sends the signals to the Keyless Vehicle Module, which looks to see if the correct code is encoded on the carrier frequency from the fob, and if it is OK then sends a signal to the ignition system.

As the fob (which has a new battery) does not work anywhere outside of the car, (and I can't believe all the antennas have failed at once) then my suspicion falls on the Remote RF Receiver (12v fed via a fuse), as holding the fob to the steering column has just enough signal power to activate the Keyless Vehicle Module (bypassing the antennas and the Remote RF Receiver). Doing this always gives me ignition when the Start Button is pressed.

Do any of the Ford Focus gurus concur with this analysis?



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