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Discussion Starter #1
I see a few questions about keyless entry problems, but no answers..

to unlock the car doors, now I have to hold the fob right by the drivers window, whereas I used to have 30 feet or so range.

I think the problem might have started when I replaced the alternator, and had to disconnect the battery. I double checked the connections, and they are OK

My questions are
1) Anyone else had the problem, and if so what was the cure

2) I suspect the leyless entry module (body control module under the glove compartment.
Can I just buy a new module and install it, there are plenty available on Ebay.. or does it have to be programmed by a dealer.

3) What is the ballpark cost for a dealer to fix it ?

Thanks for any insights

M
 

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Have you ever replaced the Fob battery?

Range goes down as the battery gets old....
 

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Just for the sake of supposition, what if all 3 were low.
 

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Hear the repeat, but no new info.

Just don't see your assumed problem here (needs new BCM), that's why the 'silly" sounding question on the fobs/batteries. That's a known & common cause of the symptoms described.

Digital VOM readings on the batteries?
 

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Hear the repeat, but no new info.

Just don't see your assumed problem here (needs new BCM), that's why the 'silly" sounding question on the fobs/batteries. That's a known & common cause of the symptoms described.

Digital VOM readings on the batteries?

I had the same problem I had two fobs for my focus. Very short range,
Checked the batteries with an analog volt meter and they read fine. I borrowed a friends digital one and they were both about a volt low. Replaced them both and it worked about a forty foot range give or take a little depending on weather and what was next to my car
 

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Discussion Starter #8
Just to be 100 % sure I just checked all the batteries with both an analog meter and a digital, and they both read full 3 volts.
Then I bought a brand new battery, and installed in one of the fobs.
Still the same problem.
 

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Are you possibly near another radio source that's confusing the car till your fobs are the strongest signal. Petrol station? Ham radio? Airport radar? Etc
 

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That makes sense. I monitor cb radio occasionally and I was playing with my keys. On certain stations I can hear an audible tone when I press the trunk button
 

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Discussion Starter #12
Its not another radio source, as I have tried it at home, at work, and way out in the country. The problem is almost certainly the receiver or Body Control module, I guess I'll just have to buy one and see what happens. Since it still works somewhat, Im reluctant to take it apart.

I have heard that occasionally disconnecting the battery, as I did when replacing the alternator, can cause problems like this.
 

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On the Mk3 I have their are 3 receivers. If that's the case for your earlier car would suggest the controller rather than all 3 receivers at the same time

Have you tried putting the remote to your chin when you press the button, sounds silly but by using your head to extend the aerial you double the range. Been tested and works

Also try it without your phone on you

Have you moved something metallic in the car like a tyre pump, try moving stuff around
 

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Discussion Starter #14
Problems That May Occur If You Disconnect Your Car battery

What happens when the battery is disconnected? It depends on the year, make and model of your vehicle, but any of the following may happen:

It erases all the learned values in the PCM's Keep Alive adaptive memory. This may cause the engine to run poorly because the air/fuel mixture is too rich or too lean for a period of time until the PCM can relearn the fuel trim adjustments. This may take up to several days and 50 to 100 miles of driving until engine operation returns to "normal."

Erasing the PCM's adaptive memory may also affect the way the transmission shifts and feels. The transmission may not feel the same until the PCM or transmission control module relearns the shift adjustments. This may take 50 to 75 miles of driving.

It resets the FMEM (Failure Mode Effects Management) module on certain late model Ford vehicles. This module provides an adaptive fail-safe strategy that substitutes estimated or fixed data for missing sensor data. Normally, this should not cause a problem UNLESS the vehicle has a bad sensor and has been substituting data from the FMEM module for a missing input.

It resets the ABS (Antilock Brake System) and SIR (Supplemental Inflation Restraint) or airbag modules. This should not be a problem UNLESS one of these modules requires a special relearn or reprogramming procedure after power has been lost. In that case, the affected module may prevent the ABS or airbag systems from working.

It resets the Climate Control module. On some vehicles, the module will not start working again until a special relearn procedure or reprogram procedure is performed with a factory scan tool. That means no A/C until the module is programmed with the correct instructions.

It resets the Body Control Module (BCM). Like the Climate Control module, the BCM may not resume normal operation until it has undergone a special relearn procedure or is reprogrammed with a factory scan tool. This can mess up the operation of power accessories such as power windows, memory seats, power sunroof, or electronic suspension settings. Worse yet, the BCM is the "gate keeper" module on many 2003 and newer vehicles that have a CAN (Controller Area Network) system. If the BCM cannot communicate properly with all of the other modules, or it does not recognize the addresses of other modules, it can cause all kinds of problems.

It may reset or disable the anti-theft system. The engine may crank but not start because the anti-theft system thinks somebody is trying to steal the vehicle. Again, it may require a special relearn procedure or reprogramming the anti-theft system with a factory scan tool to resolve the problem.

It causes a loss of channel settings on an electronic radio and clock. This is more of an annoyance than a problem, and can be fixed by resetting the radio channels and the time.
 

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The range on my '01 was never great, but I had the same problem. Some days would lock fine, but not unlock. Other days would be the opposite.

Turned out the switches in the fobs had gone bad. New fobs worked like a charm.
 

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Problems That May Occur If You Disconnect Your Car battery...
Wow, the whole post has a lot to chew on.

It resets the Body Control Module (BCM). Like the Climate Control module, the BCM may not resume normal operation until it has undergone a special relearn procedure or is reprogrammed with a factory scan tool. This can mess up the operation of power accessories such as power windows, memory seats, power sunroof, or electronic suspension settings. Worse yet, the BCM is the "gate keeper" module on many 2003 and newer vehicles that have a CAN (Controller Area Network) system. If the BCM cannot communicate properly with all of the other modules, or it does not recognize the addresses of other modules, it can cause all kinds of problems.
BTW, I have a 2004 with CAN-bus and my car does not have a BCM. On my car, CAN-bus goes to/from the PCM, Instrument Cluster and OBDII port. What year did <most> the Foci start using the BCM?


It causes a loss of channel settings on an electronic radio and clock. This is more of an annoyance than a problem, and can be fixed by resetting the radio channels and the time.
With battery disconnected, my stock radio holds presets (for a very long time) and only loses the presets when the radio control head is disconnected. I think I once lost my presets after having the battery disconnected for more than 24 hours.
 
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