Mk2 Remote locking problem. Key fob appears to be working

[AntonovAN12]

My Mk2 has developed a problem with the remote locking over the last few days.

The fob would sometimes work fine, but other times I would have to press the button a few times to get it to lock or unlock. I have the non flip type key with the three round buttons (Unlock, Lock and Open boot).

It has got worse lately, and yesterday evening it gave up completely.

I replaced the battery with one fresh out of packet, which didn't help at all. I tested the new battery with a multimeter and it was producing 3.1v compared to 2.8v from the old one.

I tried the programming sequence in the owners manual. This says that the key can be matched by pressing any button. I tried it three times, each time pressing a different one of the three buttons.

Each time the button was pressed, the car responded with a beep. This suggests that the remote buttons are working and it is communicating with the car.

However none of the buttons work their normal function when pressed.

I have checked for water in the passenger foot well fuse box, and there are no signs of water or corrosion. I also removed, checked and reseated fuse 55 and 77. Both were intact.

Is there anything else I should try?

Thanks for any advice.

[StephenFord]

Interesting that you've had no replies to this so far, and I'm guessing it's because you already have done all the basic diagnostic steps, including confirming the 3.1v battery output (more than enough), which would often be the most common cause of a fault.

I fear that I personally can suggest nothing further (sorry...) but hopefully one of the more intelligent members of this community will drop in soon.

[DaveT70]

Can be a couple of things,

Best case is the battery you put in wasn't very good, you may be getting 3.1v put could still be poor. Was it a cheap chinese/poundland jobby?  Try a genuine Panasonic or Energizer battery first.

It could be the buttons in the remote are going down, but that's usually just one, not all three at the same time so I'd rule that out. You could try programming a known working second remote to see if it starts working.

On early MK2s the RFA (Remote) sensor is mounted above the interior rear view mirror, under the courtesy lamp and has a strap that comes off it and mounts to the body. Water leaks from the aerial can cause rust on the connection to the body. Remove the sensor, remove the earth strap bolt, clean the area and grease and re-fit. 

Now, the bad part, 

When the BCM (it may be called GEM on your car) is going down, the first system that packs up is RFA (Remote sensors).

Remove the BCM from under the glovebox (disconnect battery earth first) remove all the connectors and see if you can see green fur on the connector pins on the circuit board. If you can then the BCM is going down and you'll have to source a good replacement.

[StephenFord]

See, I told you one of the more intelligent members would be along soon!

[AntonovAN12]

Thanks for the replies.

I did fit a cheap battery, but if the car responded when I pressed the buttons, surely the signal is being received? I will try a better quality one first. For now I can still unlock, lock and start the car with the key.

I got one remote key and one non-remote spare key with the car. I did think of trying another remote. Are the remotes from the Mk1 Focus compatible? Apart from the shape of the metal key itself, the Mk1 remote unit looks the same.

I removed the courtesy lamp cover earlier today. There is no sign of any corrosion to the connections behind it. Everything looks clean and shiny. What does the sensor look like? From the quick look I had, I couldn't see anything in there that looked like it could be it.

By GEM unit do you mean what is commonly called the fuse box? By "going bad" do you mean damaged by corrosion from water? Am I correct that a replacement used unit needs to be programmed to the car when fitted?

[unofix]

GEM = General Electric Module - later replaced by BCM = Body Control Module.

On most Ford vehicles they are part of the Fusebox in the passenger compartment. To put it simply they are a mini computer that handle things like: Low beam Headlight, Indicators, Wipers, Screen Wash, Alarm/Security.

The GEM/BCM is a circuit board on the back of the Fusebox and on a number of models is prone to corrosion due to water from the screen wash pump.

[DaveT70]

11 hours ago, AntonovAN12 said:

I did fit a cheap battery, but if the car responded when I pressed the buttons, surely the signal is being received? I will try a better quality one first. For now I can still unlock, lock and start the car with the key.

 

put a better battery in first

 

11 hours ago, AntonovAN12 said:

Are the remotes from the Mk1 Focus compatible? Apart from the shape of the metal key itself, the Mk1 remote unit looks the same.

Stick to the same style/look/period

 

11 hours ago, AntonovAN12 said:

I removed the courtesy lamp cover earlier today. There is no sign of any corrosion to the connections behind it. Everything looks clean and shiny. What does the sensor look like? From the quick look I had, I couldn't see anything in there that looked like it could be it.

On the roof panel, like a ribbon lead with a bolt into the body. It was not on some models though so may not be there

 

11 hours ago, AntonovAN12 said:

By GEM unit do you mean what is commonly called the fuse box? By "going bad" do you mean damaged by corrosion from water? Am I correct that a replacement used unit needs to be programmed to the car when fitted?

AS Unofix said, but washer hose was MK3, the MK2 GEMs were killed by poor fitting pollen filters leaking from the HVAC. Yes, replacement GEM has to be programmed to your vehicle

[Dan62]

Check the gold contacts on the keys PCB where the chrome battery contacts touch when the key is assembled.
The gold tarnishes giving poor electrical contact. Lightly clean with something mildly abrasive like a fibreglass pencil.
 

[mjt]

11 minutes ago, Dan62 said:

The gold tarnishes giving poor electrical contact. Lightly clean with something mildly abrasive like a fibreglass pencil.

Gold does not tarnish. It is one element that does not react with oxygen. The contacts may become dirty if batteries have been inserted that were contaminated (e.g. with skin oil). It's best not to use any kind of abrasive on the gold as the plating is very thin and could easily be worn through. It should only need cleaning with a dry cloth or, if contaminated, with something like Iso Propyl Alcohol.

[Dan62]

7 minutes ago, mjt said:

Gold does not tarnish. It is one element that does not react with oxygen. The contacts may become dirty if batteries have been inserted that were contaminated (e.g. with skin oil). It's best not to use any kind of abrasive on the gold as the plating is very thin and could easily be worn through. It should only need cleaning with a dry cloth or, if contaminated, with something like Iso Propyl Alcohol.

Poor quality industrial gold does, not helped by having non gold to gold contacts which cause galvanic corrosion.
The contacts are on the PCB not the battery side of the fob so unrelated to inserting contaminated batteries.
The key doesn't work, you can get a few more years out of it possibly by cleaning the contacts or adjusting the contact points.

[AntonovAN12]

Thanks for the replies. I can hopefully pick up a better battery tomorrow.

4 hours ago, DaveT70 said:

On the roof panel, like a ribbon lead with a bolt into the body. It was not on some models though so may not be there

The parts diagrams show a unit called a "Receiver - Radio Remote Control" that is supposedly behind the radio.

I can't be certain that there isn't another sensor, perhaps I didn't manage to find the correct diagram.

https://ford.7zap.com/en/car/43/6.1682,7.29708,12.39889,15.9644/0/1659/16058/70121/#15K602

[DaveT70]

2 minutes ago, AntonovAN12 said:

Thanks for the replies. I can hopefully pick up a better battery tomorrow.

The parts diagrams show a unit called a "Receiver - Radio Remote Control" that is supposedly behind the radio.

I can't be certain that there isn't another sensor, perhaps I didn't manage to find the correct diagram.

https://ford.7zap.com/en/car/43/6.1682,7.29708,12.39889,15.9644/0/1659/16058/70121/#15K602

It should be up in the headliner

[AntonovAN12]

I fitted a better battery earlier today and tried the key programming with exactly the same result. That is that the key appears to be transmitting to the car, but still not actually working the locking functions.

It seems like the signal is not getting from the GEM to the door locks. Other than a water damaged GEM, could a loose or broken wire somewhere be a possibility?

I had another look above the courtesy lamp and think I can feel the wire leading away to the sensor. I don't want to pull it too hard to avoid damaging it.

I have also read that temporarily disconnecting the car battery earth lead has been known to solve the problem, so will try that next. I also still have to try disconnecting the GEM leads, but need to use the car over the weekend so haven't yet had time for that.

Failing that, the small independent MOT centre I have been using for years have recommended a mobile auto electrician. Would connecting a diagnostic unit give any more clues?

[Tdci-Peter]

14 hours ago, AntonovAN12 said:

It seems like the signal is not getting from the GEM to the door locks.

Have you tried activating central locking in other ways, using the key in the driver's door, or the internal locking button on the driver's door? They all use the same motors and control signals from the GEM/BCM.

From the Focus circuit diagrams available on this site, and from what I have seen, the RF locking receiver should be above the headlining near the front of the roof.

Also do the door ajar signals all work ok (including boot), lighting the warning light & dome light when expected? These signals can prevent the central locking from working.

For the Focus schematics, see:

 

[DaveT70]

2 minutes ago, Tdci-Peter said:

Also do the door ajar signals all work ok (including boot), lighting the warning light & dome light when expected? These signals can prevent the central locking from working.

That is a very good point

[AntonovAN12]

7 hours ago, Tdci-Peter said:

Have you tried activating central locking in other ways, using the key in the driver's door, or the internal locking button on the driver's door? They all use the same motors and control signals from the GEM/BCM.

From the Focus circuit diagrams available on this site, and from what I have seen, the RF locking receiver should be above the headlining near the front of the roof.

Also do the door ajar signals all work ok (including boot), lighting the warning light & dome light when expected? These signals can prevent the central locking from working.

Thanks for the reply.

Both the driver's door key lock and the internal locking button lock all doors as normal.

I am certain I can hear the locking receiver moving above the passenger side sun visor when I move the wire.

All the door ajar signals are working as normal.

Earlier today I went into a place that repaired a central locking problem on another car I had back in 2010. They have a device to test the remote fob, and say it is working perfectly.

 

 

 

[Tdci-Peter]

4 hours ago, AntonovAN12 said:

I am certain I can hear the locking receiver moving above the passenger side sun visor when I move the wire.

You seem to be doing quite a good job of narrowing it down to the CL receiver! - or its wiring & connections.

It goes to pins 6 & 10 of C98 in the BCM:

 

This is the smallish plug at top left of the unit. At the receiver there are 3 connections:

Pin 2, Black, is a local ground to the roof.

Pin1 (Orange-Yellow) is 12v from the battery (permanent on, via fuse F102 in new boxes or F43 in old boxes)

Pin 3 (White) is the data signal, probably 0-5v serial data.

I managed to lower the front of the rooflining in my estate once, it is not difficult, just fiddly & time consuming. It is held up by all the fittings screwed & clipped through it, and needs quite a lot of the trim panels on pillars & over doors to be unclipped. Haynes did help a bit with that!

However the fact that the car beeps when in programming mode does suggest the receiver is working. I am sure it is just a simple RF to serial data converter, all the security coding etc is handled in the BCM. So the BCM can, it seems, get signals from the fob, and can lock/unlock doors when it wants to, but can't put these two together! That is a bit of a mystery that I don't like, and can't think of a likely cause or answer, apart from some sort of software corruption or fault.

 

[AntonovAN12]

I will try the car battery earth disconnect / reconnect this week. I saw this mentioned in an old post on another forum that I can't find again.

I don't hold much hope of it working, but it is easy enough (and free) to try.

This problem made me wonder if anyone has tried fitting a boot opening switch on the Mk2 dashboard. Apparently the Mk1 Focus did have one as well a key lock in the boot lid.

It's a good thing the remote locking problem didn't happen before I fitted the replacement boot switch. If it had, I would have been left unable to get into the boot without removing the latch bolts.

[mjt]

13 hours ago, AntonovAN12 said:

Apparently the Mk1 Focus did have one as well a key lock in the boot lid

It did, and removing the option of a direct mechanical link to the boot latch was a big mistake IMHO.

[AntonovAN12]

UPDATE - PROBLEM SOLVED.

Disconnecting the car battery for a few minutes actually worked. Remote locking now functioning as normal.

Thanks everyone for the suggestions.

[StephenFord]

54 minutes ago, AntonovAN12 said:

UPDATE - PROBLEM SOLVED.

Disconnecting the car battery for a few minutes actually worked. Remote locking now functioning as normal.

Thanks everyone for the suggestions.

Who knew!! Always thought that was like the standard IT advice of switching off/on your computer LOL 🤣

[mjt]

AFAIK that only applies to Micro$oft Windows. Other OS's are written properly.