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Mondeo Alarm and Central (including remote) Locking Problems

All UK made Mondeo's have central locking, an alarm, immobiliser and double locking as standard. Optional equipment included remote central locking, interior scanning and glass breakage sensors (Estate only). There are a number of problems you can encounter with the earlier Mondeo's alarm system. Most involve one or more parts of the system failing. The LED next to the clock should light up for 5 seconds with the ignition, if it remains lit for longer then this period then the alarm system is reporting an error.

There are 3 parts to the alarm system. The central locking, the alarm system and the double locking.  Central locking should activate when either of the front doors are locked from the inside, from the outside with a key or by pressing the lock button on the remote control once. If the car is locked from outside (with key or remote) then the alarm should also be set but there will be no noticeable confirmation other then to look into the car at the red LED next to the clock which should flash rapidly for 20seconds before becoming more steady. Double locking will occur when the car is unlocked and then locked (within 3 seconds) by either front door or the lock button on the remote is pressed twice in quick succession. When the double locking is activated (depending on year) you should get either 4 beeps from the car or 2 indicator flashes (Assuming you have fitted the double locking/alarm active relays - See How-To) and you should hear the double locking motors working. If you have interior scanning (Ultrasonics) then these will also be activated with the double locking. If your system isn't working like that then you have a fault and so read on:

Some Common Mistakes:

  • The interior scanning is only activated when the double locking is activated
  • There is no notification (beep or flash) that the alarm has been set, only when double locking is set.
  • The alarm will only flash the indicators if the relays have been installed and the module supports it (Mk1 only)

First carry out the alarm test, details can be found here > -Test- so you can begin to narrow down the fault! Don't worry if your car won't go into test mode, it may still be correctable!

The first thing to do is locate the alarm module and the various parts that make up the system. If you look under the steering wheel, just to the right of the accelerator pedal you'll find the alarm module. Its labeled "B" in the image below and you may have a large silver box in front of it.


Before we start, the very early mondeo's (1993 & 1994) had a problem with the alarm's connectors becoming loose so the first thing to do is take each one out in turn, spray it lightly with WD40 and then replace. Remove and replace the connector a couple more times to aid connectivity and then move onto the next - There are three in total.

The following diagram shows you the rest of the alarm systems components and the respective locations.

1 - Control module, the alarm flasher relays and the diagnostic interface multi-plug.
2 - Sensor remote control (where fitted)
3 - Key-activated door lock switch
4 - Door ajar switch
5 - Interior scanner (where fitted) - Top of B pillar
6 - Luggage compartment anti-theft alarm inhibit switch
7 - Tailgate/luggage compartment lid ajar switch
8 - Luggage compartment lock isolator motor
9 - Alarm system horn
10 - Central timer (fitted on underside of fuse box)
11 - Indicator LED
12 - Alarm system buzzer
13 - Hood ajar switch

No central locking / alarm / double locking:

This will more then likely be caused by one of three things. 1) The power connector has fallen out / become corroded from the alarm system - check the last connector on the far right of the module. 2) The fuse for the system has blown - in the passenger footwell fuse box, test and replace fuse number 25 - Its a yellow 20amp one and supplies power to the control box. (Also check fuses 30 and 32 whilst there)  3) The alarm module box has failed in some way. Replacements are expensive from ford so go to your local breakers and try one from there. All mondeo's of your year (except diesel's and ST's) will have the same alarm module as yours so you can take it from an aspen or a Ghia - it makes no difference. The alarm module changed wiring connectors from 95 onwards so you'll need to find the module that suits your car and make sure you test before buying!

Failure of one or two parts of the system:

This will normally be the alarm and double locking that fails leaving just the central locking. Its caused by a dodgy join in the drivers footwell. You'll need to put the seat in its furthest back position and remove some trim to gain access. Lift the carpet and insulation foam up from the door side and you'll discover a mass of cabling:

Now you'll find it comes down from the drivers side kick plate, disappears into plastic tubing for about 20cm (whist it rounds a corner and drops down) and then is a free loom again for another 20cm or so before disappearing into some more tubing going under the seat. Its this tubing that you'll need to cut back in order to expose the join (one side of the tubing is made of tape so cut that but VERY carefully to avoid slicing through your loom!!!)  About 5cm in you'll find three small orange cables from the rear of the car joining one larger one from the front of the car. This is done under some black insulating tape and its this join that is susceptible to corrosion. Remove the tape and inspect the joint, if its clear then re-tape but more commonly then not it'll be a greeny/blue colour and will need to be re-soldered. You may also find some heat damage to the cabling leading into the joint in which case you'll need to splice in some new cable. There is also a thin white cable with a red line running in this part of the loom (which feeds the tailgates double locking motor) that can become heat damaged so look for signs of damage to it.

Now if all the wiring and the joint appears to be in good condition then the next big cause is the bonnet switch, especially if both your alarm and double locking have failed at the same time. In order for the alarm to set it requires that all 6 (bonnet and boot) doors are fully closed. If any of them are ajar then the alarm won't set and the double locking will not operate. The bonnet switch is the most likely of all to fail as its not encased in metal and exposed in the engine bay. A replacement part is about £12 from ford. There is no real way to check if the bonnet switch is faulty other then to fully examine it, it found on the front cross member of the bonnet on the left side (looking from front). It should have a rubber boot that covers the plunger and if this is no longer in-tact then chances are water will have gotten down into the switch and its either stopped working completely or is intermittently working (Especially if your alarm is occasionally going off for no reason - see "If your alarm is going off for no reason without double locking set" later)

If the bonnet switch is OK then it could be caused by a faulty door switch, remember that these things are engaged and disengaged every time you open a door and so will break down over time. There is one in each door and the wiring is linked directly back to the alarm module. If the system will go into test mode then it should be easy to identify which door is causing the problem. Open them all in turn and the alarm system should beep. If any of the doors to not beep then that switch has failed (Continue the test in case another has also failed). To get to the switch you'll need to remove the door-card and then take out the locking module. (Disconnect the external door handle then undo the three bolts and single screw on the side of the door. You can now work with the module enough to be able to undo the plastic cover and look at the switch.

The above picture shows a new switch ready to fit, note the wiring connectors. The picture below shows a close up of what happens to them after time: (Thanks to L-Plate from MEG for these pictures)

Central locking and alarm working but no double locking:

This is normally caused by a faulty double locking switch in either of the front doors. Again 93/94 cars were most effected with the switches gunging up and sticking in both on and off positions causing an error code and the double locking system to stop responding. The switches are located on the lock barrel itself and can be a bit fiddly to get to. You need to remove the door cards and then the foam panel. From there you can look in and remove the two bolts holding the outside handle to the car, then remove the three bolts on the side of the door and finally the small screw to the above right. Now you can withdraw the entire lock system out from the door and inspect the switch. If they are faulty you can get new ones from Ford, the finis codes you need are - Left 6-950-444 and Right 6-950-445.

If your alarm is going off for no reason without double locking set:

If this is the case then the problem will normally be the bonnet switch as its exposed to the elements 24/7. There are two common faults with it - the biggest being the rubber boot that covers it has worn allowing moisture to enter the switch and cause false readings (See "Failure of one of two parts of the system") The other is that the bonnet isn't closing tightly on the switch. This can be rectified by adjusting the bonnets rubber seating bung (one either side of the front cross member) until the bonnet sits tightly on the switch.

If your alarm is going off for no reason with double locking set:

This can be due to a couple of things. The biggest cause of false triggers is with the interior scanning system which activates automatically when you double lock the car. Ensure that when you set it every window is done up tightly, including the sunroof and boot as air moving in the interior will trigger the alarm! Other reasons will be damaged door/sunroof seals allowing drafts or connector problems.

Here is the interior scanner with the cover removed from the B pillar (the one's by the front seats) You can see the wiring coming down from the roof (the yellow looking wires with the black tape around them) which goes down and into a connector on the bottom of the scanner. Unplug and check nothings corroded and then reconnect. Whist here check there is no spider web over the front of the scanners (the silver circles either side of the unit) as this can also trigger false alarms.

If your alarm module is not allowing new remote key programming:

Effecting a large number of control modules, although mainly Mk2 - the module collects static electricity down the aerial wire. Over time this stops the system from recognising the existing code from the IR keyfob leading the owner to attempt reprogramming (which is also not possible with static on the aerial). There is no real solution for this problem although a temporary fix can be done - unplug all three (in some cases just two) connectors going into the alarm/control module, leave for between 10 and 15 minutes to allow the static to dissapate. Reconnect and reprogram the remote (Details) . The immobiliser system stores its code on memory known as ROM which is unnafected by power loss and therefore will be unnafected and should NOT need to be reprogrammed.

This fix will last for an undertemined period of time - normally it recurs after a couple of months, although this can be extented by following the instructions for extending range below

Extending the range of the Mk2 remote central locking:

Mk1 and early Mk2 cars use IR central locking which can't be extended, however later type RF locking (see key types to determine which one yours is) can be in some cases. You should be able to lock / unlock the car from a good range - about 100 yrds. If your car suffers from poor range then this could be due to the aerial cable being curled. Fnid the alarm module and check the two connectors coming from it - on one should be a solid orange cable - this is the aerial and you'll see it dosn't terminate anywhere. It should be strait and uncurled although often when the car was assembled the cable was wrapped up causing signal loss. Straitening this cable and attaching the end to the highest possible point should dramatically increase the range, when straitening the cable try to keep it from touching anything - the sound proofing especially. This reduces the amount of static electricicy that can be transmitted to the aerial cable.



Copyright Mirez - 17-APR-2003 - All Rights Reserved.

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