Body Control Modual

[ged65]

Hello, I wonder if anyone could advise me, I know a middle aged lady who is disabled with Crohn's disease and has a Ford Fiesta Zetec 1.4 Mk7 petrol. She needs this to be able to have any sort of life, hospital visits etc. Recently her car lost all power, we thought it was the alternator, but it appears that it is the Body Control Modual. I understand that to purchase a replacement and have it fitted and set up can be very expensive, anywhere between £500 and £1000. The other problem is that try as I might I cannot locate anyone in the Doncaster area of South Yorkshire in the UK who can replace this for her apart from a main dealer who she cannot afford. I wondered if anyone on this forum might be able to advise?

 

[scotman]

I would first determine whether the BCM is actually defective or perhaps it just has a ground connection that needs to be cleaned. You don't mention the model year, so my response is going to be rather generic.
I would first determine the condition of the ground connection (or negative earth) of the BCM.
If that is confirmed to be good and module is bad. Another one could be sourced through a wrecking yard. You would need to have the Vehicle identification number and possibly the build date for the Fiesta. Both of those can be found on the drivers side B pillar. Down near the rocker panel. Once you have that information and the determined defective module engineering part number ( which is on the module itself) you can then accurately find a replacement.
This forum is aimed primarily at the North American version of the Fiesta. So, i can't specifically address the 1.4 Fiesta. In America i am seeing used BCM for fiesta being offered for less than $100 usd.
Having a shop that has an experienced technician diagnose this issue is the best way forward. It may save money and time.
Unless a qualified mechanic has checked out the grounds, i would be very suspicious of off the cuff or sight unseen guessing!
Good luck with this and please post up an update on the outcome.

 

[Handy Andy]

To add:

The BCM also has a Ignition Defeat system in it. It's designed to disable the vehicle when someone tries to jimmy the lock and attempt to steal the car.

IF one or both of the keys for it have dead batteries, this interlock engages and until the batteries in the keys are replaced, this would make the BCM seem "dead" and need replacement.

It may only need to have the keys' batteries replaced and the battery negative (ground) cable pulled and left off for 10 minutes or more - then battery cable power reapplied (attached) and hit one of the keys "unlock" - and see if it unlocks the doors - and see if the vehicle can be started.

 

[ged65]

Hello, Thank you for your replies, which I truly appreciate, I thought I would give a little more detail to see if this helps. For the past couple of years if the car has been left for a couple of weeks the battery will be flat. A replacement battery did not help. The starter motor was replaced and the key barrel after the starter was not engaging properly, this seemed to stop the starting problems, but not the flat battery problem. A test to see if the alternator is charging the battery shows that it is. Another problem has been that after locking the car, the next day, or after a few hours the doors are found to have unlocked themselves. The last journey for the car was to a supermarket four miles away, on the return journey the car started fine, but when she got to the traffic lights near the supermarket she indicated and the indicators were VERY RAPID, though no bulbs are out. Half a mile later the panel lit up with every warning light you can imagine and the windscreen wipers came on and then a total power failure...Are these symptoms indicative of a BCM fault? or is it something else. After charging the battery it all seems to be working fine, surely if the car starts and is running and the alternator is working ok, there should not be a total power failure and a battery that is totally discharged? Is there anyway to diagnose exactly what the fault may be? Would a code reader tell me if the BCM was at fault? The car is a FORD FIESTA 1.4 PETROL ZETEC CLIMATE registered in 2007

 

[scotman]

Is this car operated in a sea air environment? IE; along or near the english coastline?
If so, it is a fourteen year old vehicle. That is not a problem in itself. But, again Ground conditions. With the addition of a moist, sea air environment would work on the wiring harness and increase the resistance in the electrical system anywhere it can get in. The Fiesta seems to have under hood fuse box corrosion issues as it ages.
I would be looking in the under hood fuse box first! Gently remove the relay for the alternator and observe the pins. See any white powdery or pastie looking stuff? The pins should look clean and at least somewhat shiny. As you would expect a conductive surface should be.
It is obvious, given the behavior you just described, that the situation is not one of multiple system failure all at once. It is a multiple system failure due to the lack of stable voltage.
Maybe Andy could shed a more focused light on the root cause.
If I were looking at this car, i would begin cleaning ground connections and checking the fuse box and relays. Given the age of the Fiesta, i would probably be removing the front seats and giving any ground connections that reside there a very thorough inspection.

 

[Handy Andy]

If I were looking at this car, i would begin cleaning ground connections and checking the fuse box and relays. Given the age of the Fiesta, i would probably be removing the front seats and giving any ground connections that reside there a very thorough inspection.

That is where I would go next...

There are two - one on the Drivers side, the other on the passenger side.

Both use a BOLT into the frame cross member that also BOLTS the seats to the floor.

So to find it, you pull the weather-strip on the floor sill, to help you get access to pry up that plastic trim - once you have the trim remove lift up the carpet - it's right there.

Both sides need to be checked and as needed cleaned and reseated, and on my 2018 - is bundle of wires Black Violet/Purple Stripe as the major ones, are SOLDERED into a lug and bolted to the frame.

• now if it were me, I'd get a little propane torch and solder, and reheat, reflow solder and replace the lug back onto the bolt, using a copper based lubricant - ones that work for anti-seize compound and or battery terminals. Worth the investment if you can take the time to DIY ground connections.

​

You don't have to remove any seats or extra trim - just examine and if needed - clean it up from rust and debris - and re-oil-lube/retighten the bolt to seat the connection back to frame.

 

[scotman]

Those under seat grounds will be a growing issue. The odds of windows being left down in rain storms and all the tracked in moisture of normal use, along with the occasional spilled soft drink or partially drunk Gatorade bottle that will get kicked under the seat with a loose cap that will help speed up the corrosion. Not that i have ever seen that sort of thing occur! (Im lying. I have)
It is such a joy to shovel my way through the garbage pile of fast food and spilled drinks under the seats of cars. But, not even finding a dog hair and sesame seed freckled Polaroid picture of the car owners wife with her top pulled up to collect more mardi Gras beads, is a satisfactory reward.

 

[Handy Andy]

In light of the Alternator, I wonder if you have a simple tool that I found - beats any moneymaker YT or any person trying to take advantage of others that are desperate for ideas on fixing their car and finding low-cost methods to avoid getting stuck with big repair bills...

Got a Electrical Tester?

Like this

​

Because it also can be installed from the Battery Positive Terminal - to the Ground Bolt that the Battery Ground cable goes to...

Why? Because you can look for SHORTS, as well as ACTIVE circuits...

Then Why Filament? Like a Flashlight?

Yes. Because there will be times where a LOAD is needed to be placed across the system, to drain the capacitors and extra stored energy when you need to reset the PCM or even the BCM due to a fault that got fixed, but the system needs to drain itself so it can "boot" from it's OEM and "Learn" your new fixed system all over again - a form of training the PCM and BCM to start talking to one anther and learn each others habits. A simple Flashlight bulb of the older Filament.

How is that done?

See the Clip? That clip bites into attaches to the Ground Bolt on the car, you can then place the testers probe lead into the Positive terminal using the Post to terminal clamp "gap" to hold the tip.

Bury it, stick it in - firmly into the gap between the positive post and the bolted clamp and note the light is now on - now disconnect the Battery Negative post clamp and the light will go out - the Filament has taken all the STORED energy thru itself - into Ground as a Short - the Bulb will light when there's plenty of power from the Battery.

But when you pull the Ground cable - the stored energy flows thru the bulb and to ground. The circuit provides a means to drain the systems own power to ground thru this circuit - the tester uses the standard filament bulb to light, but the bulb itself is wire - so it too can act like a dead short. This drains the system - leave it in this state for 10 minutes to ensure the reset is complete. Reconnect the Ground cable to the Battery post, the tester will light up and you can remove the tester from the post and ground bolt - RESET complete.

The Filament is a wire - a piece of metal (Tungsten/Nichrome) that heats up and glows brightly when power flows thru it. A wire can pass any power thru itself - the Filament being metal like wire - can also pass power thru itself. When power flows thru this filament - it starts to heat up because is has a small amount of resistance when the wire is cold - heating causes it to exhibit a resistance to the flow of power and it exhibits an increasing resistance to the flow of power thru it. It is an electrical short - much like a fuse, but controlled, by the type of metal wire used as the filament. It will light - getting brighter until it too passes a point of too much power and the filament opens - just like a fuse.​

​

Otherwise it looks like a dead short for any lower voltage and current - it will still flow thru it, just there's not enough power in the trickle charges left passing thru it to light the bulb but still allows power thru it and looks like a dead short.​

​

This is how you can reset the system and drain off the Non-volatile Memory - forcing a reset. Apply a short across the terminals - using the filament of the bulb of the tester to provide the short - you use the tip to one and the clip to the other terminal you make a circuit complete - it will consume all the power within it. This drop causes the memory to be erased - reset to "0". .When you reconnect the battery to supply power - the memory of previous operations and performance, emissions and control states are lost, emptied, removed - you start over.​

Now you can also use it to determine is power drain is thru a charging system issue or you have an accessory still using - pulling power from the battery - you can do the same test only instead of placing the leads across the battery - you use the Tester as a CONDUCTOR - like the Ground Cable it takes place of it - power losses will light the bulb.

Here's an Example
​

• - to find out if you have a power drain
• Start the car
  • - and verify you have air AC fan stuff like that, then you switch off all lights, overhead, turn off everything
  • - and make sure sure all the doors windows and anything else shut closed
  • - ONLY roll down DRIVERS SIDE Window - leave the car in PARK - pop the hood,
  • Get out of the car - close the door,
  • you left the engine running and at idle
    • - so you have a system charging
    • - open the hood and prepare the tester to act like the Ground cable
    • - you're doing all of this while the engine charges the battery and all the accessories are off
    • - now once you're ready
    • - don't open the doors, just reach in and turn off the ignition - PULL THE KEY - Everything off ok?.
• Go back to the Battery Post Ground cable - loosen it but don't pull yet, allow the engine to POWER Down - reset the fuel injectors and seat the throttle - all the stuff it needs to do to power itself down.
• When it's quiet (the engine) now reach for the Ground Cable and pull it - AT THE SAME TIME - attach the Tester to the Battery Post with it's Clip to ground bolt.
• - you attach the Tester tip to the NEGATIVE POST POST of the Battery - the Circuit Tester completes the Circuit, acting as what the Ground Cable does.
• - The Clip goes to the ground bolt - and tip to Negative terminal - then loosen the Battery Clamp and pull the Ground cable .

Now, the moment of truth - When the Battery Cable is removed from the Post, the TESTER becomes what that Cable did - does the Tester light? Ok if it does, give it a moment - leave it in this state for several minutes.

Does the light stay on? Then your answer is YES, it's some kind of Electrical fault in the system - you DO have a power drain in the system.

Might need to have the Alternator rechecked. It may be a Diode in the Alternator - or a A/C relay not clicking off.
Could be a Dome light switch gone bad, onto a Trunk compartment light stuck on, to a Glove Box courtesy light doing the same thing. The Air damper door cycling all the time - because it can't tell the BCM it's parked.

Even a Fuse that got put in in the wrong spot - now a circuit is active that shouldn't be - draining the battery.

Does this mean the BCM is bad? Maybe. How about the PCM? Possible.

So what steps can be taken? May need to pull fuses until you can find one that MAKES THE TESTER LIGHT GO OUT during this test.

There are two fuse blocks and one Fusible link buss block at the Battery.

Best to start with the easier one - under the hood. This one is used by the PCM but sends power to the BCM inside the car.

Inside the car is the BCM.​

- one that the BCM uses - is powered from the main fuse block the PCM uses under the hood.​

The BCM also has a Fuse Block of its own. To power itself from the vehicle and it also uses this same block, from itself, to branch off to circuits it operates - Power Doors Windows - even the lights. SRS, CAN even SYNC.​

• - Grab your owners Manual and Locate your fuse blocks - both inside the car, and under the hood.
• You can try locating specific fuses of the larger amp ratings and pull them first, if the light goes out - you found the system causing this condition - but not the real sub-system that has the fault.
• If the Light doesn't go out, reinstall fuse and proceed to the next one.
• Do this using the Owners manuals layout as a guide to help find the system causing this condition.
• If you can't make the light go out - the fused side of the electrical system may not be the problem - but it is the easier system to check first.
• You may need to locate the main terminal RED BATTERY TERMINAL cover and remove it to expose the Fusible links and you'll need to unbolt those to see if the light goes out. If you're not comfortable with this step - you don't have to do it - but keep in mind this system may be the one causing the fault and will expose you to a continuous drain and dead battery problems until you get it serviced.

The PCM Takes care of most of what is under the hood and goes thru the Hood Fuse Block assembly.

Some Climate control goes thru both the PCM and BCM to handle FAN, A/C - Heat - uses the Engines PCM to provide the A/C compressor and clutch to operate and cool thru the Climate Controls - but uses the FAN Heater and Which vent to blow air thru - thru the BCM.

The Dashboard, Instrument Cluster and Center Console use both BCM and PCM directly as idiot lights and Gauges, and also thru CAN as a means to share, store and update systems.

So Fuses power a lot of different sub systems as well as the main ones - so not all fuses will have power thru them because of the main fuse or relay that the PCM or BCM use to direct power - does not always provide power for the subsystem at any given moment.

It is this condition that may occur when the system affected by it - receives power and never shuts off. It can cause a cycling condition or worse a stuck, binding condition for a servo or motor to then seize and basically prevent itself from moving a cam to move a lever of a switch to tell the system to turn me off.

So you may need to see if the Fuses can receive power - like they should - or receive power when they should not. A Circuit Tester can help with this.

The Tester "clip" is clipped to the Ground Bolt, or known frame bolt of/For/To ground if you have to check the BCM (inside car).

The Tip of the probe only has to touch the "tip" of the fuse metal exposed at the number of the amps the fuse is...

Test both sides!
If the Tester lights on both sides
the FUSE is POWERED and still GOOD
But should it get power ALL the Time?
Read the Owners Manuals ' section on Fuse, their location and function.​

If there is power flowing into the Fuse, it will light the Lamp - the Tester lights because it is connected across the power source and to the Ground point you clipped to.

That is where your owners manual comes in, you will have to find the circuit it is assigned to and can help troubleshoot the problem.

IF say, the BCM is using power, but sending it to the Climate Control system when the key is OUT of the ignition and the Car should be off, you can pull the Fuse that works this sub-system and have the system checked - pulling the Fuse is a TEMPORARY solution to keep the Battery from draining and you getting left stranded somewhere.

 

[ged65]

Thank you every one of you for your kindness in taking the time and trouble to advise me, even going so far as to include pictures. I have taken it all onboard and as soon as I'm feeling a little better (I'm having a nasty flare up of colitis at the moment) I will ask a friend to help me and I'll see if we can get this problem sorted for Rosy. I can assure of behalf of Rosy and myself that we are both very very grateful for your help. Regards. Gerald

 

[Handy Andy]

Keep us posted, sorry to try and cram a Class of Electronics 101 - into a single post, but if it helps then by all means - you're welcome...

 

[ged65]

Hello, Sorry it took me a while to get back but as I said it was due to ill health. I promised an update so here it is. After several investigations it was discovered that there was an intermittent alternator fault, when the engine first started it gave an output so looked as though it was ok, but a few moment later on checking again it was giving out nothing, so she has had it replaced. However she still has a problem, a strange one which I don't know if anyone knows the cause of this and I'm hoping nobody will mention the dreaded words, Body Control Module? After replacing the Alternator, when the engine is started, neither the Speedo Nor Rev counter work for something like 15 to 20 seconds, it's strange, but is it anything to worry about?

 

[Handy Andy]

In light of this as possibly reawakening a dreaded Gaila Monster of "Dead Thread - Re-Threaded"

The Cluster itself uses a low-voltage battery backup and in the symptoms, the cluster that looks for data, that has to come thru in the wiring - some wires are from the BCM, while others are from the PCM and in Automatics the TCM.

So, the cluster Head Information Display - that is located in this module (your PODS not the other one), may have issues of lack of power to communicate - suffered damage from the Alternators demise - or due to a repair, or the communication network it uses, is compromised.

That delay can happen for many reasons but when the that Alternator failed - a surge or poor voltage regulation that the battery could not absorb those swings a bad regulator on an alternator can cause - may have damaged the communication bus the cluster needs - not to be outdone - the cluster then tries to establish a link using a protocol - if the link fails another attempt is tried - and also the PHYSICAL connections that direct to the other "heads" if they don't work - should set a code in the Pods own DTC storage - and you'd find that by placing the Pod system in TEST mode - a leave it there for those few minutes to help it diagnostic - diagnose and display or store the right code it is encountering.

So that means you'll have to push that trip reset button and turn the key to on, let it "boot" into "TEST" on the display - then you're to go ahead and start the car and even drive it if you can, to help in this discovery of that communication handicap.

It could be something that you have a corrupted memory failure in one module - that will show up in the DTC section of your test mode. - it may localize the corrupted memory and just replace that module.

The system attempts to "backup" itself using a power-down sequence that arrives to a consensus - all parts working and equal all the data stored should be correct. IT won't store a DTC or attempt to "hide" one if there's nothing wrong, but it may create a DTC code you may not understand or even be able to research for the code is specific to a type of error-processing condition and may also flag tampering - which would be an internal fault generated by the system it can't process but in the length of time to run the diagnostic in itself it can sense other subsystems, load their data and process it as current data. Simply due to the fact that it cannot verify its own stored memory is correct.

It is my hope that the DTC flag is simply a bad data issue, and it can be fixed by a simple clear and reset that might have to be done at a dealership for the one subsystem is not recognized or recognizing the others until it passes a self-diagnostic and it can't clear the code due to its corrupted memory.

How I came to know some of this is from a day I had to spend time working on the rear brakes - of all places - I set a light on the dash and began a process of locating the DTC code and it helped be decode the error to an ABS sensor - I had put it in, but I did not do it correctly.

So, as I took to the task of fixing the fault, the other things I was taking apart including the dash to help with a steering column problem, so I had to take the pod assembly out - it was during the reinstall of clearing the fault and putting the pods back in, did I find that if it lost connection to the battery keep alive voltage and the bus-system - it acts "stupid" until it re-establishes itself in the system.

It is my thoughts that the instrument cluster or the pods cluster - is having trouble keeping itself alive for it is unable to know how to process the data until it finally boots and establishes contact with the rest of the system. Then it seems to work normally.

 

[scotman]

It's a relevant topic. I have revived a few older posts myself. If the question was well stated and didn't get a good reply, the discussion is still important.
People need to understand that a steady, clean supply of electricity, even if it is in very low voltages is critical to the reliable operation and long term functionality of our Fiesta's.
A ranging voltmeter is our best friend when trying to find the cause of many problems.