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Multiple module failure all at once. Alternator?


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Car: 2012 Focus Mk3 Titanium 1.6 TDCi

Hi all. Two weeks ago, the car decided to go a bit crazy all at once. I've got a lot of simultaneous module failures, which are:

- Stop/Start
- Traction Control
- ABS
- Hill Assist
- Adaptive Cruise Control
- Forward Alert
- Lane Assist

The car drives fine, having driven it to and from the garage on a stretch of motorway. The first thing that popped into my head was the battery, but this has been tested four times at two different garages - even after being left standing for a week at the garage - and it's passed. The voltage is 12.4v, but goes no lower than 12.2v when left for a long period. It's also only 2 years old.

Testing the voltage at idle, it's still only 12.4v. I know these cars presumably all have Smart Charge and this readout would make sense, so I tested again under load with everything on (front and rear heaters, AC blower on full, headlights on), but I'm only getting 13.2v from the alternator. That's under as much load as I can give it.

I've got an Autel computer that can read and clear the module codes. After clearing them, they come back 30 seconds after starting the car. I haven't actually read the errors yet, I really should do that...

My guess is that it's a bad alternator, as 13.2v under full load sounds low, but I'm wondering if anyone could also shed some light?

Thanks!

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3 minutes ago, Jimpster said:

not aufait with Autel, most would recomend FORscan or ELMconfig, have you considered a cluster issue ?

I haven't, due to the stop/start button also being illuminated, which isn't part of the cluster. The Autel also shows faults on all of these modules and has no cluster fault. The faults can be cleared, but return after 30 seconds of driving. The voltage is also low for an alternator, so none of this particularly points to a cluster failure. Good suggestion though.

I had a similar problem when I bought the car 2.5 years ago, the car started to freak out. A new battery and resetting the modules had cured the issue. Modern cars with stop/start tech tend to go a bit loopy when the power delivery drops below a certain threshold, which seems to be what's happening again.

I'm convinced it's an alternator issue, but want to see if anyone's got any insight or any other ways of testing to confirm it before I go purchasing parts. For instance, a friend mentioned that it could be a wheel sensor issue - stop/start needs to sense if the vehicle has stopped, and most of the other errors rely on information about the speed of the car. But it was the 13.2v that's convinced me at the moment.

Unless anyone has any other suggestions?

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get the alternator tested find a local that can test avoid main dealers, some will do a px against a refurb unit. Its gonna be a trial and error kind of fix hopefully the cheaper end will sort it.

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Update...

I disconnected the negative for a few seconds, then re-connected it, purely to see the results. All of the dash errors disappeared aside from the ABS. After plugging in the Autel and erasing all of the previously displayed codes on the modules, the car was back to normal.

I sat on the driveway for about 15-20 minutes with the aircon on, front/rear heaters on, occasionally revving the engine to put stress onto the alternator, but it remained fine.

Until I drove off the driveway. It must have reached 10mph before all of the errors sprung back onto the dashboard.

Now that's got me thinking that it's a wheel sensor issue. Thinking about it, all of these errors could well be connected to a wheel sensor. Stop/start needs to sense if the car has indeed stopped, TCS and ABS are obviously connected to wheel speed, same as cruise control. Forward alert possibly, perhaps when it applies the brakes. Lane assist and hill assist, possibly.

I'll keep digging, but is there any way of diagnosing a bad wheel speed sensor?

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2 minutes ago, geraintthomas said:

I'll keep digging, but is there any way of diagnosing a bad wheel speed sensor?

Does your scanner show live data?

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Just now, geraintthomas said:

It does. What should I look for?

ABS sensors.  It would be ideal if you can run a live data graph with all 4 sensors individually.  That way we can see if one is reading well out of range in a straight line.  I don't know if that information is available though.  If not, you'll have to check the sensors manually with a multimeter.

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Just now, TomsFocus said:

ABS sensors.  It would be ideal if you can run a live data graph with all 4 sensors individually.  That way we can see if one is reading well out of range in a straight line.  I don't know if that information is available though.  If not, you'll have to check the sensors manually with a multimeter.

I was thinking multimeter, but I'm not too sure what I'm expecting. A constant voltage between the two pins, looking for the one that's reading over/under the rest?

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Just now, geraintthomas said:

I was thinking multimeter, but I'm not too sure what I'm expecting. A constant voltage between the two pins, looking for the one that's reading over/under the rest?

Well, this is where it gets more difficult.  As the sensor isn't bad enough to have flagged a specific fault code, that suggests the sensor/wiring isn't totally dead which would be easy to spot with a MM.  It will still give a reading, just not an accurate one.  So voltage readings need to be compared when turning each wheel.  But turning each wheel at the same speed by hand won't be easy either.  I'd much rather use live data while driving straight ahead if that info is available.

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Tom, as far as I know the wheel sensors don't give a voltage proportional to speed. I think they're Hall effect which give a pulse train generated by the toothed inductor ring, but maybe someone knows better.

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1 hour ago, mjt said:

Tom, as far as I know the wheel sensors don't give a voltage proportional to speed. I think they're Hall effect which give a pulse train generated by the toothed inductor ring, but maybe someone knows better.

Fair enough.  Ford haven't used toothed rings for 20 years though.  They use magnetic rings in the wheel bearing.

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They're magnetic rings in these.

Update...

I took both ABS sensors out. The nearside sensor was completely covered in gunk, whereas the offside sensor was fine. I cleaned them both regardless, and inserted a small brush into the hole to clean any debris that may be on the rings. Re-fitted, wiped the codes, but they came back the moment I pulled away from the house.

I did two more tests. One where I wiped the codes and waited for 20-25 minutes outside the house, putting stress on the alternator. The car was fine, until I pulled away. The next test I wiped the codes, and after starting the car I pulled away straight away without waiting around, and no surprise they came back straight away the moment I pulled away. It's definitely coinciding with the speed of the vehicle.

Given that ABS sensors on the fronts are about £10, I'll go ahead and replace them both, considering I've already got them loose and out of the hubs. If one has failed, the other could follow. For that money it's probably worth it.

I'll let you know what happens once I replace them.

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4 hours ago, TomsFocus said:

Ford haven't used toothed rings for 20 years though.  They use magnetic rings in the wheel bearing

Ok, I didn't know that. Nevertheless if the sensor is a Hall effect type it produces a voltage proportional to the strength of the field so a simple magnet would not give any signal related to speed. I'd guess the magnetic rings consist of alternating north and south poles which will give a pulse train whose frequency is related to speed. Even if the sensor is a simple induction coil the same would apply. A pulse train is a more reliable method of measuring speed - important since the speedo now relies on it - as it isn't affected by any voltage drops in the cable.

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My thoughts are the battery / charging system is faulty.

The battery voltage at only 12.4V is too low, it should be sitting at around 12.65V. So the first thing that can be established is the State Of Charge (SOC) is low. The next question is to find out why.

The alternator should be providing at least 13.6V at a steady idle and typically around 14.8V when at a fast idle.

To check the alternator smart charge system simply unplug the small connector on the side (sometimes back) of the alternator. This will cause the alternator to immediately switch to the standard default charging mode of 13.9V If the alternator output is less then it is fair to say it is defective.

SOC.JPG

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41 minutes ago, mjt said:

Ok, I didn't know that. Nevertheless if the sensor is a Hall effect type it produces a voltage proportional to the strength of the field so a simple magnet would not give any signal related to speed. I'd guess the magnetic rings consist of alternating north and south poles which will give a pulse train whose frequency is related to speed. Even if the sensor is a simple induction coil the same would apply. A pulse train is a more reliable method of measuring speed - important since the speedo now relies on it - as it isn't affected by any voltage drops in the cable.

Fair enough.  So is there any multimeter test that can be used to check the varying speed on the sensor?  I would have suggested a basic resistance test for a totally dead sensor but that's not the case here.  (And may also be wrong anyway lol).

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I've just replaced the two front ABS sensors, and it still hasn't fixed the problem.

It still has to do with speed. The errors only appear the moment I start moving, and not at all when idle, even after stressing the alternator.

To add to this, whenever the car is turned off, then back on again, the only lasting dashboard light is the ABS light, which is making me think an ABS sensor fault. All other modules aside from stop/start can be turned back on successfully when restarting the car (forward alert, lane assist, etc). When moving, they all fail again.

I'm wondering whether it could be:

- The rear ABS sensors
- The alternator not giving enough power to the modules that use the car's speed. When the car moves and those modules are in use, it freaks out.

Here's a video:

I'm not sure what to try next. Any thoughts?

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I am not an expert at all, but I did wonder when you said that as you suspected ABS sensors you were going to replace them BOTH. I thought you were going to say "all 4". So yes, maybe replace the rear two too

Then, could it be the ABS module/pump unit?

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I haven't tried with your model of car but FORScan can normally give you a live readout of individual wheel speeds when driving via the ABS Sensors plus a lot of other useful Live Data.

You should also be able to get a Live reading of the Voltage at least at the BCM and possibly the Voltage at some of the Modules as well. 

Spending £20 on a cable makes more sense than replacing parts that may not be faulty.

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3 hours ago, Tizer said:

Spending £20 on a cable makes more sense than replacing parts that may not be faulty.

but guessing keeps this thread going much longer, and it helps keep the parts industry in business 😉 

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The same thing have happened to my car over the weekend, have had a diagnostic done today comes up rear wheel sensor, been ordered apparently there are different ones, if you have abs-t/c hill- assist ,stop/start and so on, told look at the colour of sensor needs to be the same   Will have to wait and see, will up date when its fitted.

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Thanks for that reply UNOFIX,  follow up for my post had the rear sensor done today and Guess what happened that's right every things back as it should be I still cant believe one sensor can bring on so many lights and warnings and took all of 10min's to fit. HAPPY DAYS

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Hello all I wonder if this is what I need to do to cure my similar problem

I have 2011 Titanium X and the initial fault came up

Tyre Pressure sys fault - service required

I now have

Hill start assist not available

The stop start light permanently on

Auto park malfunction if I try to use it

 

 

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