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Post by valhalla on Apr 2, 2015 0:02:18 GMT 1
Does anyone know what the alternator feedback voltage from the field control unit in a Ford smart-charge system should look like? I have a Mondeo diesel on a 2005 plate that is on its third alternator (first time I've seen it today), but unfortunately I think it's going to need a fourth.... Attached PDF of the oscilloscope trace shows the voltages at the three pins to the alternator control plug; Blue channel_A is the 12v supply pin3(orange/yellow), red channel_B is the PCM control line pin2 (brown wire), and green channel_C is the PCM feedback wire from the alternator pin1 (white). I'm sure that there is some continuity back to the PCM from the alternator, as the pins 1 and 2 are both affected as the multi-plug is closed together (voltages pull-down a bit). All the references seem to show the alternator feedback as around a flat 0v when the engine is idling under no electrical load, but I am seeing around a flat 9.5v. I think that the alternator control unit is goosed, but I don't know yet whether the PCM line back to it is 100% continuity or not. Does the alternator feedback need a solid pull-down by the engine controller to give a good signal, or should it read a good pulse feedback open-circuit? Needless to say, the alternator does not charge, the PCM is permanently setting a DTC for the alternator field circuit and going to 64% demand by default (which corresponds exactly on the Picoscope). The alternator does not respond by pulling the control plug either, just no charge. I cannot see a label on this replacement unit, but it doesn't appear to be an OEM, which is the only smart-charge units I've ever fitted in the past to Focus's and the like. Thanks for any help or derision! Attachment Deleted |
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Post by Karl on Apr 2, 2015 7:22:05 GMT 1
I can't see your scope trace ? I use the app
First things first, check the battery, not just condition, but correct type. A lead acid battery will not work properly with smart charge, it must be Silver Calcium Easy to over look.
Next, put a meter across the battery. Remember when you remove the smart charge 3 pin plug from the back of the alternator, it reverts to a conventional alternator! If you do not have about 13.8 volts, carry out basic charging system checks and suspect the alternator, its not a smart charge fault
Correct charge voltage from the alternator, then its time to start on the smart charge system, and you will need a scope. First the system.
Pin 1 = Alternator Feedback
Pin 2 = Alternator Load Request
Pin 3 = Reference Voltage
Now, pin3, must MATCH battery voltage . Its fed from a fuse in the CJB, and a high resistance on the fuse contacts causes a volt drop, and the smart charge drops out
Next pin 1 & 2 need checking back to the PCM for resistance, isolation from ground and each other. If ok, its out with the scope.
Pin 2 is the request from the PCM to the alternator. This will be a square wave pattern that will change with load request. So lights, screens etc on and monitor for a change in the pattern. (Obviously back probing with the plug connected)
No change in the pattern means no request from the PCM, you should now suspect a PCM fault. Correct pattern and move on.
Pin 1 is the feedback from the alternator and MUST remain a constant square wave pattern. If this pattern mirrors the one on pin 2, the smart charge part of the alternator is faulty, and a new unit is required.
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Post by Karl on Apr 2, 2015 7:32:40 GMT 1
Aftermarket alternators for fords are often very problematic, and it's not unusual to hear or have a customer come in who've had multiple units replaced..
Seems especially common on these old mondeo and focus
90% of these are sorted with a new genuine one.
Trouble is a oe alternator is often about 3 times the price of a cheapy reman and I can see why some take there chances
And corroded fuse connections can trip you up.
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Post by valhalla on Apr 2, 2015 10:57:15 GMT 1
Many thanks for both of the replies, Karl.
TBH, I have already pulled the guy up who owns the car, regarding the battery; it was the first thing I looked-at yesterday lunchtime, and a)it's not the pukka item (lead acid) and b)it's the wrong size (too big). Phazed by this discovery, I got straight onto the phone to find-out that this wrong battery has been on since he owned the car, hence his logic for assuming that I can make the alternator charge lamp go out with it still fitted! I approximate it has been on there for at-least four years, whereas his maladies have only occurred over the last 6 months. I phoned him again last night to confirm that I think the battery has been behind at-least part of the repeated failures of two new alternators.
Which brings me on to the next thing, which is that these are real cheapies, an aftermarket brand. I have never come across these before, and certainly would not have quoted a job to refit one!
Thanks for the information regarding dry-joints in the fuse line. I think I eliminated that yesterday, but I'm going to re-check now, because I did have a suspicion that wiring to the smart-plug was not all that it should be (suspect fatigue in the harness adjacent to the cam-cover, where the smart-charge harness bridges engine to body). If I am going to fix this for once and all, I want to be sure that a decent alternator+battery set-up is not going to fail for a year or so!
And finally, the alternator itself is a dud. I made the final measure this morning with the smart-plug pulled, putting the alternator into a default mode, and there's not a dickie from it. No strange currents or anything. So it does appear that the cheapie smart controller in the back of this unit has gone for a burton, but the rectifier stage and winding are possibly OK. Without a field control, this unit is going nowhere except the bin. I cannot say what has killed it, suspicions would be the points you raised regarding the battery, but I need to eliminate the wiring around the car 100%. I still have a gut feeling that something else has caused this latest unit to actually die. Full marks to the Ford designer that positioned the catalyst 4inches from the back of the alternator! I wonder if the car is even running well enough to keep the cat temperatures down?
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Post by valhalla on Apr 2, 2015 11:05:09 GMT 1
Karl, I'll see if I can get the Pico trace file down below 1Mb, so that I can attach it. There's a bug of-recent with the Pico software that means a zoomed file does not open again (it corrupts) and I don't know if the guys at Pico have fixed it yet. The original PDF file seems OK from this end, but maybe I'll try to attach that again.
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Post by Karl on Apr 2, 2015 13:26:13 GMT 1
You say about the exhaust position
Does the alternator fitted have an cold air feed attached ? As the oe item should have a plastic cold air ducking on the side , maybe they are getting to warm ?
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Post by Deleted on Apr 2, 2015 13:59:00 GMT 1
Karl, I'll see if I can get the Pico trace file down below 1Mb, so that I can attach it. There's a bug of-recent with the Pico software that means a zoomed file does not open again (it corrupts) and I don't know if the guys at Pico have fixed it yet. The original PDF file seems OK from this end, but maybe I'll try to attach that again. Derision !! your posts mate although long winded at times are the most interesting for me , your waveforms look like its fitted with an earlier alternator than the car year, |
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Post by valhalla on Apr 2, 2015 15:30:18 GMT 1
You say about the exhaust position Does the alternator fitted have an cold air feed attached ? As the oe item should have a plastic cold air ducking on the side , maybe they are getting to warm ? That's a strange thing - the plastic shroud is there, but I noticed (before chucking this one out for a "rest" this morning) that no sign of any trunking is in place. It did strike me that if a plastic tube was not fitted at the factory, it would certainly benefit from a modification to ram air from the front. It sounds like this chap wants me to sort it out, which has to start with the altenator, so I'm going to have a look around and see what I can find. The last Focus TDCi I did, I found a NOS genuine Ford part from a dealer that was de-stocking a little. If I can get a decent alternator, then I stand a chance to measure what is going on and make a call from there. No doubt in my mind, the battery is not helping. It took loads of time for the surface charge to dissipate this morning after the CTEK was switched off. I think the original factory alternator was cooked by the battery, these pattern units have just been "unlucky". |
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Post by valhalla on Apr 2, 2015 15:33:49 GMT 1
Karl, I'll see if I can get the Pico trace file down below 1Mb, so that I can attach it. There's a bug of-recent with the Pico software that means a zoomed file does not open again (it corrupts) and I don't know if the guys at Pico have fixed it yet. The original PDF file seems OK from this end, but maybe I'll try to attach that again. Derision !! your posts mate although long winded at times are the most interesting for me , your waveforms look like its fitted with an earlier alternator than the car year, Now that's interesting......From what I've been told, both replacement alternators were identical make and model, same source, both have failed. What is the best way to tell if the wrong unit is fitted? Given that the present unit doesn't exactly bear much in the way of labelling.... |
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Post by Karl on Apr 2, 2015 18:18:38 GMT 1
Some times there will be a choice of amp outputs , don't think there is on this model though
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french crap fanatic
Apprentice
french car specialist based in dagenham east london
Posts: 3,355
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Post by french crap fanatic on Apr 2, 2015 19:28:31 GMT 1
Very interesting and informative thread.
I'm always asstonished as to how many garages risk fitting non oe equipment to cars,esp electrics and electronics!
On psa cars the sagem systems fitted to some petrol models have sagem coils,when these breakdown they blow the sagem engine ecu!
I also never fit pattern or used parts to vans
Never fit pattern clutch cables
I'm a stickler for using the correct oils as well!
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Post by Monkey on Apr 2, 2015 19:35:26 GMT 1
Pin one is a square wave best viewed at 20v/20ms (I can't see your attachments) and should change with load. An alternator with a waveform mirroring pin 2 with load is a dud.
Common rule is If the alternator is a no charge then the smart charge system is irrelevant, and it's simply a duff unit.
Karl, I fitted a genuine unit to a DV6 focus 2 not long back to find the battery warning light on! Out with the scope and that was no good too!
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Post by valhalla on Apr 2, 2015 20:41:25 GMT 1
Pin one is a square wave best viewed at 20v/20ms (I can't see your attachments) and should change with load. An alternator with a waveform mirroring pin 2 with load is a dud. Common rule is If the alternator is a no charge then the smart charge system is irrelevant, and it's simply a duff unit. Karl, I fitted a genuine unit to a DV6 focus 2 not long back to find the battery warning light on! Out with the scope and that was no good too! Thanks for the feedback. As it turns out, the alternator is just duff, based on the premise above, therefore that's got to be the start. There is no feedback on this one (as far as I can tell) just the sick-looking 9.5v flat line on pin1. What is more sickening, for all parties, is that the regulator itself costs somewhere between 2$ and 6$, depending on how many cases of the thing that you buy from China. For the price of a pint of beer, this unit might well be brought back to life, and that's for a smart-charge regulator (albeit Chinese, but I bet they're all Chinese, even the OEM units!). I'm struggling to find a good alternator at the moment - I've even considered a known good s/h unit to substitute into the engine bay, just so that a better diagnosis of the battery and charging circuits can be made. |
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Post by Deleted on Apr 3, 2015 13:24:03 GMT 1
The reason i mentioned older alternators is in the past i have fitted s/h alt off early car with separate injector control module to a later combined type and couldnt get a feedback signal just astraight voltage not being pulled down by alternator,fit a later one and all ok .. without checking i am not sure if the early modules use a different votage level and frequency compared to later ones  ? if the alternator doesnt pull the feedback line down or at the right frequency you get the warning light [ mystery light]  |
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Post by valhalla on Apr 3, 2015 17:53:02 GMT 1
Thanks for the info Mac! I had a scratch around, and if I go for a very slightly newer revision of the unit, I reckon I can a genuine Visteon part for around £140, plus delivery, and I have advised Mr. Customer to bite the hand off on this one (because I'm not looking any further....). So that's now on order. The part number I think was on the car before all of this fiasco is 1S7T-10300-BC, I'm plumping for a revision CD. So I reckon I'll soon find out if the control or feedback signals changed! The regulator for these things is out there, around £20 off a couple of resellers on a well-known auction site. If it was my car, with an OEM aternator still on it, I would have gone for that instead, as it's got to be the work of minutes to swap over once the alternator is off the car. I might have even been tempted to use an external regulator circuit for this, by extending the field wire back out the side of the alternator, and fixing it somewhere dry next to the multiplug for it on the inner wing. It strikes me that by having the regulator well away from the downpipe/catalyst area of the engine, you could make these Ford alternators a lot more reliable. |
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? if the alternator doesnt pull the feedback line down or at the right frequency you get the warning light [ mystery light] 