Further to my alternator issues post i thought I'd just share a quotation from my ever so friendly Ford stealer to supply and fit a new, genuine Ford alternator for my 21 plate Focus 1.5 diesel which has suffered alternator failure at the astonishing mileage of 1,990 miles ...

£1050 supplied and fitted 😂🤣.

Needless to say I'll not be paying that.

Last price I saw mentioned on here was about 3 years ago and that was around £600 (without fitting) iirc.

Can't get my head round prices any more - last alternator I bought was about £60 (that was 1980 though!😀).

7 minutes ago, Eric Bloodaxe said:

Last price I saw mentioned on here was about 3 years ago and that was around £600 (without fitting) iirc.

Can't get my head round prices any more - last alternator I bought was about £60 (that was 1980 though!😀).

Indeed, I remember selling Lucas alternators for Fiestas and Escorts etc in the late 70's and early 80's for about £40 iirc.

I've sourced a new, brand as yet not known, alternator from a reputable seller on eBay, comes with a year guarantee for £163.

My auto sparky will remove and fit for £60 so hopefully that's the end of that nightmare.

9 minutes ago, MONDEO TXS 2.2 said:

I've sourced a new, brand as yet not known, alternator from a reputable seller on eBay, comes with a year guarantee for £163.

My auto sparky will remove and fit for £60 so hopefully that's the end of that nightmare.

Yes, I've seen a few around that price. I was having a look on there once I'd come round after reading your earlier post!😀

Yes, I nearly fainted at that price 😳

The replacements are all rated at 165 amps max' output, whereas the original fitment is 150 amp.

I can't imagine any alternator being required to generate 150a or 165a for that matter for a Focus.

All the aftermarket suppliers insist the higher output version will fit my Focus without issues.

On most recent Ford models, you can change to a larger output alternator without any problems as long as the larger output alternator is included in the configuration. The type (output) of alternator needs to be changed in the configuration to make sure that the PCM is able to control it correctly. Otherwise, there will be a mismatch between the real charge current and the expected charge current.

On a modern Ford a 150A alternator is barely sufficient. When using functionality like the heated front windscreen, heated rear window, heated mirrors, heated steering wheel, heated washer jets, PTC heater at the same time the current draw will be higher than the alternator can provide. In other words: in these situations you are still draining the battery while the alternator is charging at full power.

7 minutes ago, JW1982 said:

On most recent Ford models, you can change to a larger output alternator without any problems as long as the larger output alternator is included in the configuration. The type (output) of alternator needs to be changed in the configuration to make sure that the PCM is able to control it correctly. Otherwise, there will be a mismatch between the real charge current and the expected charge current.

On a modern Ford a 150A alternator is barely sufficient. When using functionality like the heated front windscreen, heated rear window, heated mirrors, heated steering wheel, heated washer jets, PTC heater at the same time the current draw will be higher than the alternator can provide. In other words: in these situations you are still draining the battery while the alternator is charging at full power.

Thank you for your insights, could you please advise me how to change the configuration ?

Thank you.

This should be possible using Forscan.

I have never done this myself on a Focus MK4 but I suspect that the alternator output is either configured in the PCM or BCM.

21 hours ago, JW1982 said:

This should be possible using Forscan.

I have never done this myself on a Focus MK4 but I suspect that the alternator output is either configured in the PCM or BCM.

Thank you very much.

Could you please explain in layman's terms how the BCM / PCM can differentiate between alternator A, rated at 150a max' output, generating 50 amps of current, for example, versus alternator B, rated at 165a max' output generating the same output. ?

I simply cannot afford the 150a alternator that seems to be the original, failed, fitment.

It's also odd to me that every motor factor in the U.K., that I've found, all list the 165a output version for my car, even the alternator manufacturer Rollco do too.

You clearly have far more knowledge than me, so I would respect and appreciate your opinion.

Thank you in advance.

The PCM uses LINbus communication to control the alternator The PCM is the LINbus master and the alternator control module is the LINbus slave. In other words: The PCM demands a certain percentage of the programmed alternator capacity. The alternator control module controls the alternator in accordance to the signal and gives feedback to the PCM.

If the requested charge rate does not match the delivered charge rate the system will generate a warning message and DTC code. Therefore it is important that the configured alternator capacity matches the actual capacity of the alternator.

At a 50% charge request the original alternator will output 75A while the replacement alternator will output 82.5A. This is a 10% difference compared to the original.

4 minutes ago, JW1982 said:

The PCM uses LINbus communication to control the alternator The PCM is the LINbus master and the alternator control module is the LINbus slave. In other words: The PCM demands a certain percentage of the programmed alternator capacity. The alternator control module controls the alternator in accordance to the signal and gives feedback to the PCM.

If the requested charge rate does not match the delivered charge rate the system will generate a warning message and DTC code. Therefore it is important that the configured alternator capacity matches the actual capacity of the alternator.

At a 50% charge request the original alternator will output 75A while the replacement alternator will output 82.5A. This is a 10% difference compared to the original.

Thank you for your reply.

It seems that I now need FORscan and the appropriate connecting cable, there are links on this site for the software etc enabling me to purchase the correct kit.

Do you know if this process is user friendly or should I employ someone who has the required experience ?

Thank you once again for your help.