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Author: Subject: MOT & Battery warning lamp
bonzoronnie

posted on 5/4/19 at 12:40 PM Reply With Quote
MOT & Battery warning lamp

Hi Chaps

I know some of you are well versed on the new MOT regs

What is the situation re: battery warning lamp being lit when the engine is running.
MOT fail point or advisory notice.

For those of you that are interested, 06 Ford focus 2 litre TDCI.

Car was given to me by my eldest, battery light was on when he gave it to me.

I ran my Forscan software to look at the fault codes & the codes showing were the charge system ( Probably wiring related )

Car has done 1.3k miles since I had it & battery is still fully charged, that kind of rules out the alternator.
I suspect it is a Ford smart charge issue, related to wiring.

Other than a minor intermittent misfire on idle, car drives great & pulls like a demon compared to my old Grand Cherokee 2.7 CRD
Saved me a fortune on fuel that's for sure.

Why not just fix it I hear you ask, short answer, just been to unwell to be messing about under a car bonnet.

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rusty nuts

posted on 5/4/19 at 01:00 PM Reply With Quote
Been out of testing for a couple of years but I would have passed and advised .
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starterman

posted on 5/4/19 at 03:24 PM Reply With Quote
It will be a smart charge alternator and the reason that the battery hasn't yet gone flat is that the alternator will charge at about 13.8 volts when not working correctly. The ignition light being on means that the alternator isn't functioning correctly. First place to start is the wiring plug and/or the short piece of wiring between the alternator and the main loom. Normally the light on will mean an MOT failure but if your tester is sensible then he will only advise it.
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steve m

posted on 6/4/19 at 07:32 AM Reply With Quote
I was under the impression that the warning lights failure was for safety critical items as in SRS, Airbag, MIL

I cant understand why a car would fail, if the charging light is on,

why not take the bulb out?

steve





Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at




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rusty nuts

posted on 6/4/19 at 09:40 AM Reply With Quote
quote:
Originally posted by steve m

why not take the bulb out?

steve


Possibly an LED thatís part of the printed circuit? Also some alternators need a bulb to excite them so they charge.

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rusty nuts

posted on 6/4/19 at 09:40 AM Reply With Quote
quote:
Originally posted by steve m

why not take the bulb out?

steve


Possibly an LED thatís part of the printed circuit? Also some alternators need a bulb to excite them so they charge.

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bonzoronnie

posted on 6/4/19 at 10:51 AM Reply With Quote
Cheers for the input guys.

Starterman

I did a fair bit of reading on Fords smart charge system and as you say, charging as a normal alternator due to a fault in the smart charge system.

Prefer to investigate the wiring before shelling out for a new alternator which looks like a pig of a job to change.

Steve

I expect removing the bulb ( If Possible ) would cause the check engine light to come on as I believe the instrument cluster is linked to the ecu on the Focus.


Health wise, I am getting a bit more mobile so hope to sort it out in the very near future.

Mot due next week and buy sods law, my boat is due to go back in the water next Saturday.

What energy I have is being spent on the boat at the moment.

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big_wasa

posted on 6/4/19 at 03:02 PM Reply With Quote
As your man above says plug and the first 150mm of loom are the most common suspect.

I may have a spare if yours is faulty.

On a post 2000 ford there is no connection between alternator and dash. Itís all on the bus.

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bonzoronnie

posted on 6/4/19 at 06:26 PM Reply With Quote
This afternoon the sun was shining & the cold wind had gone so I went for a quick delve under the bonnet of the Focus.

Pulled the alternator plug, stripped back some of the cable trunking & inspected the loom.

As Starterman & Warren suspected, a break in one of the wires to the smart charge loom.
Unfortunately just as the wire enters the plug.

The red wire is the one broken, from a wiring diagram from the net, that one is the +ve feed from the battery & the other Two are the CAN bus signal wires.

Warren.

Many thanks for the offer of a plug, junior has ordered me a new plug with tails from the web.
Under a Fiver, what could possibly go wrong.

May take you up on your offer if it turns out to be a lemon.

Many thanks for your sage advice, with a little luck a new plug may solve the issue.

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starterman

posted on 8/4/19 at 01:39 PM Reply With Quote
I see you are in SW Cornwall. I'm in Callington so if you need anything or anything tested then give me a call (07964773207). I'm here to help
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bonzoronnie

posted on 9/4/19 at 06:30 PM Reply With Quote
quote:
Originally posted by starterman
I see you are in SW Cornwall. I'm in Callington so if you need anything or anything tested then give me a call (07964773207). I'm here to help


Yes, down is sunny Penzance

New alternator plug arrived this morning.
Had a spare hour & changed it.

Charge light now working as it should.
It would seem that the issue is now solved.

Just got to find whats causing the intermittent rough idle.

Many thanks for your offer of help, it is much appreciated.

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