Electrical issues

[ritmo]

Thanks all for responses to my Turbo and axle leak issues. However, I'm having trouble getting past the first hurdle which is stopping me look further into the other problems.

The thing that's actually stopped Betty is electrical.. I have been noticing problems lately with the alternator not charging the battery. I spent a lot of yesterday filing around with wires and a volt meter, but at a loss as to my problem. I initial thought it was the old alternator and replaced it (last year) with a newer Valeo alt from a C5, alt seems to be good, because when it works it works fine. However sometimes it's not kicking in and charging. Should also note, I have a good 2 year old Bosch S3 battery, more than enough to beast her into life.

Was away over the weekend and had trouble starting (starter not even turning over engine, push starts!). On the way home I noticed the battery was getting low (alt not charging), lights going seriously dim. Just managed to get home with the battery down to around 10V

My suspicions lay with the "feed" voltage to the alternator. I thought maybe the battery had got so low it wasn't feeding the alternator enough volts to boost it up to 14v. I recharged the battery after which the volts between the "feed" port of the alternator and negative was 7V with the ignition engaged. I'm not sure what voltage this is meant to be but at least there's something there. So having charged the battery I expected to at least be able to turn over the engine. Nothing. I can hear a relay clicking in the glovebox area, but it's not even engaging the starter.

Maybe a dead starter?! Delved down to the starter motor and attached a cable to the solenoid ignition feed and ran it to the battery. Engine turns over! So the problem might be upstream somewhere... Head scratching. I don't know where to go from here...

Other electrical symptoms have been:

- buzzing relay (in glovebox area) on hazard lights with difficulty turning them on
- engine cooling fan noticeably dimming the headlights when it's running (before the latest fatal issues).
- while doing tests yesterday, weirdly the hazards would come on when I turned the key. However, the hazard relay in the glovebox isn't going. There is a relay sounding behind the dashboard. Very strange. Are there two relays for the hazards?

Sorry it's such a long message. I'm just a bit baffled as to what the hells going on.

Thanks for any pointers...

[KevR]

First thing: check all the earth points are clean and tight.All sorts of mysterious electrical problems, especially lights not behaving as you expect, can usually be traced to lousy earths. Also check that battery connections are tight - the original lead clamps on BX leads are soft and prone to stretching and eventually breaking.
Low voltage at the starter solenoid terminal when you turn the key (due to corrosion in switch and wiring) can stop the solenoid working properly. Fitting a relay triggered by the original starter feed and supplying power via fresh wiring should cure it. There's also been an example on here failry recently (to my shame I forget who did it) of fitting relays for all the power feeds from the ignition switch, to make sure the whole system's working as it should.
Intermittent charging faults are often down to a worn slip ring and/or brushes on the alternator. If a sharp tap on the body of the alternator (using a long metal stick tapped with a hammer) suddenly perks up the charging system when it's not behaving, then that's probably the trouble. New brushes are easy-ish to fit in the original BX type alternator and can compensate for a worn slip ring (slip rings are cheap, but a bit more difficult to change), not sure if the C5 type is different.

[electrokid]

Not sure whether this is particularly helpful - but there's no 'feed' connection to a BX alternator - most modern alternators are 'self exiting' and also self regulating. The only connections are the main feed to the battery and a smaller wire going to the warning 'ignition' light in the dash. Some alternators have a variety of small connections though so make sure you have the smaller of the 2 wires going to the right connection on the alternator.

[KevR]

Good point!

[mat_fenwick]

The guide to fitting ignition switch controlled relays is here. Arguably, if the only problem is with the set of contacts in the ignition switch which operates the starter solenoid (and IF that is the cause of your problem), you could just fit one relay.

[KevR]

That's what I've done so far - it's cured my intermittent starter solenoid woes.

[David]

I would recommend doing the relay mod that Matt suggested first. It cured a clicking starter motor for me.

BUT it isn't a magic fix for everything, Check the wires between the starter, alternator & battery, & the earth between the battery & gearbox. They could be internally damaged & causing high resistance. Check the connections & if is isn't charging check the actual alternator.

Also don't rule out a battery because it is new. I had this over the weekend, my BX wouldn't start after putting the gearbox back in & after having everything in bits it was the battery!

Hope that helps.

[electrokid]

The need to fit a relay is probably a symptom of there being dirt / muck / oil in the starter solenoid itself so purists among us (?) may want to take the starter motor apart and clean it thoroughly.

It's probably a damn sight easier to fit the relay

[mat_fenwick]

The need to fit a relay is probably a symptom of there being dirt / muck / oil in the starter solenoid itself so purists among us (?) may want to take the starter motor apart and clean it thoroughly.

I did But with no change. That may well be the usual case, but with mine it seemed to be voltage drop across the ignition switch contacts (and probably elsewhere too). I measured around 6 volts at the solenoid on the trigger wire! Still addressing the symptoms rather than the cause, admittedly...

And I agree that simply fitting a relay is not a magic cure-all - the fault may well be elsewhere as David suggested.

[ritmo]

Oh god!

Lying half sleeping in bed. Just struck me what might be causing the issue... The car has an immobiliser alarm. Because the battery was flat I may not have even disabled the alarm with the fob and just accessed the car with the key. Would explain hazard lights flashing. Don't know why the alarm wouldn't have sounded, but this seems most likely to me.

Probably still an issue with the alternator not charging. But fingers crossed will at least turn over the engine tomorrow.

Probably shouldn't be admitting such stupidity!

Will update tomorrow after work.

[NeilGP]

Check the engine earth strap. This links from the battery clamp onto the engine block.
If this is broken or frayed then you do not get a good circuit to feed to the starter or from the alternator.

If you do have difficulties starting just put a jump lead between battery earth and engine block and see if this improves things.

[Defender110]

Oh god!

Lying half sleeping in bed. Just struck me what might be causing the issue... The car has an immobiliser alarm.

Rip it out and start again! (Great song by Orange Juice in the 80's)

[electrokid]

I did But with no change. That may well be the usual case, but with mine it seemed to be voltage drop across the ignition switch contacts (and probably elsewhere too). I measured around 6 volts at the solenoid on the trigger wire! Still addressing the symptoms rather than the cause, admittedly...

So fitting the relay gets rid of the symptoms from several different causes... which is why I think its such a damn good idea

[KevR]

The car has an immobiliser alarm.

Rip it out and start again!

Yes, ditch it ASAP - first thing I do when I get a bike or car with an aftermarket alarm. I loathe and detest the bloody things. The trouble they cause always outweighs any tiny anti-theft value they may have.

[citronut]

have you checked the condition of all the terminals at the plug block under the battery tray,

this is the main engine loom connecter to the main engine bay loom,

a customer of mine owns a dark blue diesel estate,

he had starting problems several times whilst out and about,

he called the break down company out on three different occasions,

he had been told the car needed a new battery then a starter,

on going to there house to get it started it turned out to be the solenoid connector in the said plug connecter under the battery tray

regards malcolm