Cutting out when headlights on full beam

[zcacogp]

Chaps,

A quickie. Just driven my S2 on a 150-mile round trip (and loved it - it's not driven much these days, and I miss the fun!) The weather was grotty, and I had the dipped beam, heater, radio and a couple of other things on. And, to my consternation, discovered that it cuts out when you turn the headlights on main beam (flashing someone to indicate that they should pull out.) The engine stopped firing and radio turned off, but it all came back on (and - presumably - bump started itself) when I let go of the 'flashing' stalk.

I am guessing that this is simply a matter of the load on the system being great to the extent that the coil isn't getting enough juice to produce sparks, but given that the alternator was new a couple of years ago, and the voltmeter shows a tiny smidge under 14v when running (even with all the electrickal bits on), I am guessing the problem is a bad connection somewhere between the battery and the front of the car - either on the +ve or the -ve (earth) side of things. Is this a reasonable guess?

Presuming it is, where should I start looking? Battery leads, battery earth strap, engine earth strap, connections on the back of the starter motor ... anywhere else?


Oli.

 

[Copperman05]

Didnt you re-wire your headlights or something? Could this be the issue?

Edd

 

[zcacogp]

Edd,

Well remembered. Yes, I did, but the car was fine after I had done it - it was a couple of years ago now, and this is a recent problem. It will be relevant as the bigger bulbs will gobble more juice, but the increased wattage of the bulbs (60W up to 100W each side, so total increase of 80W) isn't that great in the scheme of the total power consumption of the car.

Good spot tho'.


Oli.

 

[Copperman05]

Would a short circuiting of the electrical system cause this sort of issue? Seems plausible considering the complete momentary loss off power to everything, cant say I've ever experienced something like that though.

Edd

 

[zcacogp]

Could be, but if it was short-circuiting then the current flow would be massive, leading to either something getting seriously hot (and probably a fire), or (more likely) a blown fuse.

Oh, and another point I failed to add - it doesn't happen every time I flash the main beam. Sometimes it does, sometimes it doesn't.


Oli.

 

[Lowtimer]

ORIGINAL: zcacogp
Could be, but if it was short-circuiting then the current flow would be massive, leading to either something getting seriously hot (and probably a fire), or (more likely) a blown fuse.

Not necessarily - that depends what it is shorting to. If it is shorting to a path with high resistance the current flow might not be very high at all. Which is just as well. I suspect you have a cracked or worn wire somewhere in the wiring around the steering column.

 

[Frenchy]

Switchgear (stalks) or ignition switch, i say this as a lot of modern cars have all sorts of problems with electrical loading, i know from experience.

 

[simkin911]

I've had weird & wonderful problems with switch gear before but never engine cut out..... although did have other electrical issues.

ps - hope you're doing well old bean!

 

[zcacogp]

Chaps,

Thanks for he answers. Chris Grahame has texted me to suggest it's the writing up into the headlight pods, but this is 2 years old (replaced when I put relays into the system) and done with specially flexible wire (low-temperature cable.) SO I don't think it is this.

So the consensus of opinion is that it is the wiring in the switchgear or the steering column. What's the best way to tackle this? Take it off, I guess, and eyeball it ...

Thanks for the suggestions.


Oli.

P.S. Steve - yes, doing well, thanks. How's your turbo coming along?

 

[JamesO]

Have you tried switching other high current loads on and off quickly such as the heated rear window? Is the battery in good shape? Time to break out the multimeter.

It is strange, did you feed any gremlins after midnight?

 

[zcacogp]

James,

That's a very good idea - trying other loads. I'll do just that, next time I am out in it.

I feed myself fairly regularly after midnight. And the cat. Do you think that could be the problem?


Oli.

 

[colin944]

My 924 used to do all sorts of things like that. I used to call her christene because of all th elittle electrical gremlins. Lights going off at night on a twisty road at some mph was always a good one.In the end and after a lot of poking around and changing most of the wiring I changed the fuse box................ end of problems!!!!!!

 

[NeilW]

I had something similar with my two previous 944s. The whole vehicle would suffer a loss of electrical power. If the car was running at the time then it sustained itself using the alternator; if the engine was off then the whole car went dead. After much troubleshooting it turned out to be the positive battery cable connection. Cleaning/sanding the ring connector didn't solve it, I had to cut the lead back an inch or so and affix a new connector. Good luck.

 

[zcacogp]

Neil,

Helpful stuff, thanks.

I'll update this thread when I have found time to look at the car and diagnose it.


Oli.

 

[zcacogp]

Haven't tinkered with the car yet, but drove it again a couple of times at the weekend.

Observations;

1. Flashing the main beam when the headlights are not on doesn't cause the engine to cut out. (I can't say it never does, but it didn't when I tried it 10 or so times.)

2. Flashing the main beam with the headlights are on often causes it to cut out (but not every time - sometimes the revs dip but the car 'catches it' and all is fine.)

3. I couldn't recreate the symptoms solely using other electrical accessories (heated rear window, fan, radio, dipped headlights, foglights etc all on at the same time was fine.)

4. Having the main beam headlights on (with the stalk pushed forwards) seems fine as well.

I think I need a long session cleaning up all the major electrical contacts on the car ... deep joy, just when the weather is meant to be getting cold as well ... []


Oli.

 

[zcacogp]

Update on this one; I spent an afternoon earlier on this week taking various electrical things out of the boot, cleaning them up and re-installing them. This involved the battery and a small audio amplifier i have in the boot, and the cutting-out problem did seem worse when this was on (I guess because it was using juice). I did the following;

- Removed and cleaned up the battery earth strap, and re-attached it
- Removed and cleaned up the battery live terminal, and re-attached it
- Removed and replaced the connection from the battery to the amp live lead
- Made a new (better) earth connection on the bodywork for the amp earth lead

And ... fingers crossed ... it seems to have cured the problem. Additionally, the car starts more readily (spins faster on the starter motor) and seems to run significantly more smoothly! My guess is that the battery earth lead connection to the bodywork was less-than-great (although it looked fine, and registered a resistance of 0.00ohms when measured with a DVM) and a good clean of it has helped a lot.

Nice that it was a simple fix. Shame I didn't tackle it earlier!

Thanks for your suggestions.


Oli.

 

[Hilux]

OT comment

Oli

Re your signature(s)

Why betting companies???

I have no issue I am just curious thats all.

 

[zcacogp]

Paul,

See here:

http://www.porscheclubgbforum.com/tm.asp?m=671488

(It won't last long as as gag, but the old signature was looking a bit tired ... )


Oli.

 

[944 man]

Oli, everything turningoff sounds like a main earth strap issue. I had similar once in a diesel and the lights went out and the glow plugs came on for five seconds...

Even if not then youll have spent little and done a job that will have needed doing, even if it hasnt solved the current problem.

 

[zcacogp]

ORIGINAL: 944 man
Oli, everything turningoff sounds like a main earth strap issue. I had similar once in a diesel and the lights went out and the glow plugs came on for five seconds...

I think it was, but is now fixed - thanks. (See post #16).


Oli.