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electrical problems

colin smith

colin smith

PCGB Member
Hi i'm looking to get a 964 and have seen on that is in very good condition, but it seems to have a slight problem with the electic. If there is a sudden large current drain ( turning the head lights on etc, it has had a xenon convertion), the lights on the dash covering the 4 wheel drive system come on and the alarm can go off.

The guy selling it seems to think it's and earthing problem, or is it battery alternator????

Has any one come across this sort of problem before?

Thanks
 
Colin,

The 4WD system on the C4 is notoriously sensitive to battery voltage and I wouldn't mind betting that a new battery will solve this problem. Earthing is another area known to cause problems - the earth strap between battery and body is worth checking. The Xenon headlights will take a large surge on startup but actually take less current than regular halogens once alight although I'd expect a healthy battery to handle that OK.

Regards

Dave
 
I would agree with Dave - a weak battery and/or poor contact earth straps. BUT it is worth checking out - if the battery is low then why? If not then why is the current drain so bad? The 4wd lights should not go on just because of a low battery - a current spike may cause it but not just low volts. Did this happen with the engine running?
 
It does do it when the engine is running, but to be fair the battery hadn't been in the car for a couple of months. It all seems very strange, the most unusal fact is the alarm going off due to the current/voltage drop when the engine is running????
 
The alarm going off is not due to the voltage drop I think, but due to the 4wd pressure pump not reaching the right pressure, or an earth leak/spark causing it to trigger. The audible alram going off is a cat 1 stop driving warning - the problem is sometime figuring if the alarm has gone off by iteself or due to a real condition. Does the alram go off after 3000 revs? At that the alternator should take over matters. Always possible the Xenon fitting has a current draw and/or throws a spike that sets the alarm off but why chance it. If the pressure pump take tioo long to reach the operating pressure the alarm wil go but then switch off when matter catch up. If it stays on it is not a good sign.

I think I would get a new battery fitted and see if it still does it. If there is a fault with the 4wd it could be one of 10 or so things ranging from a dodgy connection to a £2+k ecu fail. Worth making sure you don't have the problem before you buy. Most probable issue is wiring and/or dud battery - but be sure before you buy.
 
Great suggestion about the battery. After I had Xenons fitted, sometimes after first switching on, my rev counter would fail!
Now after a new battery, that doesn't happen anymore. I hadn't put the two together.
 
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