Annoying Current Drain

[incorrigible]

Made all the more annoying because it's intermittent

Went to drive to work this morning, turn the key, nothing, not even the fuel pump priming. This is obviously a fault because I took the car for a long run on thursday with no problems at all (and it started on the button after leaving for 5 days)

I'm not so good with 'lectrics, where do I start ?

PS New battery and alternator works fine

[qube]

Made all the more annoying because it's intermittent

Went to drive to work this morning, turn the key, nothing, not even the fuel pump priming. This is obviously a fault because I took the car for a long run on thursday with no problems at all (and it started on the button after leaving for 5 days)

I'm not so good with 'lectrics, where do I start ?

PS New battery and alternator works fine

Mine seems to drain away if left for around a week or so, what i do is if the car isn't going to be used for more than 3 days is to plug the airflow charger in, had no problem since.

[incorrigible]

qube said:Mine seems to drain away if left for around a week or so, what i do is if the car isn't going to be used for more than 3 days is to plug the airflow charger in, had no problem since.

Unfortunately I only seem to have 6 volts at the cigarette lighter so putting the charger on is a pain. Will try some wholesale dismantling tonight. But where should I start ? Battery/fusebox, under the dash ?

[qube]

just checked my ciggie registering 13 volts on multimeter, sounds like you could have a bad earth, or short somewhere, put the lights on to see how bright they are by facing the car against a wall or garage door and start the car, do they go brighter ?,also check the two fan connectors as sometimes these fill up with water if it's been raining, and check your chassis earth strap for corrosion located under centre console drivers side just under dash.

[incorrigible]

Pretty sure the drain isn't round the front of the car, all the power down there needs to be switched on (but then maybe there's a dodgy switch somewhere) Yes alternator is working, and I should have full power to the lighter, now whether it's a dodgy earth or live I don't know.

Also the mirrors don't seem to work, could it be related (late Chim, mirror relay is NOT in the drivers door) and the indicator lights on the dash are very dim (can't see in daylight dim) probably earth again, but I can't see how that could have such a dramtic current drain effect

[craigalsop]

Are you *sure* your battery is OK? Even new ones can die - what voltage do you get across it if you test the battery with a multimeter?

[qube]

incorrigible said: Pretty sure the drain isn't round the front of the car, all the power down there needs to be switched on (but then maybe there's a dodgy switch somewhere) Yes alternator is working, and I should have full power to the lighter, now whether it's a dodgy earth or live I don't know.

Also the mirrors don't seem to work, could it be related (late Chim, mirror relay is NOT in the drivers door) and the indicator lights on the dash are very dim (can't see in daylight dim) probably earth again, but I can't see how that could have such a dramtic current drain effect

Whether this will help or not try pulling one fuse out at a time, recheck if the ciggie and dash regain the volts, hopefully you might be able to locate the problem. I've read somewhere that if the wrong fuel pump relay is used the relay stays on and drains the battery, check to see if one clicks when putting the ignition on, if not it could be faulty. Check the other relays as well through elimination.

Are the battery terminals loose ?.

Good luck

[incorrigible]

craigalsop said: Are you *sure* your battery is OK? Even new ones can die - what voltage do you get across it if you test the battery with a multimeter?

Unless there's an intermittent fault with the battery, then yes, I'm sure, 12 and a bit volts, 13.5 up to 14 when the engines running

The trouble is, it'll work fine for a fortnight, long journeys, short journeys etc then I'll leave it for a few days come back and nothing. Start it on a start-charger, drive it round the block and expect it not to work the next morning and it'll fire into life (drive it all week, up to VW last weekend, a couple of trips to work last week and this morning Nothing)

So apart from "are you sure the battery is connected" and "Have you checked the fuses" has anyone got any suggestions of where I should start taking it to bits

[simpo one]

'I'll leave it for a few days come back and nothing. Start it on a start-charger, drive it round the block and expect it not to work the next morning and it'll fire into life'

Are you saying that it will work after 24 hours but not after a few days? That has to be either a drain somewhere (as you suspect) or simply that the battery can't hold a charge. Once a battery is like that, it will start fine just after charging, but be flat as a a pancake an hour later. I know, it happened to me!

I know this doesn't answer the question, but don't assume your battery is 'innocent' just because it starts the car after a charge.

[Smuggling Sam]

Had a similar problem myself with an occasional flat battery, I diagnosed it as the stereo. It is a face off model and if left in place for any length of time...flat battery. I have had numerous breakdown people tell me that it couldn't possibly be this but you tend to find out yourself through coincidence and luck.

[HarryW]

A quick way to check if it's being drained by something thats 'stuck on' is to disconnect the battery -ve lead, if it draws a small arch then something is still drawing current . Pull the fuses one by one until it doesn't spark?

If this seems a bit crude then (and ONLY if you have the basic understanding of electrics) put a Multimeter set to measure the current draw between the earth lead and the battery -ve terminal (ie in series), BUT ensure that you do not swich anything on whilst doing this as most home type portable multimeters do not take very large currents (nor do their leads).
Obviously all IMHO and takes no account of what type of imobiliser/alarm you have fitted and what it does with the key removed .

Harry

PS I must stress only put the multimeter in series with the batt if you are sure what you are doing, sorry to bang on if you're happy with this though

[incorrigible]

Been in the fg garage all fg evening, got absolutely fg nowhere, can't get the fg dash top off, can't get the fg lights aligned properly, fg door glass won't behave, fg stereo's got a mind of it's own, fg wing mirrors think I want to see low flying fg aircraft

Now sat down with a guitar and a fg nice bottle of "Rococo, Primitivo del Tarantino"

Have another go tomorrow

[ribol]

Question - why did you change the Alternator and the Battery in the first place, was it to cure the same problem?

The first thing I would do is disconnect one terminal of the battery when you park the car up (yes, I know pain in the arse), then reconnect next time you go to use a car. If this gets rid of the problem it is almost certainly a car problem, if it does not it is almost certainly a battery problem. Measuring the voltage on the battery is not much use in most cases, you can have the right voltage but not enough amps to start a car.

If you establish it is a car problem and there is definitely a “drain” then you need to isolate the circuit that is causing it. Then one by one disconnect things on that circuit until you find the problem.

The three most common faults I have found on cars in general over the years that do this are cigarette lighters that are on permanent supply (as TVR use), people think if they take the top bit out there cannot be a short there – wrong. If you have 6v at the cigarette lighter then you should have the same at the battery or a problem in that area.
If the rectifier is going down in the alternator it can charge when engine running and drain when not running, the warning light will not show this.
If someone has wired up an amp to shake the car with and does not know what they are doing!

Good luck,

Ivan

[shpub]

HarryW said: A quick way to check if it's being drained by something thats 'stuck on' is to disconnect the battery -ve lead, if it draws a small arch then something is still drawing current . Pull the fuses one by one until it doesn't spark?

If this seems a bit crude then (and ONLY if you have the basic understanding of electrics) put a Multimeter set to measure the current draw between the earth lead and the battery -ve terminal (ie in series), BUT ensure that you do not swich anything on whilst doing this as most home type portable multimeters do not take very large currents (nor do their leads).
Obviously all IMHO and takes no account of what type of imobiliser/alarm you have fitted and what it does with the key removed .

Harry

PS I must stress only put the multimeter in series with the batt if you are sure what you are doing, sorry to bang on if you're happy with this though

Harry... hate to say this but

Your suggestion with the battery is even worse and could lead to a dead ECU or other components inthe system. Electronics do not like arcs. It often turns them into useless bits of crud. The arcing is often caused by bits of electronics resetting themselves so is no real indication of what is going on. If you pull out the ECU or alarm fuses and the arcing stops all that tells you is that you have stopped the arcing.


Steve

[HarryW]

Point taken steve :0, feel free to ignore the dangerous advice re the disconnecting and reconnecting.
I was just trying to see if the current drain can be isolated, which with the proper use of a multimeter can be done, however this may not be the forum for that.

Harry

[incorrigible]

Ribol / Ivan, I haven't changed the alternator, how do you check a recifier circuit ? The battery was changed because the car was off the road for 16 months (see profile)

I've found Trefors site on how to get the dash top off, excellent, thanks.

So where is the earth for the indicator and high beam dash lights because they're different for the dash illumination lights, and is this connected in any way to the radio (because that's turned itself off once or twice on a long journey)

[ribol]

The easiest way to check if the Alternator is the source of your agro is to disconnect it when you park the car up(not at Tescos ). Once you have established the Alt is your problem it will be a waste of time trying to repair it and you may as well get an exchange one.

Ivan

[shpub]

So where is the earth for the indicator and high beam dash lights because they're different for the dash illumination lights, and is this connected in any way to the radio (because that's turned itself off once or twice on a long journey)

The dash earths are from the loom. The earth for the indicators, headlamps etc is under the radiator on the passenger side. It is the bolt that sits under the rad that holds the body into the chassis. Can be virtually impossible to get to. A very long thin extension bar might reach from the front. Others have moved/lifted the rad to get to it and someone cut a hole in the GRP to get access.

Steve
www.tvrbooks.co.uk

[incorrigible]

So are the "indicator DASH" lights and the dash illumination meant to be on the same earth ? Because they don't seem to be on mine

Front earth is fine, indicators and headlights work fine, they're just pointing in the wrong direction, but that's another story

[incorrigible]

Just to keep everyone updated......

Got the daash top off, 7th dan arm bendyness required (couldn't have done it without Trefor's help, tavrymuch) only to find that my suspicion of the dodgy earth was completely unfounded and the small piece of PCB that hold on the dash warning lights had come away (lights working perfectly but hence dim indicator repeators and light leakage to the main beam etc) all now glued back in, partial success...

Now getting 12 volts at the fag lighter (which I need seeing as I've gone from one marboro light every other week to 20 full strength camels a day since I satrted trying to fix this) can't trace the current drain

Still, managed to neck 3 pint of Stella in 30 minutes (got to the pub at 10:50) so I'm switching between calming down and wanting a fight every 20 seconds.

Hopefully be better at the motor show tomorrow