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alex park

1997 D1 v8. battery discharging in 8 hrs

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If it's any help. I have a 300Tdi that runs flat when parked up but charges Ok when running, I have had it confirmed that the alternator is draining the battery when not running. (there is also a slight noise from the alternator when parked). Spares not available for my alternator (Magneti Marelli) so presently searching for cheap replacement.

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well i bought an new battery for £100 and it did the trick, i guess i should have listened to the posts at the beginning of this thread.

Started like a dream, roared into life.

the only minor niggle i have now is that when i turn the ignition on. the "check engine" light flicks on then straight off.

it never did this before.

theres no other problems with the engine it starts and drives fine, but just one of those niggly things.

perhaps i should do a homer simpson and put a bit of black tape over where the light is ha ha.

any suggestions?

thanks for all the advice previously.

Alex

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The "Check Engine Lamp" is supposed to flash on during the ECU initiation sequence, standard for a 14CUX ECU. It is used as a lamp check.

jw

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flat again this mroning, so i guess my being premature was, well premature.

gonna check the alternator this mornign and see if i can find the culprit.

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if the alternator is discharging the battery when it is at rest, does this mean that i need a new alternator?

which on of the three wires is the actual charge wire.

on the back there looks to be three wires bolted to the alternaotr plus a small wire connected to blade fitting.

Alex

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left the charge wire off the alternator overnight and it seems that the battery went flat anyway.

so i think that will discount the alternator "back charging"

can anyone tell me where the earth straps would be so i can check those please

alex

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You should be able to see the earth straps, they're the big hefty wire going from the chassis to the battery and the starter to the chassis, the one from the battery goes straight down to the chassis, a good way to rule out a bad earth strap is to run a jump cable from the battery to the engine block.

I don't think it will be the earth though.

If anything is drawing current from your battery it will show up with an ammeter as suggested already.

But as the others said the "1" showing on the screen should mean it's off the scale.

When you disconnect and reconnect the positive terminal does the lead spark? If it does then something is draining quite a bit of power, if it doesn't then it could still be a bit of a drain. Be careful making sparks as batteries can give off explosive gases though.

Also try the advice above and connect a bulb up between the battery and one of the leads

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Not sure how the earth straps could effect a discharge?

Anyway as your problem is a little complicated you may need a different approach.

As I understand it now, the battery will flatten, without fail, if left overnight yes?

If so, get a circuit diagram from Haynes or Rave and pull fuses for half the circuits on the car that are permanently live

If it's flat in the morning you know it's a circuit on the other half

If it's ok then you've pulled the fuse on the bad circuit

Next night pull half of the fuses in the previously found bad half (IYSWIM)

and repeat until one night you pull one of two fuses and Robert's you Dad's brother

My first half to pull would include the ECU, alarm, stereo, interior lights

Have you got a grey trailer socket fitted?

HTH

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positive battery lerad does spark when i disconnect or reconnect it, so as you say it points to a big drain hence the mm showing the 1.

i will go along the route of the half fuses and see what that brings.

thanks for all your help guy and sotal.

be lost without it.

Alex

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No worries,

if you're getting an obvious spark then something is definatley drawing power.

I'd connect the ammeter up as said above so you're getting a 1 on the screen then pull the fuses one by one until it drops - that should give you an answer quicker.

Let us know what fuse sorts it

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My only reservation about the ammeter is that when the sidelights were switched on it read 9.4A (higher than I would have expected - would have expected more like 3A or 4A) and when switched off went back to 1.

Either when the lights are off there is more current being drawn (remotely possible I suppose) or the meter involved reads 1 when the current is less than a set amount.

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Hmmm....I expect that the act of turning on the lights is introducing some extra resistance into the circuit at fault and therefore generating a lower reading...somehow. Treat the 9.4 as if it is still off the scale - the point is that you still have the drain, therefore you haven't yet pulled the correct fuse.

Connect up the multimeter, leave everything off (drain present, so multimeter reading 1___). Pull one fuse at a time until you see the drain disappear - that will be your fault circuit. Once you have isolated it, trace wiring and components to try and pinpoint it. It is a nobflattening job, but better to find it than randomly grasp at straws hoping that you guess right.

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My only reservation about the ammeter is that when the sidelights were switched on it read 9.4A (higher than I would have expected - would have expected more like 3A or 4A) and when switched off went back to 1.

Either when the lights are off there is more current being drawn (remotely possible I suppose) or the meter involved reads 1 when the current is less than a set amount.

I thought the same as Guy - it might be that it's less than it can show with that particular multimeter, in which case you can measure using the non 10A socket but will blow the internal fuse if it's more. It depends how big the spark is, if it's quite a big spark when you reconnect then it's a big draw.

Good luck and let us know how you get on.

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ok connected ammeter up inline as advised during the thread. meter reading 1.

pulled all fuses from main fuse box, satalite box b and satalite box c.plus the ones in the engine bay

there was no change to reading it kept a constant 1.

i checked the voltage across the fuses with everything off.

the following showed 12v+

all satallite b which are

electric windows front/rear

anti lock brakes

central locking

sunroof

trailer lights ( i do have tralier tow hitch and electrics fitted)

in main fuse box

rear fog light

multi function unit

in satallite c

anti theft alarm (fuse 1 and 5)

rear air con/heater

are these the ones which are supposed to be permanently live?

are there some circuits that are not fused?

thanks

Alex

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The fuses are fine to be live with everything off. With all fuses pulled out do you get still get a spark when you reconnect the battery lead?

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no there is no spark at the pos terminal when all the fuses are out

put them back one by one until you get a spark

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If the meter is just reading a plain 1, rather than 0.01, 0.1, 1.0 etc, its most likely out of range, and not giving an actual reading at all, as has been said previously.

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ok the very first fuse i put back in was the trailer lights fuse (fuse 6 satallite 2)

this made the terminal spark.

i removed this and replaced the others one by one checking each one to see if it also made the terminal spark.

the rest never.

so the trailer lights fuse was the only one to do this.

i have removed this.

what is the significance of this "sparking" caused it seems by the trailer lights wiring?

excuse my ignorance, like i say mechanically i dont mind fiddling around but the electrics bit scares the pants off me.

also earlier GUY H asked if i had trailer lights fitted, was this because its a common fault?

alex

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Sounds like you've found the fault, with this removed does the main terminal lead now spark when you reconnect the battery?

Leave that fuse disconnected and see if it goes flat or not, but it looks like you found the culprit

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no it doesnt spark anymore with the offending fuse removed.

I'll leave it removed and see if the bater flattens as you have suggested.

Looks like we may be getting somewhere.

many thanks, indisspensable info

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If it no longer sparks then it certainly looks like you've found the offending circuit.

Do you use the tow bar at all?

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