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Discussion Starter #1
my battery was down to 3v from 11 last night so, i noticed that when i hooked a new battery up today that when i put the earth on it sparks a wee bit like there is a draw on it.

on the +ve side there is literaly about 6 constants(inc main loom feed and ecu feed) coming off the battery so i began removing one at a time to see if the earth stopped sparking when i put it on. it did.

with every one connected bar the thick red that goes into the main car loom it never sparked. as soon as i connect that main feed back to the +ve side it starts sparking at the earth when i connect it.

so with the meter set on Ohms, i measured the resistance between earth and the main loom feed and the resistance was nil.

now am i right in thinking this is a short circuit then?

i have the loom traced and im at the back of the digidash with it where the thick wire splits to a few thinner ones, some diappearing into the loom again and some to fuse box.

any ideas what the best way to check each one for shorting is? will i have to cut them all free and test each individually?

cheers

rodgerq
 

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wouldnt stuff permenantly connected to +12v be returning your test signal, or completing the circuit. stuff like the clock, alarms etc.
 

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If the resistance was Nil you'd get a nice big boom as everything melted ;)

Stick the meter on its 10 amp setting if its got one and put it in series (between) the wire you want to test and the battery. The reading will go high for up to a minute then should die down to a maximum of about 0.1 amp.
 

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Did you disconnect all positive feeds and measure the resistance of just the thick red lead to earth? Does the car turn over on the key?
 

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dosent sound like a short circuit, you would have a fire and big sparks if this was the case... switch the multimeter to amps and put it on the biggest range (around 20A should do) and put it between the earth and the -ve terminal. this will tell you the current draw.
do you have an alarm / central locking? was the door open when you connected it?
 

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Do as dom said, set the meter to 10 amps (might need to change the leads around) and connect between the battery positive and the main feed. Make sure everything is switched off, even the interior light, otherwise you'll get the wrong reading and may damage your meter. If the car has an alarm it's a good idea to do this test while it's armed.
 

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Discussion Starter #8
my meter doesnt measure amps tbh. its an engine analyser meter with voltage, ohms, dwell and some other stuff but no amp measuring.

heres what i did. the thick red wire was branchin off at the back of the digidash with about 7 branches coming off it. when i connected the meter(in ohms setting) to the crimped connection where the branches come off and to earth(earth cable, battery disconnected) the reading on the meter was zero 0000.

so i began cutting each branch till the meter reading indicated a high resistance. when i cut the power lead goin to the fuse for the hazzards this happened. i checked every other branch seperate and they all read a high resistance except this one which read zero ohms from earth to it. so i traced it down to the fuse and pulled the fuse, meter jumps up.

so i have now reconnected everything and reinstalled the digidash but ive left that fuse out just now.

what are poeples opinions of this?

rodgerq
 

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Discussion Starter #9
oh and im gettin code 48 - alternator voltage too low even though it reads 14v on the meter. ill d/c the battery and clear it and see if it reappears.

the car is now starting and running for a while(varied times) and then starts to get a bit rough then eventually cuts out still.

rodgerq
 

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It won't be a full short circuit so I don't understand why your meters reading zero?? If it was a full short, you'd have been getting a massive spark when you connected the battery, and the hazard fuse would have blown instantly.

Is it a digital or analogue meter?

You really need a meter that can read at least 10 amps. Then you can see exactly how much current is being drawn from your battery, and if removing the fuse stops it. You can get one for less than a tenner from maplins i think.
 

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Discussion Starter #11
its a digi meter. i will try and get hold of a meter that can read amps. ill get my burd to pick me one up the day.

i cleared the fault code 48 for low alternator output and its came back again even though im gettin a constant 14v from the meter.

i notice aswell that the digidash and check lights are lighlty flickering, nothing major but if you watch it you can see it happening.

AND lmao

when i put the lights on the digidash lights go out :confused:

rodgerq
 

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Discussion Starter #12
richie00boy said:
Did you disconnect all positive feeds and measure the resistance of just the thick red lead to earth? Does the car turn over on the key?
yes and this is where i got a zero ohms reading. it turns and starts on the key

i am surprised to that nothing has melted including the whole fuse box TBH as that thick red wire is the main loom feed.

rodgerq
 

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Discussion Starter #13
i will take a picture of the meter readin zero while connected to the wire to show people who are dubious, lol

rodgerq
 

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Discussion Starter #14
ok so NOW the meter isnt readin zero BUT IT WAS. i aint stupid i do know how to use a meter, lol. im just wondering whether me moving the wiring about has ceased the short.

the car now starts but doesnt idle well and misses sometimes and sometimes cuts out aswell. gony do the icv to eliminate that.

still gettin the 48 code even though its charging fine

rodgerq
 

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sorry to say this mate but if you need a lift to the rolling road day let me know..... seriously this car has been nothing but bad luck for you. I take it this is a new alternator you are using.
 

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Discussion Starter #16
tell me about it Alan. its unbelievable really.

rodgerq
 

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Hi rodger, have you put a new alternator on this car?

If you have i take it youve stripped the power steering off and used a V belt pulley and alternator!

If you have done this make sure your new alternators main feed (ie big red) is insulated from the alternators casing.You can do this by cutting a square of plastic and drilling an 8mm hole in it.

After you have put this on the case of the alternator then tightened down your 8mm nut you should not be getting a spark from the earth lead. (should you not get a slight spark when sticking either the earth or the live on the battery anways :confused: )
 

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Discussion Starter #18
Andy, ive had 3 alternators on it mate. still no joy.

wont be tryin anythin for a good while now as we used the lambda today in the nova and had to cut it out of the elbow at about half 6 lmao

rodgerq
 
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