what's the easiest way to diagnose faulty alternater.
Moderator: martauto
hi, guys driving down the a13 tonight , the dash lights went dim , stereo went off, abs light came on , never done this before, obc went dim , headlights went dim, automatic gearbox light and window switches went off, but previously to this the battery kept going dead , put brand new 1 on , it last 2 days the dead again , it's so bloody annoying, do you think i have a bad earth? please help!!!!!!!
Last edited by e30geezer on Tue Nov 29, 2005 6:53 pm, edited 1 time in total.
mate, thanks gonna look at it tommorrow, hope this cures it. i know it's something stupid. let's see. cheers mate.koos wrote:Check the charge rate and the belts, see if it's charging probably. Check the earths like you say, and pos cables aswell.
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Brianmoooore
- E30 Zone Team Member
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Dud altenator. Regulator/brush pack is available seperately.
This belongs in tech. help, so moving it.
PLEASE POST IN THE CORRECT FORUM.
This belongs in tech. help, so moving it.
PLEASE POST IN THE CORRECT FORUM.
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Brianmoooore
- E30 Zone Team Member
- Posts: 49358
- Joined: Mon Jan 10, 2005 11:00 pm
Think you've already tested it when your new battery went flat in two days!e30geezer wrote:thanks mate, sorry, whats the best way to test it.Brianmoooore wrote:Dud altenator. Regulator/brush pack is available seperately.
This belongs in tech. help, so moving it.
PLEASE POST IN THE CORRECT FORUM.
Only cable connections that could be at fault are the ones at the ends of the thick red wire that goes from the altenator to the starter motor. All other relevent cables are common to the starter circuit, so you would know from other symtoms if these were at fault.
A long shot is corrosion between the altenator body and the engine block. Came across this once on a big agricultural tractor, where this was the problem, although all bolts were tight, had not been disturbed and looked clean.
Way to test the altenator is to run the engine at about 1500 RPM and measure the battery voltage. Should be between 14 and 15 volts.
Switch the headlamps on - voltage should dip slightly then return to the same.
Does your ignition lamp work? Altenator might not work if this circuit is faulty.
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Brianmoooore
- E30 Zone Team Member
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- Joined: Mon Jan 10, 2005 11:00 pm
About a year ago, a friend of mine, from about 200 miles away, pulled into my yard out of the blue, with a rapidly dying non BMW.
He wanted to phone the AA to fix it, but I had a quick look, said it was the altenator (brushes), and that I could fix it to last another 1000 miles in about 10 minutes. (By removing the regulator pack and stretching the brush retaining wires slightly).
My friend said he'd been paying the AA for bl**dy years, without getting a penny's worth back, and now that his car had broken down, he was bl**dy well going to make use of them, and would I put the kettle on.
Eventually the AA man turned up, and after watching him makes a right pig's ear of diagnosing the proplem, obtaining the part, and fitting it, I swore I'd never let an AA man near one of my cars.
He wanted to phone the AA to fix it, but I had a quick look, said it was the altenator (brushes), and that I could fix it to last another 1000 miles in about 10 minutes. (By removing the regulator pack and stretching the brush retaining wires slightly).
My friend said he'd been paying the AA for bl**dy years, without getting a penny's worth back, and now that his car had broken down, he was bl**dy well going to make use of them, and would I put the kettle on.
Eventually the AA man turned up, and after watching him makes a right pig's ear of diagnosing the proplem, obtaining the part, and fitting it, I swore I'd never let an AA man near one of my cars.
same here i dont let them near my cars , just ask em to put it on tow.Brianmoooore wrote:About a year ago, a friend of mine, from about 200 miles away, pulled into my yard out of the blue, with a rapidly dying non BMW.
He wanted to phone the AA to fix it, but I had a quick look, said it was the altenator (brushes), and that I could fix it to last another 1000 miles in about 10 minutes. (By removing the regulator pack and stretching the brush retaining wires slightly).
My friend said he'd been paying the AA for bl**dy years, without getting a penny's worth back, and now that his car had broken down, he was bl**dy well going to make use of them, and would I put the kettle on.
Eventually the AA man turned up, and after watching him makes a right pig's ear of diagnosing the proplem, obtaining the part, and fitting it, I swore I'd never let an AA man near one of my cars.
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Brianmoooore
- E30 Zone Team Member
- Posts: 49358
- Joined: Mon Jan 10, 2005 11:00 pm
And if it's not the altenator, it could well be the engine ECU, the ABS ECU, the alarm, the ICE, and any other electronics on the car after the power surge this will cause. DON'T DO IT.ady786 wrote:try and starting the car rev it to 2000rpm and take the battery leads off if it dyes out its the alternator
ditto definately dont disconnect when running lol 
sounds like alternator but before fitting at random do yourself a favour and buy a cheap multimeter and test charge output 14.5v ideally at around 1500 rpm as already pointed out.this will be a useful tool to you in the longterm !
sounds like alternator but before fitting at random do yourself a favour and buy a cheap multimeter and test charge output 14.5v ideally at around 1500 rpm as already pointed out.this will be a useful tool to you in the longterm !