I have a 2ltr 626. I stupidly crossed the wires recently when jump starting it.
The car seemed to start and turn over okay but when I took it out for a run the rev counter, lights, etc all flicked from low to high. I assumed that the alternator rectifier was damaged.
I took the car to my local garage to have a second hand alternator fitted, which they did and it solved that problem. However the car is now overcharging, I assumed that the voltage regulator on the replacement alternator was faultly.
However the garage (after six weeks investigation) have told me that the alternator is fine and that the fault lies with some sort of control box in behind the dash. As they are unable to source a wiring diagram, they can't tell me what the control box is for.
I am planning to replace the alternator with a recon/tested or new unit, to see if it makes any difference.
Any other ideas?
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Any other ideas?
yes.
get a third party to check the alternator output voltage under load
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H
As bb says; far too many assumptions and few hard facts. Rectifier damage will normally put the battery light on; [if the bulb survived.]
What year and engine is this 626? What is the overcharge voltage of this new alternator? Where exactly is this mysterious box? Does the car have dim-dip headlights?
Reversing polarity only works on starships; on mundane things like cars, all sorts of electronics get damaged.
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I pick the car back up this week and will check warning lights and voltages, the guy at the garage mentioned that it was 14v rather than 12v but I've not checked this myself.
When I said that the lights went high and low I meant that the dash lights were flickering, which I took to mean that the power was troughing and peaking.
I'll have a word with Scotty.
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H
Err; 14v is the correct charging voltage..... Maybe you need an auto-sparks....
[Scotty was last seen "outbound" - not sure if he's back yet....]
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I'll check all this when I get the car home. So that I know what I'm looking for, what voltage should I expect across the battery under the following conditions:
Engine off
Engine idling
Engine idling under load (rear windscreen, headlights, etc.)
Sorry, I don't know much about electrics auto or otherwise.
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Another factor that just occured to me. Does the voltage across the battery change depending on how much charge it currently holds. i.e. if the battery is almost flat would the alternator put a higher voltage across the battery?
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when the engine is off expect to see around 12volts (mine is 12.48v) - when the engine is running you should see around 14 volts (mine shows 14.44v). When headlights, wipers etc are switched on with the engine running you may see the voltage drop momentarily but if the alternator is ok then it should go back to 14v again quite quickly. A flat battery will draw more current than a full one but the voltage will be the same.
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H
Engine off; absolutely everything off; [or earth lead off] - after 2 hours stabilization time.
12.6v and above - fully charged.
12.3 - 12.5v - half charged.
12.2v and below - flat
10.5v and below - susp. dead cell or parasitic drain.
At 1500 revs - no load 14-14.4v.
At 1500 revs - only heater fan; HRW; headlights on - 13.5v minimum.
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The 626 is actually my second car, my first is a 2ltr Vectra. I borrowed a mutimeter and checked the Vectra battery to see if I could get my results to match the above. With a cold engine I got 12.38v and with it running I got 14.25v (no load).
I picked up the mazda last night from the garage and they jumped it from a booster pack before I could take a reading from cold, however it was reading at 15.4v running with no load. I ran it home (10-15 mins) and checked it again before switching it off, 15.15v.
At the moment I suspect the battery (it's been garaged since May and is pretty dead), so I am going to try checking the voltage of the battery from cold and if it's really low then I'll try swappping the Mazda battery with the Vectra one and see what voltages I get, that should allow me to determine whether the problem is the battery or the car.
If the Mazda still runs at over 15v, am I likely to cook the battery and what other components might I be putting at risk?
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I'm getting a little tired of working blind here. How about answering the question about the year?
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Sorry, it's a V reg (2000)
{Added to subject header - DD}
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The battery has been flat for quite a while now, so I bought a battery charger to see if a fully charged battery would be work better.
I checked the charge on it before charging and it was 12.17v, once I had finshed charging it I left it to stand overnight and when I checked it in the morning, it was 12.53v
I put it in the Mazda and it had enough charge to turn the engine over a couple of times but not enough to start it. I then put the booster pack on it and it started. However the battery then measured less than 12v, which is odd with the engine running, I looked in the car and the battery warning light was on. My assumption was that I'd damaged the battery trying to charge it.
I put a new battery in today, I measured the charge first, which was 12.59v. Got in the car and turned the key, the car started after a couple turns. I sat for a minute watching for the battery warning light, when it didn't come on I got out and measured the voltage across the battery, it read 12.06v which is odd, as I expected it to be higher than the inital full charge value.
I looked back in the car and the battery warning light was back on. I let the car run for a couple of minutes but there was no change, so I switched it off. I then checked the battery and it was reading 12.36v (half charge). So obviously the car was running off the power in the battery and the alternator wasn't charging.
It seems to me that the alternator is goosed but the battery warning light didn't come on when I was driving the car home from the garage so why now?
Any ideas?
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H
It's clearly not charging; don't confuse yourself with the changing voltages - remember that a voltmeter can only assess a battery's state of charge AFTER TWO HOURS standing disconnected. Anything measured sooner is meaningless.
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I took the old alternator off and had it tested. I was told that the Voltage Regulator and Diodes needed replaced. My assuption is that it was overcharging due to the faulty voltage regulator, which in turn burnt out the diodes.
Bought a second hand replacement with warranty. Fitted it and the car now charges normally. Won't be using that garage again or recommending it. If this fault had been properly diagnosed by his "Auto Sparky" then I could have exchanged the faulty unit under warranty.
As it is he had the car for six weeks before handing it back saying he couldn't fix it because his Auto Sparky couldn't get wiring diagrams from Mazda.
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