Alternator Issues

[happygoron 2]

Continuing from this thread as my problem has changed somewhat and I don't want to take it off topic. Here's the full story:

 

• Last week the car broke down with no electricity. Battery light had been on intermittently due to what I thought was a slipping belt and I pushed my luck about 6 miles too far! RAC diagnosed a duff alternator and pumped the battery up so I could get home.
  
• Old alternator (not a 205 one, higer amp off a 306/405 etc.) was removed and replaced with a recon standard gti item.
  
• Wiring was altered to fit from the two ring connectors on the old alternator to the new ring connectors on the new one with the brown wire attached to the B- terminal and the red live wire attached to the B+. Battery was recharged and car was started but battery light was on.
  
• From this thread I determined that the brown wire should actually go onto the spade connector on the alternator, so I swapped this and car started with battery light out. However a multimeter across the battery terminals read 12.3V whether the car was running or not, even when it was revved.
  
• Took car for test drive and saw that turning on the headlights dimmed the clock etc. She ran out of battery power again after about 15 miles.
  
• Battery has now been removed and tested with a multimeter and was reading 12.4V, put on a mains charger and then read 12.6V so must be charging again.
  

After all this I have 3 questions:

 

• Have I wired the alternator up right? Thin brown wire is attached to the spade connector on the alternator, thick red wire (straight from battery +ve) is connected to the terminal on the alternator marked B+. There is nothing connected to the terminal on the alternator marked B-.
  
• If it is wired up right could it be a duff alternator? I didn't detect a voltage increase when the car was running, however the battery light did not come on at all during the last test drive either.
  
• The battery has had a lot of charge dumped into it by the RAC and being totally discharged at least twice now, could it be that this is just knackered?
  

Anyone have any ideas?

Many thanks,

Neil

[large 33]

If you can get your voltage readings off the back of the alternator. You should see about 14.4 volts with the engine running. Also check the continuity (spelling) between the alternator and the battery, it should be 0 ohms.

[steve@cornwall 100]

I notice in another thread you mention an accasionally sticky starter? May be worth cleaning up the main earths on the gearbox.

[happygoron 2]

Right, upon further multimeter checks we think the recon alternator is a duff one so changing it on monday when gsf get a replacement in. Fingers crossed we're right!

[happygoron 2]

Cheers for your help guys, looks like it was a dodgy alternaor. Just goes to show just because it looks shiney and new doesn't mean it'll work! Fitted a replacement today and getting 13.2V without the engine and 14.5V with. Gonna take her for a drive tommrow when I'm feeling better for a final test but happy with that! GSF service was good too, bar the fact that the first one I got didn't work!

Edited April 20, 2009 by happygoron

[happygoron 2]

Never that easy! The alternator does appear to be charging (though not initially after starting, need to rev it a little first). However the battery light on the dash doesn't come on at any point in the ignition sequance at all now, turning the key just lights the stop light in the central lights. Assume the bulb is ok as it was working a week ago (big assumption!). Any ideas?

[Tom Fenton 1,542]

BROWN MULTIPLUG OF DOOM!!!

[happygoron 2]

BROWN MULTIPLUG OF DOOM!!!

 

Way to make my puganoia worse! Does the brown spade connector go to the multiplug then up to the dash?

[ade 4wd 11]

Yes it does go through the brown connector in the engine bay.

[happygoron 2]

All sorted, cheers guys! Had to change the brown wire from the alternator spade to the "brown multiplug" (not a brown mutli for me, all the wires had been connected seperatly and taped up, took me fooking ages to find it as it was covered and looked like the rest of the bundle! Noticed the wire had a high resistance so changed it and now all seems well.

 

Till next time!