Technical 2.0 20v not charging

[41northpole]

Hello all
Interesting forum, I am new here so I hope you may be able to help me.

I have a Marea 2.0 20v. 2 days ago the battery charge light came on. Investigating this I found that the field coil connector on the alternator is being fed only with 1.04v with the engine running. This should be fed at around battery voltage to energise the alternator. If I connect 12v to this connector from the battery, the dash light goes out and battery voltage increases as the alternator is now charging.
My question is this, I cannot find the voltage regulator pack in the engine bay, does anyone have detail on where this is , or how the field voltage is controlled. Circuit diagram would be nice if anyone has it.

Many thanks fro and help you can provide

 

[polecat]

Hi and welcome to our forum.

Best I can make out is that the reg is in the alternator along with the rectifier. The only other connection on the diagram is the o/p to the indication.

 

[ebme2]

Most of the Fiat's I have had the rectifier and regulator packs built into the alternator as polecat metioned, quite often as a replaceable pack on the end of the alternator, some integrated within the brush holder . The output you mention is just for driving the lamp, it can also supply the power to drive the regulator circuitry within the alternator which may be why when you connect 12V all works again. I would suggest the rectifier/regulator has gone, some alternator repair centres have the facilities for testing, and you can normally buy the unit, but need to way up cost and inconvenience against service exchange alternator.

Hope this helps

 

[41northpole]

Hi Guys,
Thanks for the details, I got the alternator off the car (nasty job) and stripped it. I found that the internal wiring between the regulator output and the rotor brushes was corroded ( fell to bits as I looked at it) I have replaced this with a piece of wire external to the 'potted' circuit beneath the regulator. All now works, but it's quite a job to get everything else off first to reach the alternator ( radiator and A/C pump).
When I first posted, I thought the small wire into the back of the alternator was the field supply, which is why I was confusing myself over putting 12v on this and still getting no charge, but the light went off!
Amazingly, having done this job on one car, 2 weeks later our other Marea also did the same (great bank holiday monday, that was).
Luckily we don't have a third one!!