Originally posted by brianl703:
At idle, that 130 amp altenator is capable of putting out 80 amps @ 13.5 volts or so (the output voltage will drop as the voltage regulator heats up, but never below about 13V).

It shouldn't be dropping as low as you are reporting. No way, no how. At 12.2V, you are discharging the battery. At 11.8V you are discharging it even more. Not good.

It's normal for the voltage to drop that low with all of the accessories on at idle in a 1988 Mustang GT with a 65-amp alternator[which, in fact, is why I replaced with a 130-amp alternator], but it is NOT normal for any Contour.

If I had to take a guess I'd say that one of the alternator diodes has gone bad. That usually causes diminished alternator output, with the possible side-effect of causing a battery drain when the engine is off.



Originally posted by stepmar2:
Money,

The nominal range with all accessories on is 13.2-14.2V. If you are reading 11.8-12.2V your battery is not getting charged. You probobly already know that though. What you probobly didn't know is that you ground and positive cables could be at fault and that is about a 50% chance roughly. Check the integrity of those first as well as the mega fuse which is located near the firewall on the back of the wiring harness central section right under the ignition module on Duratec 2.5L. If those both look and test fine then proceed with alternator removal and get it tested before you buy it. If at all possible, remove the voltage regulator and check the brushes for dirt, oil, dust, and corrosion. You may be able to check out cheap without having to buy a complete unit. Voltage regulator is $30 compared to $130 at Auto Zone.
If you do all this and still have no luck, check your wiring harness. Those aren't cheap from Ford either..
IDEA.. find one used and test it first if needed!



Thanks, exactly the kind of info I was looking for!

-- 1999 SVT #220 -- In retrospect, it was all downhill from here. RIP, CEG.