I have a '76 Comet six cylinder. The alternator is a rebuild of unknown pedigree (it was on the car when we bought it) I had it tested at the local parts store and it passed. New battery from NAPA. After market voltmeter (albeit an inexpensive one) still reads only 11 volts. A hand held voltmeter placed across the battery posts at idle also reads low. Before I throw a new alternator at this car what else could be the problem?
Not 100% about '76, but if it is external, it will be mounted on the firewall between the battery and shock tower. Here is some info & diag procedures on it: http://1bad6t.com/Maverick/repair/regulatortest.html You also have some fuse links in play, check the info here: http://1bad6t.com/Maverick/repair/engine_repair_02.html
Thanks, this is all good information. There is a regulator on the wiring diagram I have but I'll have to go out to the garage and see where it is on the car. I'm sure there's nothing like a traditional looking regulator but there is a strange flat gray box that I'm not sure of.
Yep, I got one. I thought most alternators were internally regulated so call me surprised. Thanks for the tips.
The Voltage regulator would not have anything to do with it. Its job is to prevent the alternator from over-charging the battery. Your alternator is obviously not putting out enough voltage. It should be around 14 volts.
Ford didn't mfg any internal regulator alternators until the mid '80s... Regulators can cause low voltage(especially the mechanical type) but generally low output is problem inside the alt... The 11v is a bit suspect, if that's all it's charging the battery should be too weak to start it... I'd manually charge the battery before doing anything to see if it will come up to 12v...
I seen the electronic style regulators not getting excited until the engine rev's 3000+ rpms. I went through 3 of them to find one that will work correctly at fast idle
At 11v the alt isn't charging, you are reading battery voltage which indicates it's discharged... If it's starting OK then your meter or connections are in question...
Does the voltage go up with rpm's? Or are you only testing at idle? Do you have stock pulleys or under drive pulleys?
Even at idle, voltage should be more than 11v. Unlikely he has under drive pulleys on a 6 cyl. I wud ck all my cables for resistance and make sure there is gud contact at all connections; seeing as the alt. is supposedly working properly.
Here's an update. I took the alternator to a local NAPA store that I trust and they put it on their machine. It put out 13.6 volts. As a control they took a new one out of the box and it was putting out 13.3 volts. I've replaced the regulator with a new one and the connector was in pretty bad shape so I replaced that. So, here's where I'm at; alternator testing good, new regulator, new connector with new wiring and good, clean connections. The result? I'm still only seeing 11 volts on the gauge, (drops to 10 when I pull on the headlights). I placed a hand held meter between the battery side of solenoid to ground and only got 11 volts. I'm stumped.
Is the alternator light on??? If so it's probably not charging at all so you are reading battery voltage... At this point you most likely have a wiring issue, need to verify all the connections... Here's a '77 diagram should be same as '76, I'd be checking the black/orange fuse link connected to batt terminal of alt...
