My 77 Mav's alt light is on. I just installed new gauges, alternator,and voltage regulator. When the car is running the meter is only reading 12v and I think it should be 13 or 14. I had the alt checked just in case it was bad, but it was good. I connected all the wires back and the only on that didnt have a wire was the ground. Does anyone have pics of an alternator hookup 77 with a 250
Make sure you look at whether you have a LOW MOUNT or HIGH MOUNT style from the picture below. Sounds like your Alternator is still bad, but a number of things could cause this. One thing's for sure...your alt light is coming on because your voltage is only reading 12v with the engine running, instead of 14 or higher. Make sure you also don't have a BAD battery. Check this stuff, and post back and tell us if all of this is good. - Roger
i would be more suspicious of a faulty voltage regulator, I have bought new ones more than once that were bad.
Still on Ok I replaced the regulator twice, had the alternator checked twice, and I went ahead and put in a brand new battery. The light is still on. I reomoved the positive cable while the car was running and it died. I was also wondering if i could have the wire hooked up wrong on the solenoid. Does anyone know where it hooks up to on the solenoid? Thanks
Okay. Quick Tests: 1. With everything connected up and your engine running, use a voltmeter or multimeter, and put the leads across your battery, and put the meter on the AC setting. You should measure less than .5 volts AC (500 mv AC) across the battery, if your diodes are good in the alternator, with the engine running. 2. This may sound silly, but make sure that your belt is turning the alternator. (be careful when doing this). more explaination: Your alternator light is controlled partially by the DIODE TRIO inside the alternator. An alternator also has 6 other diodes that are used to rectify the 3 phases of AC (Alternating Current) in the stator, and convert them to DC (Direct Current), for your car to run on its DC electrical system. The DIODE TRIO is what allows an alternator to "run the car's engine", if a battery is disconnected after the engine is started. However, it is not a good idea to disconnect the battery while the engine is running. The DIODE TRIO feeds current generated from the alternator, back into the rotor, for field current, to help charge the battery, and energize the coil. If only one of the three diodes in the trio are bad, an alternator will "work", but act "weak" and charge at a lower voltage. If all 3 phases of your alternator's windings were not tested with a good tester...watch out... it may have tested "good" with a cheap tester. Sometimes disconnecting a car's battery, while the engine is running, can damage the diodes inside of the alternator, as well as damage other electronic components in the car's electrical system. If your DIODE TRIO, and alternator output rectifying diodes are good, you should have less than .5 volts AC across the battery, when the engine is running. You should also have around 14 volts DC, or higher across the battery when the engine is running. You already said that you only have 12 volts DC when the engine is running, which is also a sign that the alternator has a bad diode. If the voltage regulator is bad, it can cause the voltage to be 15 volts DC, or higher across the battery, when the engine is running. Try the quick test above, and let us know what it reads. I also pasted a partial picture of the charging circuit for a 77 Maverick, so that you can double check your wiring to the solenoid, and other component. I labeled some of the components that were not identified in the original drawing. Good luck. - Roger
Checked with meter I checked the battery with the car running and the meter set to V AC. I got a reading of 22.8. Just be sure I did it right I did the same thing on my 99 Chrysler which I know is working properly and I got a reading of 29.8. So I think I did it right. I used a test light on my fusible link and nothing. So I think my link needs to be replaced. So next question how do u replace a link and where do you get one from?
I think you're talking about the fusible link wire, which is color-coded depending on the over-current protection rating (in AMPS). There are fusible links that look like regular fuses too. Fusible link wire is usually "fused" on a portion of one end of the wire. If it is bad, you should replace the whole fusible link wire. You should be able to get fusible link wire at most local auto parts stores. You can also find it on Amazon. Make sure you get the correct size that matches the one you replace.
