I have a crazy problem, and in need of some serious help. My 71 Duster with a 340 isn't charging. The battery is at 12v even at the alt. Once I crank the motor up the alt is putting out like 11.3v. I have checked all the wiring and everything seems to check out. The only problem I see is my electronic ignition box. With the blue/yellow striped wire unplugged from the ballast it is reading 1.6v for some reason. Now while it is unplugged I 11.9-12.0v on the ballast resistor. Once I plug the blue/yellow stripped wire to the 12v feed on the ballast it drops to 9.8-10.1v. The alt will never charge when the field wires are at those low volts. Has anybody else ever had this problem? It has absolutly got me stumped.
Low voltage = no charging
- Thread starter Mr2.4
- Start date
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67Dart273
Well-Known Member
Explain what this blue/ yellow wire is that you are unplugging?
The "high" (battery) sided of your ballast, one of the field connections, and the IGN terminal of the regulator (blue) are all supplied from the "ignition run" contact in the igniton switch. First thing I'd do is make sure all three of those are "same as battery" or within .2V (two tenths) or so. More indicates a too much voltage drop. Your path is from the battery, to the starter relay stud, through the fuse link, through the bulkhead, to the ammeter, to the ign switch connector, through the switch, back through the bulkhead connector, and to the three feedpoints I mentioned above.
If these are OK, do a "quick check" on your alternator. Confirm that you have battery/ key on at the blue field connector. Unhook the GREEN connector, and run a clip lead to ground, from the exposed alternator field terminal with with the key on
You should see a spark as you hook/ unhook the clip lead.
Now start the car and gently give it some RPM while watching the ammeter/ voltmeter. The voltage / amperage should come up, you are operating the alternator at what is commonly called "full fielding."
If nothing happens, you probably have something wrong in the alternator. Make sure you have battery at the output stud, and check as above while running to see if you have (high) voltage at the output stud. If not, alternator problems.
If it DOES charge with the field connected, double check continuity of the GREEN wire back to the regulator.
With engine OFF, but key ON (run) check voltage at both connections inside the regulator plug. You should have "battery" at both. If you do, probably a bad regulator.
The "high" (battery) sided of your ballast, one of the field connections, and the IGN terminal of the regulator (blue) are all supplied from the "ignition run" contact in the igniton switch. First thing I'd do is make sure all three of those are "same as battery" or within .2V (two tenths) or so. More indicates a too much voltage drop. Your path is from the battery, to the starter relay stud, through the fuse link, through the bulkhead, to the ammeter, to the ign switch connector, through the switch, back through the bulkhead connector, and to the three feedpoints I mentioned above.
If these are OK, do a "quick check" on your alternator. Confirm that you have battery/ key on at the blue field connector. Unhook the GREEN connector, and run a clip lead to ground, from the exposed alternator field terminal with with the key on
You should see a spark as you hook/ unhook the clip lead.
Now start the car and gently give it some RPM while watching the ammeter/ voltmeter. The voltage / amperage should come up, you are operating the alternator at what is commonly called "full fielding."
If nothing happens, you probably have something wrong in the alternator. Make sure you have battery at the output stud, and check as above while running to see if you have (high) voltage at the output stud. If not, alternator problems.
If it DOES charge with the field connected, double check continuity of the GREEN wire back to the regulator.
With engine OFF, but key ON (run) check voltage at both connections inside the regulator plug. You should have "battery" at both. If you do, probably a bad regulator.
The blue/yellow stripped wire is the wire that is coming off of my mopar orange box. I put a electronic ignition on the car. It is carrying a low voltage and is dropping the voltage as soon as I hook it up.
fourspeed
Well-Known Member
12V at the alternator sounds like a bad alternator. Take it in to the auto parts store and have them test it.
slantsixdan
=..=
12v at the alternator doesn't necessarily point to the alternator being faulty. Remember, the voltage regulator is not a throttle valve placed in between the alternator and the battery. The alternator B+ (output) and the battery positive are electrically common. A faulty voltage regulator, faulty wiring or connections between the ignition switch and the voltage regulator, or faulty wiring or connections between the regulator and the alternator can all produce this symptom.
The system is really simple. Components are alternator, voltage regulator, ignition switch. Here's a diagram; your '71 car uses the electronic system shown on the right:
Check for line voltage at the blue wire going to the "top" of the triangular connector on the voltage regulator with key on and engine stopped. If none, fix the wiring between the ignition switch and regulator, and/or the ignition switch itself. If you do find line voltage on this blue wire, then check for continuity of the green wire from the voltage regulator to one of the alternator's field terminals. If none, repair the wire. Check for 0v (or minimal voltage indicating at least a passable commonality) between alternator B+ output terminal (the threaded stud) and battery poz with engine stopped. If you see 0v, your car is possessed or it is in fact charging and you're not measuring it correctly. If you see anything other than 0v, then fix the wire from the alternator B+ to the firewall main disconnect and the big terminal on the starter motor and the big terminal on the starter relay and battery poz.
If you find no fault in the wiring, that narrows it down to the alternator or the regulator. To test the alternator without removing it from the car, disconnect the wires from the "FLD" terminals on the alternator. Carefully run a jumper wire from the B+ ("BAT") output stud to one of the alternator's field ("FLD") terminals -- it doesn't matter which one. Then connect the other field terminal to ground and start the engine. Don't run it much above idle speed, for you are "full fielding" the alternator, taking the regulator out of the system, and if you rev it too high, the alternator can produce enough voltage to blow bulbs and cause other damage. If the full-fielded alternator gives you normal or near-normal light brightness, blower speed, ammeter reading, and (most importantly) voltage readings, then the alternator's probably more or less fine and the regulator becomes the prime suspect.
Be very careful with rebuilds. It's tempting to get the $24.99 "remanufactured" alternator from the parts store, complete with the "lifetime warranty", but if you want to do the repair just once, stay away from this indifferently-thrown-together junk. That "lifetime warranty" means you get to spend your "lifetime" swapping repeatedly-dead remanufactured parts under "warranty". Likewise, quality of generally-available regulators has been dropping. Get a brand-new Chrysler alternator and regulator from Old Car Parts Northwest, if you need either component. Unless you plan on upgrading the charging system wiring, specify an alternator of not more than 50 amps. See here for system upgrade info.
The system is really simple. Components are alternator, voltage regulator, ignition switch. Here's a diagram; your '71 car uses the electronic system shown on the right:
Check for line voltage at the blue wire going to the "top" of the triangular connector on the voltage regulator with key on and engine stopped. If none, fix the wiring between the ignition switch and regulator, and/or the ignition switch itself. If you do find line voltage on this blue wire, then check for continuity of the green wire from the voltage regulator to one of the alternator's field terminals. If none, repair the wire. Check for 0v (or minimal voltage indicating at least a passable commonality) between alternator B+ output terminal (the threaded stud) and battery poz with engine stopped. If you see 0v, your car is possessed or it is in fact charging and you're not measuring it correctly. If you see anything other than 0v, then fix the wire from the alternator B+ to the firewall main disconnect and the big terminal on the starter motor and the big terminal on the starter relay and battery poz.
If you find no fault in the wiring, that narrows it down to the alternator or the regulator. To test the alternator without removing it from the car, disconnect the wires from the "FLD" terminals on the alternator. Carefully run a jumper wire from the B+ ("BAT") output stud to one of the alternator's field ("FLD") terminals -- it doesn't matter which one. Then connect the other field terminal to ground and start the engine. Don't run it much above idle speed, for you are "full fielding" the alternator, taking the regulator out of the system, and if you rev it too high, the alternator can produce enough voltage to blow bulbs and cause other damage. If the full-fielded alternator gives you normal or near-normal light brightness, blower speed, ammeter reading, and (most importantly) voltage readings, then the alternator's probably more or less fine and the regulator becomes the prime suspect.
Be very careful with rebuilds. It's tempting to get the $24.99 "remanufactured" alternator from the parts store, complete with the "lifetime warranty", but if you want to do the repair just once, stay away from this indifferently-thrown-together junk. That "lifetime warranty" means you get to spend your "lifetime" swapping repeatedly-dead remanufactured parts under "warranty". Likewise, quality of generally-available regulators has been dropping. Get a brand-new Chrysler alternator and regulator from Old Car Parts Northwest, if you need either component. Unless you plan on upgrading the charging system wiring, specify an alternator of not more than 50 amps. See here for system upgrade info.
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