I have replaced alt., voltage regulator, ignition module, and ballast resistor. My voltage gage in dash is bouncing all the way on the charge side. Can't figure out why. Any suggestions? Have to figure this out so i can make it to the o.c. Car show next week. Thanks again for the help!!
Voltage issues
- Thread starter GATORS340
- Start date
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Are you running a aftermarket voltage gauge?Or are you referring to the stock ammeter ?
Mopar to ya
Well-Known Member
So to be clear ... is it an ammeter gauge fluctuating or a voltmeter? Need to be sure to properly diagnose the problem. And I guess I would like to know what the reason was for replacing all the parts. What problem were you trying to fix?
They were older parts so figured i would update electronics. I guess it's an ammeter. The stock one on a 1974 duster dash gage. The one that sayes if your + or - charging. It says +40 or -40. The neddle is fluxuating almost to the +40. Hope this helps.
Common sense.Did you do any add ons witn the gauge swap?If not,check the wiring for bunt spts, or breaks.After that,swap the stock ammeter back in.
.........check ur new regulator..............kim...............
Mopar to ya
Well-Known Member
The stock 4 prong ballast plugs can't be plugged in the wrong way. There are guide holes in the ballast. At least it is on my '73. I vote with oldkimmer. Check the new voltage regulator. To you have a digital volt/ohm meter?
67Dart273
Well-Known Member
A ballast resistor WILL NOT CAUSE this problem
It might be the regulator but I doubt it
A bouncing needle USUALLY indicates a bad connection.
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Some things to check:
Get the car in the dark, or a nearly dark garage. Start the engine, open the hood, and go out and look at the alternator, rev the engine a few times. Look for a "miniature lightning show" inside the alternator windings.
IF YOU SEE THAT, what has happened is that the windings have come loose, have vibrated and scraped the insulation off the windings, replace the alternator
==========
Other things to check: The entire charge path (get a diagram) from the alternator, clear to the battery. Check the wire / end terminal at the alternator, Check the bulkhead connector, check the terminals on the ammeter, and CHECK THE HARNESS "no1 splice". (Look on your diagram) There is a big major splice inside the under-dash harness in the charge line and these can fail. In my lifetime, I've found at least 4 in different cars.
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Check for voltage drop problems in the system
To do this:
Identify the bulkhead connector pins for the alternator charge line, and the battery feed.
Make the following checks, with your voltmeter on "low volts" and the engine running to simulate "low to med. cruise" RPM
Put one probe of the meter directly onto the battery positive post, the other onto the alternator output stud. Some clip leads will be handy here.
If you see a bouncing needle/ reading, you probably have a bad connection somewhere in that harness.
Now move the probes, connected to alternator stud and the bulkhead connector where that wire enters the firewall. Look again for needle bounce
Now move so the probes are on battery positive, and and the other probe at that wire's bulkhead connection, and check again.
==========
To check for problems in the field circuit, you need to check both the ground circuit and the "hot" harness side. To do this, again, engine running
Hook one probe directly onto battery positive post, the other on "ignition run" feeding the regulator. It might be that the closest you can get is the ignition feed to the ballast resistor, traditionally "dark blue."
You are looking for a very low reading, anything over .2 (two tenths of a volt) means there is a voltage drop in the "hot" side of the circuit. This circuit is the battery, fuse link, bulkhead connector, ignition switch connector, through the switch, and back out the ignition switch connector, and back out the bulkhead on the ignition run wire.
==========
To check the regulator ground path, stab one probe directly onto the battery NEG post, the other directly onto the regulator case. Be sure to stab through the chrome/ paint. Once again, an low reading is what you want, and NOT over .2 V. A higher reading means you have a ground problem, between the battery, block, and body.
It might be the regulator but I doubt it
A bouncing needle USUALLY indicates a bad connection.
==========
Some things to check:
Get the car in the dark, or a nearly dark garage. Start the engine, open the hood, and go out and look at the alternator, rev the engine a few times. Look for a "miniature lightning show" inside the alternator windings.
IF YOU SEE THAT, what has happened is that the windings have come loose, have vibrated and scraped the insulation off the windings, replace the alternator
==========
Other things to check: The entire charge path (get a diagram) from the alternator, clear to the battery. Check the wire / end terminal at the alternator, Check the bulkhead connector, check the terminals on the ammeter, and CHECK THE HARNESS "no1 splice". (Look on your diagram) There is a big major splice inside the under-dash harness in the charge line and these can fail. In my lifetime, I've found at least 4 in different cars.
==========
Check for voltage drop problems in the system
To do this:
Identify the bulkhead connector pins for the alternator charge line, and the battery feed.
Make the following checks, with your voltmeter on "low volts" and the engine running to simulate "low to med. cruise" RPM
Put one probe of the meter directly onto the battery positive post, the other onto the alternator output stud. Some clip leads will be handy here.
If you see a bouncing needle/ reading, you probably have a bad connection somewhere in that harness.
Now move the probes, connected to alternator stud and the bulkhead connector where that wire enters the firewall. Look again for needle bounce
Now move so the probes are on battery positive, and and the other probe at that wire's bulkhead connection, and check again.
==========
To check for problems in the field circuit, you need to check both the ground circuit and the "hot" harness side. To do this, again, engine running
Hook one probe directly onto battery positive post, the other on "ignition run" feeding the regulator. It might be that the closest you can get is the ignition feed to the ballast resistor, traditionally "dark blue."
You are looking for a very low reading, anything over .2 (two tenths of a volt) means there is a voltage drop in the "hot" side of the circuit. This circuit is the battery, fuse link, bulkhead connector, ignition switch connector, through the switch, and back out the ignition switch connector, and back out the bulkhead on the ignition run wire.
==========
To check the regulator ground path, stab one probe directly onto the battery NEG post, the other directly onto the regulator case. Be sure to stab through the chrome/ paint. Once again, an low reading is what you want, and NOT over .2 V. A higher reading means you have a ground problem, between the battery, block, and body.
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