Cliff426
Well-Known Member
Alternator gauge rocks back and forth sometimes at idle, then when at higher speeds goes all the way to "C"…any thoughts? Voltage regulator? or just bad gauge?
Alternator Gauge question 69 Roadrunner
- Thread starter Cliff426
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Use a multi meter.. do a few checks...Battery voltage 12 to 12.5.... Charging voltage 13.8 to 14.2..... Check Grounds at battery & engine a must...The reg MUST be well grounded. Do not just look at it & guess, make sure. remove screw clean firerwall mount with sandpaper & reinstall....check the brushes in the alternator,& that the screws that holds the brushes are tight..check the back of the ammeter for a loose connection.....
http://www.69roadrunner.net/Tech Reference/charging.pdf
http://www.69roadrunner.net/Tech Reference/charging.pdf
Cliff426
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Thanks, I will check all of that today…those manual pages you sent were great.
Cliff426
Well-Known Member
Checked all grounds and wires…all tight, clean...It was putting out over 18 volts when running, so i'm going to start with a voltage regulator…let you know next week how it goes…have to wait until it arrives, ordered a date coded one, trying to bring the car to a little higher level little by little.
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Before you just change parts test the VR .....You need to troubleshoot properly to find the problem & fix it. You want to check the wiring in the Voltage regulator circuit..What kind of system? Mechanical or Electronic VR?...
It cold be a simple fix...Wiggle wiring. You could a broken wire from the VR to the Alternator....The green field wire runs between one of the alternator fields, and the voltage regulator only.* This wire is used by the voltage regulator to control alternator field grounding.* Or more simply, this is the wire the VR uses to complete the alternator field circuit.
If your results are a good charging alternator....Reconnect the wiring at the alternator. Pull the connector off the regulator. grounf the green wire at the regulator connector. If this not a charge, the problem is in the green wire from the alternator to the regulator.
If this does show a charge, the problem is either a bad regulator, bad connection at the regulator connector, or the blue feeding 12V from the key to the regulator....
Troubleshooting book....
To test for proper charging regulation, turn off all accessories and start the engine. Then check the voltage across the two small terminals at the alternator. You’re testing the field coil terminals for a voltage near 5 volts DC. These terminals are the two small ones below the large positive terminal. Then while still connected, turn on all accessories and the voltage should be near 10 volts.
If the voltages are both high (accessories off and on), the alternator may be bad. The regulator is at fault if both the charging voltage and the field coil voltage are both either high or low.
full field the alternator........When the regulator’s control function is bypassed, the alternator runs full-field.....Chrysler models. Turn of the engine. Locate the green wire connecting the alternator field terminal to the regulator; disconnect this wire from the alternator. Connect a jumper wire from the alternator field terminal to a good ground.
2. Once the regulator has been bypassed, repeat the load test.
3. If the full-field voltage exceeds the engine-off voltage by 1/2 volt or more, the regulator is defective and must be replaced.
http://www.imperialclub.com/Repair/Electrical/charging.htm
https://www.youtube.com/watch?v=RA1v3sNfHe0
It cold be a simple fix...Wiggle wiring. You could a broken wire from the VR to the Alternator....The green field wire runs between one of the alternator fields, and the voltage regulator only.* This wire is used by the voltage regulator to control alternator field grounding.* Or more simply, this is the wire the VR uses to complete the alternator field circuit.
If your results are a good charging alternator....Reconnect the wiring at the alternator. Pull the connector off the regulator. grounf the green wire at the regulator connector. If this not a charge, the problem is in the green wire from the alternator to the regulator.
If this does show a charge, the problem is either a bad regulator, bad connection at the regulator connector, or the blue feeding 12V from the key to the regulator....
Troubleshooting book....
To test for proper charging regulation, turn off all accessories and start the engine. Then check the voltage across the two small terminals at the alternator. You’re testing the field coil terminals for a voltage near 5 volts DC. These terminals are the two small ones below the large positive terminal. Then while still connected, turn on all accessories and the voltage should be near 10 volts.
If the voltages are both high (accessories off and on), the alternator may be bad. The regulator is at fault if both the charging voltage and the field coil voltage are both either high or low.
full field the alternator........When the regulator’s control function is bypassed, the alternator runs full-field.....Chrysler models. Turn of the engine. Locate the green wire connecting the alternator field terminal to the regulator; disconnect this wire from the alternator. Connect a jumper wire from the alternator field terminal to a good ground.
2. Once the regulator has been bypassed, repeat the load test.
3. If the full-field voltage exceeds the engine-off voltage by 1/2 volt or more, the regulator is defective and must be replaced.
http://www.imperialclub.com/Repair/Electrical/charging.htm
https://www.youtube.com/watch?v=RA1v3sNfHe0
Cliff426
Well-Known Member
How this all started was I think from my own stupid mistake….I went to boost the car and the guy before me had used a red wire for negative cable (still my dumb move for being in a rush). The garage was real tight and I did it real quick…the blue fusible wire link started to smoke…I quickly pulled cables and nothing further was damaged (as far as I can see). I'm replacing the fusible link with a repro from Year One…and I'm going to change out VR anyway, because I wanted to put a date coded repro on…so hopefully i just screwed up the old one. The battery showed the right volts when car off, then I put car on, let headlights stay on for a while to de-charge system, then the volt meter read over 18 when running about 5 minutes later…. I checked the other wires..all looked good, hoping I don't need to replace alternator and battery. Will probably advice what happened in about 2 weeks when I get a chance to work on car again, when work dies down. Thanks
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Good information to know.... Hopefully the fusible link safe you from any other damage..I would do a full inspection of the charging circuit, pull apart the blkhead connector at the firewall for inspection for melted wire or connections.. It’s a good idea to clean area & use an electrical lube.....
Cliff426
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Yes, I intend on taking the bulkhead connector off, clean all the connections, etc…I saw that the fusible link that Im replacing had some green finish on the connector, so either way I need to change it out…. yes I was lucky I didn't burn everything up…. I'm also putting a black battery cable on, lol….
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