360Valiantt
Member
So I have recently out a 360 in my 68 valiant and upgraded charging system with newer alt and vr. Now I get 16 volts at alt and the whole system pulsates any ideas? Thanks.
16 volts at alt and pulsates 68 valiant
- Thread starter 360Valiantt
- Start date
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Sedanman
67-9 Valiant specialist
Can you bring the alt in to be tested? That happened to mine and fried the fuseable link and left me stranded. It sounded like a gun shot when it blew
67Dart273
Well-Known Member
Newer? Newer what? Mopar? Denso? other?
I've written about this problem until I'm blue in the "lower regions"
Over voltage is generally caused by several causes, almost in order
VOLTAGE DROP in the wiring harness. This includes the entire circuit path all the way from the battery post to the VR IGN terminal, which not only powers the VR it is the VOLTAGE SENSE line
VOLTAGE DROP in the GROUND "path." This includes the entire path from the battery NEG post to the VR mounting flange.
Bad connections at the VR connector.
In some cases a VR that is out of spec
In more rare cases a battery that has problems
And, in some cases, one field terminal is GROUNDED. Your "new" alternator, if properly wired, has TWO field connections. One is supplied switched 12V from the ignition line, the other terminal goes to the VR. This line, green controls "the amount of ground" to regulate charging. IF THIS FIELD terminal is grounded it will charge full output
====================================
Start by disconnecting the two field leads. Use an ohmeter from each field terminal to ground. Both should be OPEN or "infinite" resistance.
Review your wiring. One field should be "switched ignition." The other field only goes one place ...........back to the VR
The VR MUST be grounded. Clean, scrape the VR and firewall and remount with star lock washers
=========================================
TEST for VOLTAGE DROP
Get a connection as close as you can to the VR IGN terminal. This will depend on how you spliced it in, might be the ballast resistor switch side. Hook you meter from there to the battery positive post. Turn the key to run, engine stopped. Voltage should NOT be above .3 v, that's 3/10 of one volt
Ground, same way. Run engine, make this test with all loads turned off, and engine running at "fast idle" or "slow cruise" RPM. Then test again with blower, lights, other heavy loads on.
Stab one probe into the top of the battery NEG post. Stab the other onto the mounting flange of the VR. Should be below .3V again, and better, very very close to ZERO volts which is perfect
If these above tests are OK, have the battery load tested. Better yet swap in a good battery to test.
If nothing else above works, replace the VR. Buy a good one.
I've written about this problem until I'm blue in the "lower regions"
Over voltage is generally caused by several causes, almost in order
VOLTAGE DROP in the wiring harness. This includes the entire circuit path all the way from the battery post to the VR IGN terminal, which not only powers the VR it is the VOLTAGE SENSE line
VOLTAGE DROP in the GROUND "path." This includes the entire path from the battery NEG post to the VR mounting flange.
Bad connections at the VR connector.
In some cases a VR that is out of spec
In more rare cases a battery that has problems
And, in some cases, one field terminal is GROUNDED. Your "new" alternator, if properly wired, has TWO field connections. One is supplied switched 12V from the ignition line, the other terminal goes to the VR. This line, green controls "the amount of ground" to regulate charging. IF THIS FIELD terminal is grounded it will charge full output
====================================
Start by disconnecting the two field leads. Use an ohmeter from each field terminal to ground. Both should be OPEN or "infinite" resistance.
Review your wiring. One field should be "switched ignition." The other field only goes one place ...........back to the VR
The VR MUST be grounded. Clean, scrape the VR and firewall and remount with star lock washers
=========================================
TEST for VOLTAGE DROP
Get a connection as close as you can to the VR IGN terminal. This will depend on how you spliced it in, might be the ballast resistor switch side. Hook you meter from there to the battery positive post. Turn the key to run, engine stopped. Voltage should NOT be above .3 v, that's 3/10 of one volt
Ground, same way. Run engine, make this test with all loads turned off, and engine running at "fast idle" or "slow cruise" RPM. Then test again with blower, lights, other heavy loads on.
Stab one probe into the top of the battery NEG post. Stab the other onto the mounting flange of the VR. Should be below .3V again, and better, very very close to ZERO volts which is perfect
If these above tests are OK, have the battery load tested. Better yet swap in a good battery to test.
If nothing else above works, replace the VR. Buy a good one.
360Valiantt
Member
Well by newer i mean 1970 so I have isolated field terminals and as you described vr is a good one. It seems as though the vr is grounded properly and have replaced the vr just to be sure. Even added another ground strap to be certain that the ground path is solid. I will run a few more tests per your instruction and see what happens thanks for the help I will let you all know if I figure it out and what the exact problem is.
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