Topic: electric pulse
in Forum: C3 Electrical
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Lifetime MemberEquinunk, PA - USA
Joined: 10/31/2007
Posts: 2465
Vette(s): 1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.
I have an electrical pulse in my entire system. I recently installed a new altenator, early spring. All dash lights, and head lights pulse bright to dim as the car runs. Idle to highway speeds. The battery guage also pulses from plus to minus as the car runs. Could there be a problem with one of the diodes, maybe a ground or connection? The battery was replaced also new. Battery seems to hold a charge well, and no starting problems exist. I am thinking I have a faulty altenator. I am concerned about driving it as I do not want to get stuck away from home. Preciate all info.
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Mounds View, MN - USA
Joined: 5/24/2007
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Vette(s): 70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe
Your voltage regulator is internal in your alternator, so unless there is a mysterious intermittent massive drag on the system, the problem has to be in the alternator or its wiring. Most auto parts stores will test alternators for free.
Larry
Larry
I had something similar and found the problem was worn insulation on the battery positive cable to the starter. The wire was held to the starter by a metal clip that had worn away the insulation. On bumpy roads or at random times it would arc to ground causing the symptom.
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Duncanville, TX - USA
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Mark, did you have this issue before you changed the alternator?
If not, then you prolly got a defective alt. If you did have this problem before, then you're prolly looking at a wiring issue, perhaps a bad/corroded ground.
How fast/slow is the pulsing?
If not, then you prolly got a defective alt. If you did have this problem before, then you're prolly looking at a wiring issue, perhaps a bad/corroded ground.
How fast/slow is the pulsing?
Joel Adams
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Lifetime MemberEquinunk, PA - USA
Joined: 10/31/2007
Posts: 2465
Vette(s): 1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.
Problem did not show up till approximately 4,500 miles after the install of new alt. Starter and wires have all been rebuilt/cleaned prior to all driving this summer. I suspect a diode or heat sink has gone bad. Will be put on test machine today. Pulse is intermitant on a one second rate. Will stop for a short time, 15-20 seconds and start again.
.
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
It's possible that you have something with a small short circuit that is causing the regulator to fluctuate, and cause the "pulse". Do you have 'lectric windows, or rear defog...anything that would use a breaker circuit instead of a fuse?
We'll wait and see how the alt. test goes, but my guess is they may not test it under a full load, which would better show a malfunction. Keep us updated on that.
We'll wait and see how the alt. test goes, but my guess is they may not test it under a full load, which would better show a malfunction. Keep us updated on that.
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Lifetime MemberEquinunk, PA - USA
Joined: 10/31/2007
Posts: 2465
Vette(s): 1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.
THANKS to all who contributed to my question. YUP yessir ree bob, diode/heat sink bad. Test on dino said N/G. She'll perculate now. 
Hope the info can help someone else.
. Hope the info can help someone else.
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
in Forum: C3 Electrical
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