[bradkline]

I'm still having electrical issues with my '66 Bonneville convertible. I posted here in the past and have completed the various suggested improvements but no final solution yet to my problem which is a pulsating electrical system that is worse under load.

Here's what I've done to date, installed a rebuilt alternator, new battery cables, new battery, new NOS voltage regulator, replaced ground straps with new ones from our sponsor, and cleaned the area under the ground straps.
After completing all of these things over time it seems to be slightly better in that now the ammeter stay pretty pegged until I hit the brakes and the tailights illuminate or I turn on the headlights. At that point the dash ammeter is pulsing and so are the lights.

Here's another interesting behavior. If I have the engine turned off and the ignition switch turned onto accessory and have the radio playing all is fine. If I engage the turn
signal level and the turnsignals begin flashing, the radio sound dips each time they light so the current draw to the blinkers is pulling power from the radio feed. I've also pulled the bulkhead connectors and shined up the connections but it seems none of this corrects the problem.

This problem (outside of driving me nuts) is not too bad unless I try and drive at night and the headlights are pulsing the whole time. Hitting the brakes makes it even worse so it's either a problem on the positive side or I still have grounding issues.

I'm counting on this group including our resident electrical guru George to help me finally figure it out.

Thanks in advance guys...........

Brad Kline

[Old Goat 67]

Brad,

You should be able to isolate it down using the voltage drop method.
Do this with the problem of the radio on and turn signals flashing for ease of testing.
Engine not running, so alternator and regulator are out of the picture at that time.
Use the battery voltage (EMF) from the battery posts as a base for beginning. Make sure there isn't any major voltage pulsing there first. I'd use an analog voltmeter for this testing. It would react quicker that a digital one.
When the problem is present, walk through the circuitry going downstream from there until you see the pulsing voltage.
Remember, any resistance in the circuit will show up as a voltage drop at that point.
Be sure to keep in mind that the ground circuitry is in fact a path of conductivity back to the negative battery post, so test it also with the thought that it could be a cause of high resistance in the circuit also.
When testing for positive voltage, use a jumper wire back to the negative post of the battery as a point of constant.
When testing the ground path, use the positive post of the battery as the constant.
Use a good schematic for deciding where to check in the circuitry of the car, so you can narrow it down.

Hope that does not confuse you. Any resistance in a series circuit will cause a voltage drop and can be measured across it. Narrowing it down is where you need to isolate it down to first.

Hope this helps, I'm sure George will chime in soon, but that's my two cents from here,
Charles

[george kujanski]

Good advice from Old goat. The symptom of pulsation and voltage drop when increasing load indicate a higher-than-normal resistance in the battery feed to the ignition switch. The voltage regulator actually measures the voltage at the ignition switch so as you apply loads, the reg sees less voltage, cranks up the alt output voltage, the voltage at the ign switch rises, the reg backs it down, and the cycle repeats. There must be too much resistance in the feed, creating the time constant (cycle time of the reg).

You will need to check the cabling from the bat positive, thru the harness (there's a fusible link there that may be degraded, there's a shunt for the dash ammeter, the connection thru the bulkhead connector, and the underdash wiring.

The most probable is the fusible link; in any casemeasuring the volatge drop along the way will show you where the higher resistance is.

The bat negative must also be connected solidly to all the metal on the body.

George

[Old Goat 67]

Thanks george,

I knew you'd kick in. Good to hear from you.

Charles

[bradkline]

Thanks guys for your input. I knew I could count on this group for assistance. I need to find an analog voltmeter since mine is an electronic unit. I may not report back for a while since I will be unable to work on my car for about a week. I will try these suggestions and hope to locate the problem.

Thanks again,

Brad Kline