Alternator Pulse

[Topless69]

Sooo, I replaced my old round back alternator that died with a squareback dual field I had (not sure of amps). I grounded one of the fields with a metal washer and ran a heavy wire to the large post on the battery relay, but now when I start the car the interior lights are pulsing. What’s causing it to pulse like this? Did I miss something?

Thanks in advance to the electrical wizards

 

[Kendog 170]

Not 100% sure but don't you ground the field to the alt. and or bracket?

 

[Topless69]

Not 100% sure but don't you ground the field to the alt. and or bracket?

I grounded the field tab closest to the pos output lug (batt) to the alternator by removing the plastic insulating washer and putting a metal washer in its place, and added a heavy wire from the alt batt lug to the big post on the battery relay. Interior lights are pulsing like a heartbeat
Any help would be most welcome!

 

[Mattax]

added a heavy wire from the alt batt lug to the big post on the battery relay.

Do you mean the Starter Relay ! ?

I was going to ask you what the ammeter is showing.
I'll still ask you that, because it still might clue us in.

Did you charge the battery on a charger before starting?

 

[Mattax]

If could be too much field current, to too low of rpm for the alternator and pulley (hopefully you still have the old alt and pulley), to one of the windings or diodes is out of commission.

Do you have a multimeter?

With a multimeter, the battery circuit restored, and a good battery we can diagnose it.
Then if not something seriously wrong, you can decide if you want to live with or try ot address it.

 

[Topless69]

If could be too much field current, to too low of rpm for the alternator and pulley (hopefully you still have the old alt and pulley), to one of the windings or diodes is out of commission.

Do you have a multimeter?

With a multimeter, the battery circuit restored, and a good battery we can diagnose it.
Then if not something seriously wrong, you can decide if you want to live with or try ot address it.

Yes the starter relay - I’m not good when it comes to electrical.
The battery is fully charged, ammeter is hooked up but not working and the pulley on the squareback alt is smaller, so should be turning faster. I don’t have a multimeter, but I do still have the old roundback alt - took them both to O’Reilly to be checked and they said the roundback failed test but squareback is good

 

[Mattax]

Yes the starter relay - I’m not good when it comes to electrical.
The battery is fully charged, ammeter is hooked up but not working and the pulley on the squareback alt is smaller, so should be turning faster. I don’t have a multimeter, but I do still have the old roundback alt - took them both to O’Reilly to be checked and they said the roundback failed test but squareback is good

Remove the wire from the alt. Batt to the Starter relay junction, and the ammeter should read true.
Open the car door and is should show slight discharge with the dome light on. Turn on the parking lights and discharge should increase.
After starting the engine, the meter should show moderate charging and then drop to zero.
A little pulsing of charge to discharge at slow idle would indicate the alternator is not making much power at that rpm.
If it happens at higher rpm, something is wrong.
That's the best you can do on the car without a multi-meter.

O'reily's didn't happen to provide a printout or say what test the roundback failed?

If not, its unfortunately common.
A lot of the chain stores don't really provide much info (lucky if the people there even know how to hook up the older alternators).

As far as the squareback, I would think the tester would show a bad diode as A/C ripple and flag it.
If its a revised squareback, we know they need more current to create a field than the older squarebacks and roundbacks. Sometimes that's an issue at low rpm, and I beleive is often an issue for the voltage regulators.