Checking for parasitic draw on 69 corvette. It appears I have a newer internal voltage regulator And still hooked up to old external???

 

It may be wired for internal regulation and the external one is bypassed inside the external Reg. But if not, there is a way to bypass the Ext. Reg. I did this before but can't remember, maybe connecting the F and 1 Terminals together. But don't try it unless you can confirm the correct terminals. And the wiring on the Internally regulated Alt. is different from the Ext Reg. Alt , so what do the connections on your Alt. and the inside of the Ext. Reg. look like? Without some wiring modifications to the Ext. Reg. it won't work correctly, if at all. Sometimes the Ext. Reg. is left installed but not functioning for aesthetics.

 

All 69 Corvettes came with internal regulators.
Can you post a picture of what you think is an external regulator.

 

My mistake, it’s a horn relay. It has constant power to it even with battery disconnected, drain.

 

If you mean the junction block on the bottom of the horn relay, that's normally hot even with my no key in ignition.

 

Monterey69
Let's start over. How bad is the parasitic drain?

 

Pretty bad. I’m using a test light and found if I disconnect the terminal at the alternator, it goes out. Maybe diodes

Removed each fuse and still have a drain

 

Use a voltmeter set to AC NOT DC and connect it to large output terminal on alternator. Start engine. If you get an AC reading you have bad diodes.
Beyond that are you testing for the drain at the battery using an ammeter? If so, what is the reading?

 

I used the diode setting put the black lead on red alt post, red led to alt housing and got 1.2??? Not sure what that means.

 

To test alternator diodes with a multimeter, set the dial to the diode function (often shared with continuity, indicated by an arrow pointing to a line). With the engine off, place the red lead on the alternator casing and the black lead on the positive output terminal; a healthy diode typically shows a reading of 400–800 mV (0.4–0.8V). Reversing the leads should show "OL" or no reading.

 

Monterey69

Not understanding how you can determine value of parasitic draw with a test light??? I would use an ammeter (at the highest amp setting) between the neg batt terminal and the disconnected negative lead --- make sure everything is off because if it is drawing too many amps it'll blow the fuse in your meter.

Then....Disconnect the lead going from the starter to the Horn Relay busbar (should be 8 or 10 gauge lead). Then check to see if your parasitic draw disappears. That should split out the alternator and narrow down your search.

 

He's using a multimeter, read post 9

 

This car came with an external regulator. Can you show us the wiring modifications to convert to internal regulation. There has to be something on the firewall, where the regulator resides, to make this happen.

 

Read the whole thread. He mistook the horn relay for a external regulator.

 

I saw that. The car has an external Reg with a Int. Reg. Alt. That is my question. How was that wired?

 

What makes you think that? The alternator is identical to my 69 internal regulator alternator.

 

NO it does not.
It's a regular internally regulated car.

 

My bad, I thought in MY '69 Alts. were Ext. Reg. Still learning.

 

In 1969 Chevrolet used the Corvette only for the introduction of the internal regulator, all others still used external.

 

It's a good thing to ask. My 68 was externally regulated but I converted it. So I was looking at the thread to see "why' anybody would go backwards.