70 alternator issue

[Mike T.]

My 70 L46 had a charging problem so I changed the alternator with a NAPA rebuilt. As soon as I reconnected the battery, the emergency brake light and the seat belt warning light came on (with the key in the off position).
I turned the key to the "on" position and the two warming lights dimmed but stayed lit.
When I activated tthe turn signals, the warning lights went out completely.
An alternator rebuilder told me it was probably a defective rebuild so I got another one. Same problem.
Any ideas?
Thanks!!

[Mark E.]

Re: 70 alternator issue

Maybe someone has seen this before and can pinpoint it for you.

I haven't, but to troubleshoot I would:
- Disconnect all leads to alternator, except the ground
- Problem goes away? ==> Weird circuit issue internal to alternator
- Problem persists? ==> Check wiring. Maybe something melted down which caused initial charging problem.

Also, I've encountered weird electrical issues caused by a defective (albeit charged) battery. So look for that before tearing into it much.

[Edward J.]

Re: 70 alternator issue

Mike, did you have the same issue with the old alternator, It surely sounds like a feed back form a diode or something grounded in the case or wires, Also make sure the harness does not have any wires melted together under the tape. generally the tape will show some melting.

[Mike T.]

Re: 70 alternator issue

Didn't have the problem with the old alternator. Just the 2 new ones.
I'll start tracing all the wires ro see if any of them have melted or chafed insulation.
It wouldn't have anything to do with polarizing the alternator would it?
Thanks!

[Joe L.]

Re: 70 alternator issue

Didn't have the problem with the old alternator. Just the 2 new ones.
I'll start tracing all the wires ro see if any of them have melted or chafed insulation.
It wouldn't have anything to do with polarizing the alternator would it?
Thanks!

Mike------

Alternators don't need to be "polarized". If I was you, I'd re-install the old alternator and see if the problem persists with it. If it doesn't, then you know there is something awry with the replacement alternators. It does sound unusual that you would get two defective rebuilds. However, there might be some defective component that the rebuilder is using. In that case I'd try a rebuilt alternator from a different source.

If the problem persists with the old alternator installed, then you know that you damaged some other component of your electrical system when you replaced the alternator.

[Richard M.]

Re: 70 alternator issue

Exactly what was the charging problem originally?

Since those 2 indicator lamps are only powered with IGN on, I would think there is some form of Ground problem in the electrical system. It may be trying to find ground through the lamp filaments in that circuit.

Rich

[Richard M.]

Re: 70 alternator issue

I won't yet totally rule out a ground issue so check all grounds first, battery terminals, chassis ground cable, etc. Also ensure your battery is fully charged.

But thinking more about this... Based on the fact that those 2 dash lamps went out when you toggled the directional switch sparked some thoughts.

I spent some time looking online at a 1970 Wiring Diagram. The circuit to feed those 2 indicator lamps is a Pink wire from IGN on. This also feeds the Directional switch Flasher.

The Directional switch also has constant power, when Brake applied, from the Brake Pedal Switch(White) to power the Brake Lamps. When you turn on the directional, the Brake Lamp circuit for that side is disconnected then connected to the Directional Lamp. Check Brake Lamps operation.

One test would be to disconnect the Directional switch plug under the dash and retry if those dash lamps go out. Another option is to pull the Brake Lamp switch plug, or pull the fuse for the Brake Lamps. If you get dash lamp results to change you may want to check Rear Brake Lamps and their sockets and grounds.

Another thought is the Hazard Lamps circuit. The Brake Lamp main fuse panel feed circuit(Orange) also provides constant power to the Hazard switch from the 4-Way flasher. Check to make sure that switch is Off and then check when ON and if Hazard lampss work.

I also see a Key Buzzer function which appears to pass through the Directional switch harness. I think that also has Constant power too.

For reference, the Orange feed circuit from the fuse panel for these circuits also powers the interior courtesy lamps. These also pass through the rheostat in the Headlamp switch so check that operation too.

You may have a Directional Lamp switch, Hazard Lamp switch or associated wiring issue and this may be totally isolated from the Alternator change.

It seems unlikely to me that the alternator is causing this oddity.

Rich

[Richard M.]

Re: 70 alternator issue

I found a wiring diagram of the Key Buzzer circuit at the bottom of a 1972 Wiring Diagram. It switches Ground at the Key tumbler so that is not a power source.

Rich

[Mike T.]

Re: 70 alternator issue

Good news!
I reinstalled the old alternator and the dash lights didn't come on (like they had with the 2 new (rebuilt) NAPA alternators.
Went to Autozone to see if it was something with the NAPA rebuilds that caused the issue.
The Autozone rebuilt alternator had to be "clocked," but I installed it last night and the Emergency Brake light and the Seat Belt Warning
Light didn't come on! Good detective work Joe!
I haven't started it yet to make sure it charges OK, but hopefully this is the end of my problem.
Thanks Joe, Rich and Ed!!

[Richard M.]

Re: 70 alternator issue

Good news!
I reinstalled the old alternator and the dash lights didn't come on (like they had with the 2 new (rebuilt) NAPA alternators.
Went to Autozone to see if it was something with the NAPA rebuilds that caused the issue.
The Autozone rebuilt alternator had to be "clocked," but I installed it last night and the Emergency Brake light and the Seat Belt Warning
Light didn't come on! Good detective work Joe!
I haven't started it yet to make sure it charges OK, but hopefully this is the end of my problem.
Thanks Joe, Rich and Ed!!

Mike, Strange but I just don't understand the alternator causing this, particularly when the directional switch toggling affected results with the Napa rebuilds. Did you do anything else, tighten grounds, charge battery, etc? Did you toggle the directionals with the new AZ unit?

Also, I asked earlier and maybe you missed the question..... what was the original problem with the old alternator?

I'm not saying I'm 100% sure about the 2 Napa alternators, and maybe something I've never seen before, but this is very strange. My gut feel is there was a intermittent open ground or short somewhere in the car, then disappeared, and it may come back.... i.e. a ghost.

Please report back when the charging circuit is checked(voltmeter with engine running) and all electrical functions are verified, especially the brake lamps, directionals, hazards, horn, key buzzer, etc.

Rich