Radio on/off

[Don T.]

[Leif A.]

Re: Radio on/off

That is NOT correct. The radio should only be able to function with the key in the "ON" position or the "ACC" position...something is amiss. Either, the switch is worn (appearing to be "OFF" but actually in "ACC" mode) or there is an issue with the wiring.

[Don T.]

Re: Radio on/off

Leif
Thanks for the response. Well that brings up another question, why is the radio on when the key is off. see a little indication of some heat at that area of the switch.
Thanks in advance.

[Leif A.]

Re: Radio on/off

Don,
My electrical knowledge is limited. Someone with more expertise than I, hopefully, will come along soon and answer your electrical question. Best of luck.

[Bert L.]

Re: Radio on/off

"Bumped up"

[Richard M.]

Re: Radio on/off

There is a 3 terminal connector on the left side of the radio. The wires are...

Black - Ground(bolted to crossbrace)
Gray - Lamp(same as dash lamp circuit)
Yellow - Fused power from the fuse panel via Brown accessory circuit

Ignition switch...

IGN "on" also powers ACC. This is internal to the switch.

ACC ON only, feeds the radio, heater, wipers.

Does the heater or wipers also run key OFF? If so, the IGN switch is likely faulted, but never saw this.

Chances are someone ran the radio Yellow wire at the radio connector to constant power. Check that connector for a splice, or the fuse panel "RADIO" fuse for a jumper wire.

Rich

[Don T.]

[Richard M.]

Re: Radio on/off

Don, What is the #4 wire you speak of? I'm trying to understand how a VR could affect the ACC "Brown" circuit. It's totally isolated from the charging circuit.

I'm not near my wiring diagrams, but I don't believe the Brown ACC circuit reaches anywhere near there, albeit the only place it goes is the blower and wiper in the engine bay, but Iirc, through the main harness grommet behind the wiper motor. Not through the bulkhead.

Going from memory but I'll go over the wiring diagram later.

I'm wondering if there's a intermittent short somewhere and when you removed the bulkhead connector, something changed. Maybe in the connector or back of fuse panel...?

Rich

[Don T.]

[Richard M.]

Re: Radio on/off

Don, I now see on the wiring diagrams how that happened. Very interesting failure. Good diagnosis work! I have never seen this failure before. Thanks for following up here. Good for the knowledge database.

From the same fault, Brown also powered the blower and wiper motor feeds so if you turned on the wiper switch or blower motor, those would have worked too. The wiper uses a switched ground to operate. Blower has its own switch. I see now, your #4 wire description meant the 4th terminal in the bulkhead connector, and pulling the connector opened the path to the fuse panel Brown circuit.

Here's a diagram I modified from my GM 1967 wiring sheet showing the internal relay contact and how if stuck closed would tie Bat+ directly to the Brown ACC circuit. Very unusual failure mode and resultant failure condition..... Radio always powered!

Rich
1967_BROWN_ACC_VR_ShortKeepsRadioOn.jpg

Here's a zoomed in area showing the relay contacts.
1967_BROWN_ACC_VR_ShortKeepsRadioOn_ZoomRelay.jpg

[Don T.]

[Richard M.]

Re: Radio on/off

Yes, It shows your defective regulator was likely due to those relay contacts welded together from high current, or a loose bracket for the contacts and they stayed closed. I'd be curious if you still have it. Maybe open it up and photograph the area. Root cause analysis is good to discover for future research.

Rich

[Don T.]

Re: Radio on/off

When I opened it up the coils looked ok, the one contact was closed, but the springs on the bottom of the mounting bracket were burnt. As long as the battery was connected it always had power and the unit would be hot to the touch. I stripped the components off the mounting bracket and soldered in the solid state unit and put the original cover back on it. Sorry, no picture for reference.

[Richard M.]

Re: Radio on/off

Don, Thanks for the details of the internals. Makes sense that the contacts stayed closed if the spring failed, likely from overheat as you noticed.

Here are some photos of the VR internals for reference.

Spring that failed on yours?
Screenshot_2023-10-27-06-08-59.jpg

Upper contact. Normally open via spring tension.
Screenshot_2023-10-27-06-09-49.jpg


Screenshot_2023-10-27-06-08-38.jpg


Screenshot_2023-10-27-06-10-15.jpg

All this reminds me of a story about bad VR"s....
Years ago I restored a '67 L71 here that went overseas to Norway. The owner drove it home himself, on the 3 hour drive from the shipping terminal port. He called me as he drove it home several times. One time as he was passing through a tunnel, BB sidelines galore. I could picture him grinning as he spoke, very excited and pleased. Months prior, we spent a week together here working on finishing the restoration, engine install, etc. We became good friends and talk often.

So on his drive home he stopped to refuel, then went to restart. No.... low battery. His friend that drove him to the port had jumper cables and charged it up for a while. Then restarted it and got home safely.

Next day we spoke and had him test the charging system and discovered the stock Delco 515 VR had failed on the trip home. I had him take the cover off and inspect the contacts. The bracket rivets were loose and disabled the Field contactor. When I restored the car, it was the only engine electrical part I hadn't replaced. Go figure.

He was able to get a replacement locally and all was fine.

Your VR failure was certainly different, and educational.

Rich