1949 Directional ground issue.

[cooterbfd]

Small aggravating problem here. All new wiring, except in the column. Getting a fast blink on both sides, left actually blinks, right ends up blowing fuse. When I check wiring going to the bulbs, I'm getting like 4.2 or 42 ohms. Would that be me seeing the bulb going to ground???

Any help

[NTX5467]

On more modern harnesses, there is a ground for EACH side of the turn signal wiring, front and rear.  Just a short wire with an eyelet end to attach to the sheet metal.  Not sure if that earlier harness is "self-grounding" at those locations?

 

As the "blinkers" and brake light bulbs use the same circuit to the lamps, what happens when you step on the brakes?

 

Just some thoughts,

NTX5467

[joelj]

You can try running a temporary ground from the lamp housing to the core support. If it helps, run it permanently. I can't remember what problem I was having with turn signal/parking lights on my 49 Super not working properly but the extra ground wire corrected it. I think they intended that the housings would ground with contact to the fender alone with fleshly painted surfaces, I was not getting good enough ground.

[cooterbfd]

Thanks. I shall try this....what confuses me is the book says the left directional grounds through the right indicator bulb, and vice versa.

[joelj]

I think what they were describing is how the opposite lamp is used to illuminate the indicator lamp on the instrument panel. In their choice of words indicator lamps are on the dash, direction signal lamps are outside lamps. "Each indicator lamp (on the dash) is grounded through the opposite direction signal lamp" (on the outside)

Edited October 8, 2022 by joelj
To add detail (see edit history)

[Bloo]

2 hours ago, cooterbfd said:

what confuses me is the book says the left directional grounds through the right indicator bulb, and vice versa

I'd like to see the wiring diagram for this car. In 1953-54, Chevrolet and Pontiac (and possibly some others) used a scheme where the dashboard-mounted signal indicators ground through the bulbs on the opposite side of the car.

 

These cars have separate indicators on the dash for right and left. This detail is important. What they have done is instead of grounding the sockets of the dashboard indicators to ground as normal, they have connected them together and to the "P" terminal of the flasher. I believe this is a scheme to warn the driver of a burned out bulb on the outside of the car.

 

If your 1949 Buick is wired like this, and you still have your old original GM flasher, there should not be an issue. If you buy a new flasher today, the dashboard mounted indicators will not work correctly. The cure is to remove the dashboard indicator grounds from the flasher's "P" terminal and ground them. You also need to reverse the right and left sockets in the dash.

 

This mod is ONLY for cars wired EXACTLY as I have described above that are no longer using an original flasher, and have a problem with the dashboard indicators. Since you are having trouble with the signal lights themselves, this is probably not it.

 

4.2 and 42 ohms are wildly different. To go down that path, if you wish, you will need to figure out which. 4.2 ohms would be about an 8.5 watt bulb at 6 volts, but somewhat less in real life. Ohmmeter tests are a moving target because the resistance of the bulb changes when it is on. 42 ohms would be less than a watt. You really don't need to do this, other than maybe to check for shorts to ground.

 

The suggestion to add ground wires to the sockets at all four corners of the car is a good one. Lots of screwball problems go away when you do that. I can't really guess too much about the rest until I see a wiring diagram. Post one if you've got it.

 

If this car shares the brake light bulbs like @NTX5467 mentioned, I can tell you how that works. 90% or more of old American cars do, but at one time Buick was an exception. I'm not sure when that changed.

 

[joelj]

[Bloo]

That's exactly like the 53-54 Chevrolet-Pontiac setup, and a fairly detailed explanation of how those dash indicators work. It sure would have been nice if Chevrolet and Pontiac put that in the manual LOL.

 

If you are using an original GM flasher from 1949, or back somewhere close to that, there's nothing to do about that.

 

If you have a new flasher from NAPA or something, you need to disconnect the wire from the "P" terminal of the flasher and ground the wire. This is the wire coming off the left side of the flasher and heading over to the dash indicators on the diagram. Also, swap the positions of the two sockets in the dash. This makes the dash indicators work properly but does nothing else.

 

The rest is normal, like most American cars. It has shared brake lights. Stuff to check:

 

1) On each corner of the car, there is a wire from a good ground to each signal light socket. The factory did not do this, but do it to save your sanity....

 

2) There is a wire from the signal switch to each corner of the car. If there are any double-contact bulbs, there are 2 filaments inside. Each filament has a hot contact and the socket is the common ground. The big heavy filament is the signal (front) or the signal/brake (back). Make sure the wire coming from the signal switch goes to the big filament. You mentioned fuse blowing. It would probably pay to look inside the sockets for a short caused by something hot and bare touching a spring or whatever.

 

3) Inspect the bulbs. Are they 6 volt bulbs? If the bulbs are single-contact, make sure they have the big heavy filament and have not been substituted with some tail or park light bulbs with a tiny filament. If they are double-contact, look and see that you don't have a filament sagging enough to touch another filament inside the bulb.

 

4) Beyond that, there is a hot wire feeding the flasher (on it's "X" terminal I think), and a wire from the flasher (possibly an "L" terminal) to the turn signal switch.

 

5) There is a hot wire feeding the brake light switch. There is another wire from the brake light switch to the turn signal switch.

 

6) The dash indicators are connected to the front signals. Otherwise they would come on with the brake lights.

 

And that's the whole thing. If you have all that it can't help but work unless the switch or the flasher is bad.

 

Here's how it actually works. With the signals OFF, the turn signal switch connects both rear bulbs to the brake light switch. The brake lights work normally. When you turn a signal ON (left in this example), two things happen.

 

1) The signal switch connects the left front bulb (and one dash indicator) to the flasher.

 

2) The signal switch disconnects the left rear bulb from the brake light switch and connects it to the flasher.

 

Good luck with it. With all new wiring you have to be close. Keep us posted.

 

Edited October 8, 2022 by Bloo (see edit history)

[cooterbfd]

On 10/8/2022 at 4:10 PM, Bloo said:

That's exactly like the 53-54 Chevrolet-Pontiac setup, and a fairly detailed explanation of how those dash indicators work. It sure would have been nice if Chevrolet and Pontiac put that in the manual LOL.

 

If you are using an original GM flasher from 1949, or back somewhere close to that, there's nothing to do about that.

 

If you have a new flasher from NAPA or something, you need to disconnect the wire from the "P" terminal of the flasher and ground the wire. This is the wire coming off the left side of the flasher and heading over to the dash indicators on the diagram. Also, swap the positions of the two sockets in the dash. This makes the dash indicators work properly but does nothing else.

 

The rest is normal, like most American cars. It has shared brake lights. Stuff to check:

 

1) On each corner of the car, there is a wire from a good ground to each signal light socket. The factory did not do this, but do it to save your sanity....

 

2) There is a wire from the signal switch to each corner of the car. If there are any double-contact bulbs, there are 2 filaments inside. Each filament has a hot contact and the socket is the common ground. The big heavy filament is the signal (front) or the signal/brake (back). Make sure the wire coming from the signal switch goes to the big filament. You mentioned fuse blowing. It would probably pay to look inside the sockets for a short caused by something hot and bare touching a spring or whatever.

 

3) Inspect the bulbs. Are they 6 volt bulbs? If the bulbs are single-contact, make sure they have the big heavy filament and have not been substituted with some tail or park light bulbs with a tiny filament. If they are double-contact, look and see that you don't have a filament sagging enough to touch another filament inside the bulb.

 

4) Beyond that, there is a hot wire feeding the flasher (on it's "X" terminal I think), and a wire from the flasher (possibly an "L" terminal) to the turn signal switch.

 

5) There is a hot wire feeding the brake light switch. There is another wire from the brake light switch to the turn signal switch.

 

6) The dash indicators are connected to the front signals. Otherwise they would come on with the brake lights.

 

And that's the whole thing. If you have all that it can't help but work unless the switch or the flasher is bad.

 

Here's how it actually works. With the signals OFF, the turn signal switch connects both rear bulbs to the brake light switch. The brake lights work normally. When you turn a signal ON (left in this example), two things happen.

 

1) The signal switch connects the left front bulb (and one dash indicator) to the flasher.

 

2) The signal switch disconnects the left rear bulb from the brake light switch and connects it to the flasher.

 

Good luck with it. With all new wiring you have to be close. Keep us posted.

 

Awesome.....this is the next step then......it does have a new flasher in it......my son had added a ground to the socket from the buss ground on the radiator support..... we shall work on this next. Thanks for the advice, and thanks to Joel for posting the schematic.

[Shootey]

Great explanation Bloo. I have a 1941 Buick estate wagon which originally had only one taillight. The former owner installed a second taillight which provides a brake light and taillight. The directional lights for the wagon are in a separate unit in the center of the tailgate. The late Bill Bergstrom in a magazine article featuring his 1941 Estate Wagon observed that it would be safer to have the directional signals in the two taillight units. The center unit is small and modern drivers would likely not even know to look at it. Bergstrom advised that the way to convert would be to use the signal switch from a 1949 Roadmaster or Super and use the two-filament bulbs. Earlier Buicks had separate bulbs for the directional signals. 
I have contemplated converting my car and have acquired the 1949 switch. I am a little nervous about removing the switch from the steering column and doing the wiring. Bloo’s explanation is helpful in understanding how the whole system works. The 1948-1949 shop manual has wiring diagrams for the 1949  Super and Roadmaster separate from the Specials and the 1948’s.