OT 55 Pontiac wiring question.

[T120]

2 hours ago, 50mech said:

As far as I know P is only capable of providing 12+ or it's open.

 

That was also my thoughts...I've installed a couple of after market Signal - Stat Sigflare 800 units in the past on my old cars with a single flashing lamp indicator at the end of the lever indicating when the turn signals are on, either right or left, and they work fine...The wiring diagram for the 1957 Pontiac I posted in  #6 as well as your 1956 Pontiac diagram in post  #10  both make sense, with the cluster turn signal indicators, each simply wired in parallel with the front turn signal lamps and I thought as well as you that there was an error in the coloured diagram,(Post #1)...then you posted an additional schematic, the  1955 Pontiac diagram (Post #17), which confused me... ( how could both sources be wrong?) , I then deleted my Post #18,( in which I had indicated that I would wire the turn signals using X and L connections only. I agree that X and L connections are the relevant connections to make the signals work as intended using either your 1956 Pontiac diagram or the 1957 Pontiac diagram...But, then I started thinking, (sometimes dangerous, lol) , maybe the stock signal control switch and flasher units used are unique to the 1955 Pontiac...Anyhow,If I had  everything at hand in front of me I am confident I could wire things up and have it working properly... ?

[50mech]

Ok finally hit me. I looked up the pn specific to the 55 Pontiac flasher unit. It's also used on olds and Cadillac from 53-60. Each of those diagrams show the same wiring so there's no mistake here.

 

 

The only ground available here is through the load, just as is normal for the flashers heater.

 

Notice that the left hand indicator lamp is connected to the right hand signals, and vice versa.

 

So, turn on the left signal and the left lamp gets power, P gets power and passes it to both indicators.

The right hand indicator can't light because it's now wired positive to positive with no ground.

The left indicator lights because the right signal isn't on and it can use it for a ground. It just doesn't pass enough current through that tiny indicator lamp to light that signal.

 

Same way the internal heater operates when the lamp is off by grounding through it but severely limiting current.

 

Eureka!

 

 

Edited July 28, 2020 by 50mech

[50mech]

So yes to be totally original you'd need two wire sockets isolated.

Which I also found they issued a tsb in 56 making the 55 sockets available separately from the harness due to too many failures of the sockets.

Pn2963861 if it helps any.

Kind of doubt it but figured I'd pass that along.

Edited July 28, 2020 by 50mech

[T120]

7 hours ago, 50mech said:

Ok finally hit me. I looked up the pn specific to the 55 Pontiac flasher unit. It's also used on olds and Cadillac from 53-60. Each of those diagrams show the same wiring so there's no mistake here.

 

 

The only ground available here is through the load, just as is normal for the flashers heater.

 

Notice that the left hand indicator lamp is connected to the right hand signals, and vice versa.

 

So, turn on the left signal and the left lamp gets power, P gets power and passes it to both indicators.

The right hand indicator can't light because it's now wired positive to positive with no ground.

The left indicator lights because the right signal isn't on and it can use it for a ground. It just doesn't pass enough current through that tiny indicator lamp to light that signal.

 

Same way the internal heater operates when the lamp is off by grounding through it but severely limiting current.

 

Eureka!

 

 

 

Thank you for the tip on Cadillac and Oldsmobile using the same wiring configuration.I found this 1956 Oldsmobile wiring diagram in my A.E.A. manuals.It illustrates quite clearly your explanation, (with the left hand indicator connected to the right turn signal lamps)....

Edited July 28, 2020 by T120

[T120]

On 7/24/2020 at 2:10 AM, casper50 said:

no wiring gurus?

Well, I have to say, kudos for 50mech...I missed seeing that crossover on the 1955 Pontiac wiring diagram,(even with my clean reading glasses), until 50mech spotted it and posted.?