[Evenprime]

In continuation of my post a couple days ago regarding the left signal slowing down when the headlights come on, everyone said they figure it was a ground issue.

I tested everything and cannot find an issue.

I decided to completely write out the wiring diagram to try to find a spot where the issue could be.
But I seem to be unable to understand how the Light-Signal controller works.

Drawing one is from the manuals. Image 2 is me writing it all out, and the 3rd one is a simplistic view without connectors etc.

What I dont understand is looking at the 3rd image, I pretend I hit the Left Turn Signal and simulated how power gets to the lights.  But what I have is 'technically' according to the drawing, at the turn signal module the green ink should also go up to H3 and spread over through RT through G1 to the right light as well which we know isnt true or both lights would come on. But they are physically connected on the drawing and it makes sense that they are when the brakes are applied.

I assume I am reading this module incorrectly but not sure how to interpret it.

Also, I have no idea what B1,G1,F1,C1 or LT E1 RT H3 mean on that unit? Additionally, is that entire unit in the turn signal unit in the steering wheel?

Im at a point where Im thinking of taking the lights all out and wiring themtogether and plugging them in just under the steering column to see if it works then as I just cant seem to find a ground fault anyway. Honestly, everything looks and measures good.

I know the images can look a bit intense but really just look at the 3rd image and follow the green ink that simulated the left signal turning on and see if you can spot where Im making a mistake?

Thanks guys

Even

 

[ToxicDoc]

It is not necessarily a ground issue, but a resistance issue, which is most commonly, but not always, a poor ground. Your flasher works by heating up. The more current that passes through, the faster it heats, and that alters the flashing cycle.

So things that can affect your flashing speed includes a poor ground, corrosion in the wires, bad terminal connections or corrosion, a lamp about to die.

The letters/numbers are just circuit names. anything inside the drawn box represents a module, or switch, etc, and you see the terminal pins for those circuits. When the switch is activated, it connects one group of circuits to the other.

Now if you are certain you've checked *all* your grounds, you can try a different flasher and a new lamp. However, first thing I'd do is turn on all the lights, check turn signals with headlights on and off, and look at every lamp outside for even a small difference in intensity. This should include your headlights, running lights, brake lights, etc.

 

[DODGEBOYS]

you also gotta realize the tail lights on the 1980-older trucks "ground" thru the tail light housing = l,d add ADD a separate ground to the body or frame

 

[dodge82273]

this happens when the ONLY parking lamps and turn signal are on ? Both left and right signals slow ?

OR only when HEADLAMPS are ON ? 

park lights = check grounds for all parking/tail lamps , check bulb sockets for contacts AND ground to bulb base
if its just left or just right signal , its on that side's bulbs/connections /grounds ... OR a bad flasher ...

headlamps only = check grounds to headlamp harness , usually screw on rad support , and bulb spade connections .

 

[SuperBurban]

In continuation of my post a couple days ago regarding the left signal slowing down when the headlights come on, everyone said they figure it was a ground issue.

Try removing the left front turn signal bulb (The one on the side, near the tire, not the one by the headlight). The see what happens when you have the turn signal, and headlights on.

Also, using a 4 way flasher in place of the turn signal flasher should fix the speed issue (well stop, not a perm fix).

Any trailer light wiring on the truck? if so, check that there is no shorting out there.

The rest, I'll have to digest, and get back. Might help to keep in mind, the 70's trucks, the hazards have priority over the brake lights (brake lights will not work when the hazards are on). the 80 changed it to the brakes having priority.

 

[KurtfromLaQuinta]

Have you ever looked at the alternator?
My old stock style alternator could barely keep up with the load needed to drive all the accessories.
I'm glad those days are over.