Weird brake light turn signal issue

[RubberFloorMat]

1978 K5 blazer

Running lights all work
Reverse lights work

Brake light only drivers rear worksturn signal, same drivers side rear works. Drivers side front does not.

Pass side front signal works, rear pass does not.


I've changed bulbs, what do y'all think? The rear pass side socket bad? I put a test light on and no juice on any position except headlight/running light. Same on the drivers front signal.

 

[Kain]

had this was a socket connection, also make sure its a brake light bulb and not a reverse bulb

 

[6872xtc]

I would suspect the turn signal switch in the column. Or some of the wiring in / out of it .
It makes all of the connections regarding the turn signals and brake lights.

 

[RubberFloorMat]

I was Thinking turn signal switch too, but then I looked at the harness and it looks fairly recent. (New to me truck)

 

[6872xtc]

I wouldn't think that there would be a difference in how the wires are pinned for different vehicles.
I am stuck without looking for myself..

 

[Joe In Montana]

If this isn't downright bad sockets or corroded bulbs, then it's usually defective ground(s). Bad grounds are most times the culprit in oddball happenings like this.

Always use dielectric grease... copiously... on all bulb contacts and I like to seal any click-in sockets with some more dielectric grease especially on any gaskets.

If I don't use at least three tube of dielectric grease on my exterior bulbs, I feel I haven't used enough.,

 

[diesel4me]

I've found 2057 bulbs in sockets on old trucks that were supposed to have 1157 or 1034 bulbs--that can cause some strange issues,for one,the filaments are "reversed"...you'll have bright tail lamps and they'll light up only dimly when you step on the brakes..
A bulb with a filament that broke and touches the other filament inside the bulb can cause a lot of weird backfeed problems too...the grounds are often the source of many bulb issues too..

 

[RubberFloorMat]

yeah im going to get a multipack of new bulbs and change everything out and see whats what. I dont think its a bulb issue in the rear at least cause I swapped them side to side and nothing changed.

 

[Joe In Montana]

afterthought---- check to make sure that someone didn't force a bulb into it's socket backwards.

I've seem 1157 bulbs turned 180º
I've found 1056 bulbs in a receptacle for a 1157-type bulb, and vice versa
The 20-series bulbs a lower candlepower but then there are the 23-series bulbs!

Since the BA15D is the base-type for the dual filament bulbs that you're working with here (except for the backup lights).... the 2357 bulb then also becomes a consideration. It emits 40 candlepower on the high filament instead of 32.

This represents a 25% increase in light.

The high filament of the 2357 bulb is rated at 2.23 amps vs. 2.10 amps for the 1157, so there's not a big difference there.

An option are LED bulbs. These use less power and emit a brighter light, but do not distribute that light throughout the tail light assembly. You get a direct, bright light that is concentrated in the line of sight of the LEDs, but the remainder of the tail light will be darker.

I converted my '86 Chevy-type tail/brake lamps to full-on LEDs from a Harbor Fright trailer taillight kit. when the outer lens on the trailer lights got busted, but the inner LEDs were still good.

 

[RubberFloorMat]

Thanks for the info. This weekend I'm going to pull every bulb, replace with all new and start checking sockets.

 

[Kain]

good luck