My taillight mystery

[cnm2215]

The taillights on my 73 Cuda are misbehaving and I could really use some help troubleshooting them.

Some Backstory:
I replaced fuse #4 (which was blown) with a new 20A fuse
I replaced taillight bulbs with new, brass #1157 bulbs
I replaced the passenger taillight socket (which was broken) with a Dorman socket 85860
I replaced the flasher (original part no longer worked) with a Novita EL12
Both taillight sockets appear to have a ground wire connected to them (see pic below)

Overall, the misbehaviors are:

• When the driver side taillight should be solid dim, it's off
• When the passenger side taillight should be bright, it's dim
• When the passenger side taillight should be dim, it's bright

For details, see chart below (green indicates correct behavior; red indicates bad behavior)

KEYS		HEADLIGHTS		BRAKES		TURN SIGNAL		DRIVER SIDE RESULT		PASS. SIDE RESULT
OFF		OFF		PRESSED		OFF		SOLID BRIGHT RED		SOLID DIM RED (should be solid bright)
OFF		ON		NOT PRESSED		OFF		NOTHING (should be solid dim)		SOLID BRIGHT RED (should be solid dim)
OFF		ON		PRESSED		OFF		SOLID BRIGHT RED		SOLID BRIGHT RED
ON		OFF		NOT PRESSED		LEFT TS ON		FLASHES DIM & BRIGHT RED		NOTHING
ON		OFF		NOT PRESSED		RIGHT TS ON		NOTHING		FLASHES OFF & DIM RED(should flash dim & bright)
ON		OFF		PRESSED		OFF		SOLID BRIGHT RED		SOLID DIM RED (should be solid bright)
ON		OFF		PRESSED		LEFT TS ON		FLASHES DIM & BRIGHT RED		SOLID DIM RED (should be solid bright)
ON		OFF		PRESSED		RIGHT TS ON		SOLID BRIGHT RED		FLASHES OFF & DIM (should flash dim & bright)
ON		ON		NOT PRESSED		OFF		NOTHING (should be solid dim)		BRIGHT RED (should be solid dim)
ON		ON		PRESSED		OFF		SOLID BRIGHT RED		SOLID BRIGHT RED
ON		ON		NOT PRESSED		LEFT TS ON		FLASHES DIM & BRIGHT RED		NOTHING
ON		ON		NOT PRESSED		RIGHT TS ON		NOTHING		SOLID BRIGHT RED (should flash dim & bright)
ON		ON		PRESSED		LEFT TS ON		FLASHES DIM & BRIGHT RED		SOLID BRIGHT RED
ON		ON		PRESSED		RIGHT TS ON		SOLID BRIGHT RED		SOLID BRIGHT RED (should flash DIM & BRIGHT)

[70_440-6Cuda]

at first pass seems like the brake / taillight wires are reversed on the passenger side.  Socket could be wired incorrectly

[cnm2215]

I disconnected and reversed the two wires on the passenger socket. Big improvement on that side, though still not working with brakes pressed (it's as if there isn't quite enough electricity to light both taillights bright).

Any thoughts on the driver's side taillight?  (note: I didn't do any rewiring on that one; just changed out the bulb. It has its original socket). Driver side is bright just fine, but doesn't show dim at all. (And, in my table, where it says, "FLASHES DIM & BRIGHT", it might actually be flashing OFF & BRIGHT and perhaps it's just not visibly different).

table]

KEYS		HEADLIGHTS		BRAKES		TURN SIGNAL		DRIVER SIDE RESULT		PASS. SIDE RESULT
OFF		OFF		PRESSED		OFF		SOLID BRIGHT RED		FLICKERS AND THEN NOTHING (should be solid bright red)
OFF		ON		NOT PRESSED		OFF		OFF (should be dim)		SOLID DIM RED
OFF		ON		PRESSED		OFF		SOLID BRIGHT RED		SOLID DIM RED (should be bright)
ON		OFF		NOT PRESSED		LEFT TS ON		FLASHES DIM & BRIGHT RED		NOTHING
ON		OFF		NOT PRESSED		RIGHT TS ON		NOTHING		FLASHES DIM & BRIGHT RED
ON		OFF		PRESSED		OFF		SOLID BRIGHT RED		SOLID BRIGHT RED
ON		OFF		PRESSED		LEFT TS ON		FLASHES DIM & BRIGHT RED		SOLID BRIGHT RED
ON		OFF		PRESSED		RIGHT TS ON		SOLID BRIGHT RED		FLASHES DIM & BRIGHT RED
ON		ON		NOT PRESSED		OFF		NOTHING (should be solid dim)		SOLID DIM RED
ON		ON		PRESSED		OFF		SOLID BRIGHT RED		SOLID BRIGHT RED
ON		ON		NOT PRESSED		LEFT TS ON		FLASHES DIM & BRIGHT RED		SOLID DIM RED
ON		ON		NOT PRESSED		RIGHT TS ON		NOTHING (should be solid dim)		FLASH DIM & BRIGHT RED
ON		ON		PRESSED		LEFT TS ON		FLASHES DIM & BRIGHT RED		SOLID BRIGHT RED
ON		ON		PRESSED		RIGHT TS ON		SOLID BRIGHT RED		FLASHES DIM & BRIGHT RED

Now that I understand it better...
Clearly one of the wires is for bright operation and the other is for dim operation... and if the driver side is not going dim when it should, my suspicion is that one of the two contacts on the bulb is not making a connection to the wire lead (perhaps theres a chunk of crud in there or something?) I'm gonna check that out.

[70_440-6Cuda]

It sounds like there is an issue with the sockets and bulbs making correct contact.  1 wire for the socket should be +12V when the lights are on, the other wire for the socket should be +12V when the brakes are applied. 

The flasher could be another culprit - they are very cheap and would not be the first time I had a new flasher that was defective.

Was everything working before?  Turn signal switch could also be an issue

[cnm2215]

FIXED!

No, they weren't working before (when I got the car a couple of weeks ago). There a chunk of gunk blocking one of the leads on the driver side bulb socket. All exterior lights are now working. Woo hoo!

Coming soon: interior lights.  My dome light works... and that's about it. It's dark in the car at night. I haven't yet done any troubleshooting, but I really gotta get the lights on my dashboard instruments working.

But my next priority is troubleshooting my overheating problem.

Special thanks to 70_440-6Cuda !