Rectangular Tail Lights

[delta0014]

Has anyone had any luck hooking up the new 1 piece rectangular taillights? Using the converter they gave us? Was there anything different you had to do?

I can get the turn signals and brake lights to work. Until I put the headlights on, then nothing works except the license plate light.

If I don’t use the converter, everything works individually(tail lights, turn and brake), but you can’t hook the turn and brake lights up together ( 4 wires into 3)

Front turn/tail and headlights work normal and all gauge lights.


I literally have 2 things left (this and the hazard lights don’t work in the rear either) that I’ve been putting off for a month, but need to get it figured out so I can drop it off and the get the bodywork done.
Everything else works great and have been cruising around the neighborhood with no issues.

[delta0014]

And the chassis wiring diagram shows the Hazard Switch with pink wires to the flasher, green wire to the left front turn and a blue wire to the right front turn. Shouldn’t it have something going to the back? The hazards work up front but nothing in the back...

[GTBradley]

I’m not knowledgeable on the rectangle lights, but just saw that Caddy dad posted on 3/16 something about a “tail light converter component”, maybe check with him?

https://thefactoryfiveforum.com/showthread.php?34344-Caddy-Dad-Mk-IV-Roadster-build-Getting-closer-to-first-start&p=406753#post406753

[Caddy Dad]

Has anyone had any luck hooking up the new 1 piece rectangular taillights? Using the converter they gave us? Was there anything different you had to do?

I can get the turn signals and brake lights to work. Until I put the headlights on, then nothing works except the license plate light.

If I don’t use the converter, everything works individually(tail lights, turn and brake), but you can’t hook the turn and brake lights up together ( 4 wires into 3)

Front turn/tail and headlights work normal and all gauge lights.


I literally have 2 things left (this and the hazard lights don’t work in the rear either) that I’ve been putting off for a month, but need to get it figured out so I can drop it off and the get the bodywork done.
Everything else works great and have been cruising around the neighborhood with no issues.

I too have the square taillights and was able to connect up the converter with no issues. Its a 5 wire to 4 wire converter. I just followed the connections that were called out on the converter itself. There's nothing in the build manual about it. There are lots of variables here but are you using the standard switches that came with the kit? DPST for hazards, SPDT for turn signals? The switches are kind of daisy chained together as detailed in the schematic (check out the turn signal switch connections) and that's how the rear lights are fed. Also sounds like you might have something backfeeding the front lights? Not sure what else to say, but I'll take another look at the schematic tonight.

Any more trouble shooting details might help.

[delta0014]

Using the standard Hazard switch that came with it. Using a different turn signal from Watson’s.

It’s weird the front lights work properly.

The rear tail and brake lights work fine, until I turn the headlights on. Then the brake/turn lights in back don’t work, nor does the rear tail lights with the exception of the license plate light.
The hazard lights in the rear don’t work, maybe I missed something since the hazard switch only has wires to the front, which is what the diagram says too.

I’ll have to go back through everything tomorrow, was hoping there was an easy fix that I missed.

[cnutting]

Common problem for us 289 builders. The FFR supplied converter we had was not compatible with the LED lights. I ended up using a unit from Tekonsha. All the issues are gone. The part number is in the last post of my build thread....

[delta0014]

Thanks, that’s actually the one I have.

Which it seems to work, but the headlight switch kills it....

[delta0014]

I can put the headlights on, and there is power all the way to the lights, but they don’t light. With the headlight switch on and the turn signal on, there is power to the taillight for the turn signal but it doesn’t light up.

Turn the headlight switch off, and the turn signal will light up and blink.

[cnutting]

Interesting... Best I can offer then is to go back and trace all of the connections, sorry. Could be the headlight switch, tracing the circuits can hopefully isolate it.

[Caddy Dad]

Using the standard Hazard switch that came with it. Using a different turn signal from Watson’s.

It’s weird the front lights work properly.

The rear tail and brake lights work fine, until I turn the headlights on. Then the brake/turn lights in back don’t work, nor does the rear tail lights with the exception of the license plate light.
The hazard lights in the rear don’t work, maybe I missed something since the hazard switch only has wires to the front, which is what the diagram says too.

I’ll have to go back through everything tomorrow, was hoping there was an easy fix that I missed.

The hazard switch has wires that connect to the front, the turn indicator lights and the turn signal switch. At the turn signal switch, there are wires that then connect to the rear turn lights. Attached is a snip of the dash harness with the circuit highlighted the best I could using Paint. Check out the red and yellow paths. This doesn't explain the problem you're having, just highlighting the circuit to the rear.
126488

I'll have to take a look at the Watson's switch and I'll keep looking into your problem.

More to follow.

[Caddy Dad]

I can put the headlights on, and there is power all the way to the lights, but they don’t light. With the headlight switch on and the turn signal on, there is power to the taillight for the turn signal but it doesn’t light up.

Turn the headlight switch off, and the turn signal will light up and blink.

I'm guessing here but it sounds like you've got a bad/missing ground somewhere. The license plate light feed is tied directly to the right tail light feed. If one lights the other should too. Both lights have there own ground. Do a continuity check on your rear lights (left, right and license) all ground wires should have 0 ohms to ground and to each other. Also, what part number turn signal switch from Watson's are you using?

Still not sure why turning on headlights causes others to go out.

Hope this helps

[Caddy Dad]

I can put the headlights on, and there is power all the way to the lights, but they don’t light. With the headlight switch on and the turn signal on, there is power to the taillight for the turn signal but it doesn’t light up.

Turn the headlight switch off, and the turn signal will light up and blink.

Ah ok, I've re-read this again. I'm betting on a bad ground or with one with higher then acceptable resistance in the rear circuit somewhere. My guess is that the tail lights work just fine by themselves but when you turn on the headlights, they draw more more current than the tail lights. Thus drawing current away from the rear lights. The path with the least resistance is through the front headlights. If the resistance was equal (i.e. 0 ohms to ground) everything would be happier.

Good luck!