LED Tail lights

So my sequentials worked fine, unless the parking/headlights were on. Once I removed the led bulbs someone had installed and replaced with standard 1157’s, all is well. Although I liked the bright illumination, it defeats the purpose if they can’t function under all scenario’s. Just my two cents.


Did you install the LED sequential and flashers? Are they WCCC brand LED’s? They will be imprinted with WCCC if they are, not all brands will work with the Cougar unique taillight systems.




Don -

I made an impulse buy just last week and got your LED taillight bulbs while purchasing the replacement vacuum tank.

I confess to not really researching the mod before purchasing.

Now, I DO have Vic’s replacement solid state sequential unit installed about 12 years ago.

I’ve not installed the bulbs yet.

Am I going to have any issues?


You’ll be fine Mark, luckily 67-68 don’t require extra mods, the bulbs are plug-and-play for your car.

Here’s our handy dandy chart showing what electronics are needed for each year to make the LED conversion work properly:

The green signal indicator arrows on your 67 and 68 dash are usually iffy at best on your 50 year old car, once you decrease the load by installing LED’s it gets worse… This is just a comfort item so technically you do not have to upgrade but I personally like all my dash lights to work so I recommend it to others.


Thanks guys for the info.

Yeah, my dash indicators have been iffy and I’ll likely step up for that relay with my next purchase.


The bulbs I removed do not say WCCC and were installed by a PO.


Have WCCC LED taillight bulbs installed in my 67 XR7 GT and look just super but the dash turn signal indicators now flash once then are steady with no blink. Lights work great however. I am running Vic’s Solid State Sequential Turn Signal Box replacement (also from WCCC).

From this tread it looks like the solution to to replace the relay with this solid state unit as well? https://secure.cougarpartscatalog.com/store/p/15520-Relay-Turn-Signal-Solid-State-K-5-/-13A366-Repro-1968-Mercury-Cougar.html?attribs=76

Totally love the way the lights work but will admit a bit disappointed that this statement on the WCCC listed for the bulbs is a bit misleading:

“1967-68 Cougar owners: you’re lucky; these will work in your car with no modifications. As you seen in the video, they work fine right out of the package whether you have the new and improved solid state sequential unit or the original mechanical unit.”

So think “these will work” a misleading statement. OK…they work. But not 100% correct. Maybe the stars will align and Don will PM me with a deal on this relay?

Going to assume that replacing the solid state box with the old perfectly functional original unit is not a solution.

If your original sequencer in the trunk works fine, then no need to replace it with a solid state version on 67 and 68s. As stated if you want your dash lights to flash, then you need the part you have link to.
69 and up is where you need to replace your entire system depending on what you decide to go with. You need to match sequencers to bulbs, etc., as they are not mix and match.
You will love your Plasma Led bulbs in your cat.
Good luck with it.

Thanks Scott. Already converted to a solid state sequential turn signal box but if a solid state signal relay is needed to make the dash indicators work correctly then i take some minor issue with the WCCC statement that their LED bulbs “will work in your car with no modifications” for 67/68 but do show the turn signal relay as “recommended” in their chart.

For other owners looking to convert their 67/68 to LED (which i totally recommend), it would be helpful to those folks to know why a new relay may be needed as contradicts “with no modifications” A least on other vendor include the relay as part of a 67/68 “LED conversion kit”. Just saying.

I know it is explained on the website that it is recommended, but it is not essential to your turn signal operation, only if you want it to blink in the car.
Until just a few years ago it would often be the case that when I pulled up to a stop light with my signal activated the dash light would stay lite. When you gave a rev it would start to flash again, which led me to believe that my alternator needed to put out more amperage. This was especially the case when you had other accessories running.
Now, with this little device, my signals always blink inside the car as well as outside.
Also I think part of the “no modifications” statement be part and parcel to the early LED bulb problems where you had to wire in a special device to keep your signal system from thinking there was a bulb out and flash really fast. We have all seen those on work trucks where they put LEDs on the back of their 1 ton cube, but nothing else, and the signals flash very fast.

I’d love to convert mine all over to LED… but having a '70 requires a pretty significant investment, between all the electronics and the bulbs themselves. I think for now I’m going to go with just the Dash LED kit, since I’ll have it torn apart for a heater core this winter.

From what I’ve read, that should be just a stand-alone, plug and play mod. Right?

I bought the dash kit for 68 XR-7, but it’s missing a couple of bulbs to do everything, so I ordered a couple more to do them all.

Reminds me of used car ads. Rust free means they are not charging you for the rust. 90% complete means by weight. Everything you need = Almost everything you need…

This has been an issue forever!
Look at a “complete” motor kit from AMK…

Anyway, the LED bulbs are a great upgrade to any of our Cougars. The reverse led’s are a must!. 67/8 are like mini spot lights out back. Dash leds do look good too. The kit to replace the dash pod light diffusers is a good way to go instead of leds, for the budget minded. Comes in 3 colors.

Mike, don’t forget the clock, radio and heater LED’s,

Thanks! That’s why I haven’t ordered the kit yet - I figured I would find 3 or 4 more bulbs I would need after I pull the dash apart, LOL!

This post is back from the dead…

I am switching to LED taillights, but WCCC taillight bulbs are out of stock, and I dont think they will be back anytime soon.

Does anyone have an LED bulb that is compatible with the WCCC SOLID STATE - TAILLIGHT SEQUENTIAL UNIT - FOR PLASMA LED BULBS - REPRO?

I found the Dorman 1157R-HP from Summit, but holy cow, they are expensive.

Actually I ordered several thousand bulbs just 2 hours ago! My previous contact in Hong Kong Retired and it took me awhile to find the right broker to handle things on my behalf over there. It will be several weeks for them to be made and air freighted over. I too have looked at several other bulbs but not only is price a factor, many of them have little difference between brake and running lights. Mine are very bright with the running lights on and BLINDING bright once the brakes are applied. My favorite is the whit bulbs for the interior, with no dome light our Cougars with dim orange incandescent bulbs look depressing at night. Install these and the interior POPS!


Awesome. That is great news Don! I just bought the LED conversion from you an hour or so ago, but was stressing on the bulbs.
I will hold off install until the new bulbs arrive!!