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just added LED rear lights and ALL 4 lights blink instead of one side...


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I've just added the Caterham LEDs, and as the title suggest, turning on an indicator causes that side's lights to blink and also the opposite side's. the correct side seems to be brighter on the front, so switching left and right you get a brighter ring on my leds.

I have an LED blinker relay.

someone suggested adding diodes????? I don't really know what that means.

I reconnected the old lights and everything worked again. if I remove one set of lights, it seems to have the same effect with all lights blinking.


any ideas?



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I did try and look for stuff on here. thanks Jonathan.

am I right in thinking that pulling the bulb and replacing it with an LED would fix this?

otherwise people are saying the JAL relay will fix it ( I bought the same relay, just not from JAL) or that adding diodes would fix this. or maybe just replacing the whole thing with a LED..... :shrug:

thanks loads


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OK. solved.

removing the incandescent telltale resulted in the indicators working perfectly, just without the telltale. with the telltale every led blinked.

I replaced the telltale with classic car LEDs with one of their LED telltales. I was told this wouldn't work and he was 95% correct. the rear wrong LED indicator had 1 led light up dimly, with the correct LED indicator blinking as normal.

I did buy a little 8 quid diode loom that I was told (and I do believe) would fix this problem perfectly, but the other LED is so dim that you won't see it in the day and at night it'll be drowned out by the brakes.

only problem now is the reverse light not working! (but I have no proof this was working before... multimeter time ahead.

thanks all!


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"This is an interesting predicament!   I had assumed that the JAL units were literally plug and play so it would be interesting to hear if anyone else has had similar issues"

"Just to point out these were caterham not JAL."

AIUI the electrical issues are:

1 LED indicators will require a suitable relay. On old Sevens this will usually require a change. This is a straight swap. 

2 If the Seven has a single telltale light in the dash the circuit will need to be changed if you fit LED indicators or an LED tellltale. This is where the diodes come in. Kits are available.

3 If the Seven has an earth-switched reverse light it will cause problems with the Caterham LED rear lights because they use a common earth for the different circuits. Several solutions are available for this.


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I plugged in the old light. it didn't work. I plugged the light into the fog lamp and it DID work. so it's the car's fault, not the LED kit. I'll see if I can find the cause of no reverse lamp, but then it isn't an MOT requirement so....


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