I decided to replace all my tail lights with LED for brighter coverage. Went thru on all and then when I started the car got a "Check Rear Lights" message. When I checked, all were working very brightly. After pulling my hair and using a lot of restricted words, I called my local independent mechanic for D.S. questions? He suggested I replace all the lights with the original Incandescent(1156/1157) bulbs, and call him back. I did, message went away. When I called he said that the 'ohms' for the LEDs did not compare with those of the incandescents. That caused the message.

Anyone want a bag of 1156/1157 LEDs that set off msg for my XK8? Any solutions, I would really like the brighter LED lights. I have replaced side and interior lights with LEDs with no problems.

 

Yes, you need to install resistors to mimic the ohms of the original bulbs, I believe the ones that require it are turn signal bulbs and brake light bulbs.

This video has all the information you need:

• Skip to 12:30 where he begins talking about the tail light bulbs
• At minute 19 he begins talking about rectifiers
• At minute 27 he talks about resistors for the turn signal

You can read more at this thread: Resistors for Tail Light Conversion

 

Sam,
Several of us have been and still are trying to get this problem solved....with resistors... as soon as we get it solved it will be on the Forum....Today, the English Fog Light and the Backup Light, which I believe are 1156's can be replaced with LED's with no Warning Light problem. I have a magnified super bright LED in my Back-up Lights (Clear) Number 1156 and a Magnified (Red) 1156 in my English Fog Light with no Warning Light problem.....
as they are not hooked up to the CAN Bus.

Billy Clyde

 

They call it a false positive when the LED unit causes the system to think a bulb has blown.

Some manufacturers claim to make products which do not trigger false positives.

Found these on a site here in the UK but cannot vouch for their claims to be honest.

https://www.autobulbsdirect.co.uk/382-twenty20-cree-led-12v-p21w-canbus-bayonet-bulb.html

 

Thx all. I am now back to all incandescent bulbs, and no warning lights. I may try replacing the bulbs, one set at a time until I can get a warning.
I did find that the LED amber turn signal lights(1156) that I purchased on eBay had the tiny bayonets exactly 180 degrees apart, while the ones in my car are off set just slightly(120/240 degrees). I thought Ford had taken Jag away from the 'Lucas' electrical philosophy???

 

I recently replaced a couple of the bulbs on my '97, and thought they were 1156/57. Same size, and they sorta worked, but the actual bulb number was different. I found the original number stamped on the bulb carrier of the Jag . IIRC, it was P21W. May just be another alternative part number for the same bulb design, but I found both PN's at the auto parts store. New bulb popped in and worked.....

 

Sam,

Do not give your LED Bulbs away as you will be able to use most of them. Even today without Resistors installed you can use one of the 1156 (Clear) Bulbs as your Back-up Bulb or one of the 1156 (Red) Bulbs in you English Fog Light...Those Bulbs are not hooked-up to the Cambus system! Rather than the Plain Bulbs, I bought the Magnified Clear and Red, which cost more but are really much Brighter...(Amazon) You can use those now without the Warning Light problem......After the Resistor secrets are figured out so you can use LED's in all the sockets, we will let everyone know the secrets!
Billy Clyde

 

That's generally the plan. Starting to get quite a collection of extra parts with my 'total renovation' on my XK. Leather wrapped Steering wheel, Elm dash, etc.

 

Hey Sam,

Do you have anything else? I may be interested.

Jacob

 

Right now, I only have a bunch of only 'slightly used/new LED's. The Elm/Nav dash is complete, and in excellent condition. The taupe leather wrapped steering wheel is complete, airbag, and all switches, but it has a few scratches/scrapes on the leather. These parts were on my '06 Victory Edition. I went with a walnut/3 gauge dash, and matching steering wheel. Also have some red center wheel caps and a spare walnut shifter knob.
Priced at 1/2 eBay + shipping

Got some spare parts for a Cadillac Allante' .

"Sam's Spare Parts"