Hi,

Daimler Jaguar XJ40 3.6 1989

Unable to find smoke rectangular side repeaters for my car. The original right side one had metal parts totally rusted away. Bought a couple of LED side repeaters that suited the car. They work fine, but now I am not able remove the bulb failure message at dashboard.

Disconnected battery for 10 minutes, no solution.

Do I need a resistor or anything else to "fool" the BFM not to reply bulb error?

Thank you very much in advance.

 

Hi Harald,

eBay is a good place to shop for salvaged parts - if you can't find the repeaters you need, contact sellers who are offering parts from an '88/'89 car to see if they may have them.

Regarding how to fool the system, I'm no electrical or electronic engineer, but like you I assume that the Bulb Failure Modules must use a low voltage/current to test the resistance of the bulb filaments to detect an open circuit. Obviously, LEDs are diodes and don't have a resistance characteristic similar to a tungsten filament. You might be able to add a resistor in series with the LED but you would probably have to experiment to find a value that fools the system into thinking a filament is present but doesn't reduce the brightness of the LED too much. You could measure the resistance of one of the original bulbs and test a resistor of a similar value as a starting point.

I'm not sure if it would work to put a resistor in parralel with the LED because the system might just see an easier path through the LED, assuming its forward voltage threshhold is lower than the resistance through the resistor. Hopefully someone else will know for certain.

If I recall, the companies that sell aftermarket HID headlamp conversion kits also offer small add-on devices for fooling a system that would otherwise trigger a bulb-out warning lamp. I think they call them "Code Cancellers," or something like that. You might look at some of the HID systems offered on eBay for any information available on these devices.

Hopefully someone more knowledgeable will be able to offer some specific ideas.

Cheers,

Don

 

Thanks Don,

A lot of useful information here. I guess I use the LED's until I am able to find some genuine spares. It is seriously difficult to obtain original smoke repeaters. I could use newer side repeaters, but then I need to "Dremel" new holes on front wing.

Thanks a lot anyway

 

I replaced my side indicators with LED's not long ago due to the same problem. Easy solution is to grab any 50w 6ohm resistors off ebay and wire them in.

I wired mine in on the vehicle side of the harness, before the connector (in the engine bay), not the indicator side (after the connector) although it shouldn't make a difference to the operation as you just need to "bridge" the two wires with the resistor. The resistor simply tricks the computer into thinking that enough load is being drawn to negate the bulb failure trigger.

I simply spliced into the wires with press on scotch locks, one end of the resistor to the positive signal (yellow) wire, the other end to the negative (black) wire as to create a "bridge" across the wires.... Problem Solved and they look so much better than the old smoke lenses and they can also be seen a lot easier as well.

This solution can also be applied to all the other bulbs if you want to avoid the cost of CanBus LED's but just be aware that the resistors can get HOT with load so need to be either insulated or kept away from other wires or anything that may catch on fire. Insulation is not so important with the indicators as they are only in an "on" state momentarily so they won't get hot.

 

Thanks Jagfix38,

A lot of new and useful information. The original parts are discontinued so it is either to find used ones or replacements like these:

Jaguar XJ40 Direction Indicator Side Lamp (Pair) (DBC3323) - JustJagsUK.com

I will certainly try your tip, just to learn. Thanks a lot.

 

Jagfix38,

Found these on ebay, guess this is what you talk about?

2x 50W 6 OHM LED Load Resistor For Signal Turn Indicator Fog Light Lamp NO ERROR | eBay

 

Those are power resistors that can dissipate the heat generated by passing the current, which seems to confirm our suspicions that a resistor would do the trick. However, the instructions indicate that the resistor can be placed "across" (in parallel) with the bulb, which will be easier than having to cut a wire to install the resistor in series with the bulb.

I've also seen these, but I don't know if they are anything more than a resistor in a package:

HID code canceler | eBay


Cheers,

Don

 

Oddman,

Yep, they are the resistors I used. And yes, they only need be spliced in and bridged across the two indicator wires.

 

Well, the resistors did not work. Did not use the speedclips, but soldered the bridge, still got bulb error.

Guess I have to buy the bulb replacements as mentioned over.