When I go to the car to get something out without turning on the engine and then want to lock the car the sidelights come on and don't go off. I then have to get in the car again turn on the ignition and then off, get out and lock the car and all is OK. Any ideas what is wrong or which module is playing up?

 

Finally found out what the problem was - the garage had replaced the sidelights with LEDs. I simply replaced them with "normal" bulbs and hey presto the problem was solved!

 

I have replaced my rear and front sidelights as well as license plate lights with LED and they are working fine. The reason I put in LED is that heat of conventional spiral lamp generates enough heat to melt light enclosure and socket. I replaced both rear side markers for just that reason. license plate enclosure melted socket, enclosure and lens. I have a spare assembly, but need to figure out how to replace it without damaging plastic boot panel.

 

I also have been dismayed by the melting sidelight/corroded bulb socket problem. I replaced one of the fronts (amber) with an LED bulb and it flickered constantly. Since I had obtained a package of ten, I replaced with another LED bulb, and the flickering remained. Either the bulb didn't like the power it was getting, or the other way around, I've never seen that particular issue before, so I put a normal bulb back in. Too warm, but functional.

 

I remember reading something about certain LED light bulbs may cause problem while others work fine. Pretty sure I read it somewhere in this forum. I guess in my case it was luck of draw.

 

I too replaced the numberplate bulbs with LEDs with no problem at all but the sidelights threw up the problem I described. Could very well be that certain bulbs do work

 

LEDs have a different, lower resistance than traditional bulbs, and this can cause the symptoms like flickering, etc.

This can also happen at home, especially when you replace low voltage (12V) bulbs wit LEDs and the transformer cannot cope with the different resistance. I had replaced the five bulbs of my dining room lights with LEDs and the result was flickering. After replacing one of the LEDs again with the traditional halogen bulb, all was fine.

If I read that the sidelights remained on with the LEDs, I believe that the control module could not cope with the different resistance.

Good LEDs have a resisior as compensation so that these issues do not occur, cheap ones often do not and bring on the problems described.

Best regards,

Thomas

 

On my X358 I replaced the mirror turn signals with aftermarket LEDs. They worked, but after a few seconds, began to flash at a fast rate. I soldered a resistor (47 ohms I think) across the terminals of each LED. That solved the fast flashing problem.
The problem with LEDs glowing or flashing even when turned off is related. I think the control circuits in the module are designed to work with incandescent bulbs, which work when connected to 12v but not at any other time. Their internal resistance is very low, being just a coil of wire. LEDs, on the other hand, have quite high internal resistance to current in one direction. This means that any leakage in the switching circuits in the module are enough to make the LED glow. I believe placing a resistor across the LED terminals will make it appear like the incandescent bulb it is replacing.
Some LEDs are advertised as being 'CAN bus compatible'. One way the vehicle CAN bus is used is to detect bulb failures. The low resistance of the incandescent bulb is interpreted as 'good bulb', but the high resistance of the LED is interpreted as 'bad bulb'. The 'CAN bus compatible' bulbs probably have a resistor across the LED terminals. That is why my resistor fix above worked. The CAN bus interpreted the high LED resistance in the turn signal as a failed bulb, and it brought up a warning message, and switched the signals to fast flash.
For those of us with access to a soldering iron and some resistors, the problem can be solved. Alternatively, look for LEDs that advertise as being 'CAN bus compatible'.

 

Hi Pete,

I am sorry, but I believe that you got it the wrong way, as LEDs have a lower resistance than traditional bulbs. That's why you had to solder a resistor across the terminals in order to increase the resistance of the LEDs to resolve the flashing problem.

Bulb failures are detected because when a traditional bulb failes the resistance goes to zero, and that is what is being interpreted as "bad bulb", and as LEDs have a much lower resistance, as well, they asre being interpreted as "bad bulb", as well.
You state yourself "...the 'CAN bus compatible' bulbs probably have a resistor across the LED terminals...", and it is so, because the resistor increases the resistance to make an LED compatible to an incandescent bulb.

Best regards,

Thomas

 

Something is not jiving here: lets assume Thomas is correct. Also lets assume that voltage in light socket is constant. Then power dissipated in the device, light bulb, will be V^2/R; That means that light bulb with lower resistance consumes MORE energy. That statement contradicts popular opinion that LED light are much more efficient! One thing to keep in mind that it is a Light Emitting DIODE : infinite high resistance when current flows in one direction and virtually 0 when polarity reversed. That is what Pete is saying. Diodes have some 'leakage' when polarity is going one way. I may be wrong, but I think that 'leakage' current makes makes LED emit light.
Now, remember that in our cars the controlling switch is almost always breaks ground. So, positive side of light bulb is always energized, unless fuse blown,
All 'controlled switches are semiconductor device inside Control Module. As semiconductor device, they do have leakage, all the time, even when they commanded to break the circuit. LED's are very efficient that is why they can begin to 'glow' with VERY LITTLE current. Putting resistor in parallel with LED 'sucks' low current from LED and 'dumps' it on resistor.
I have two pictures of two different LED lights that work just fine in my car. I got bunch of them on Temu for like $5, so I did not mind to break to for 'educational' purposes

 

Hi Thomas.
So if we consider an incandescent bulb, for perhaps a tail light, is a piece of wire that glows hot in a vacuum. As it is effectively a long piece of tungsten, it has a resistance of perhaps 10 Ohms. At 12 volts this has a current of 1.2 Amps. The power out is VxI to give 14.4 Watts.
The CAN bus or bulb failure unit can't easily measure the actual bulb resistance because you can only do that when power is off. What it can do is measure the current that the bulb is drawing, but switching in on momentarily. When our tail light bulb is working correctly, it will draw a current of about 1.2 Amps, and that can be measured.

When an incandescent bulb fails, generally the filament breaks, as it is very thin and delicate. When that happens, the resistance of the bulb goes from 10 Ohms to something approaching infinity, certainly many million Ohms. At this point, the value of current drawn drops to zero, because the circuit has been broken by the filament failing. The CAN bus or bulb failure unit can detect this by momentarily energizing the circuit and reading the current drawn. When the current is detected as zero, then it knows the bulb must have failed.

An LED is a semiconductor, so its resistance is very high in one direction, but low in the other. A resistance is always put in series with the LED to limit the current, but it's still quite low. The problem for us is that an LED is primarily interested in the voltage in the circuit. It is very efficient, so it draws very little current, even while it is working. Most LEDs produce the same amount of light while using about a tenth of the power of an equivalent incandescent bulb. (My home LED bulbs are rated at 5 Watts and the light output is the same as the incandescent halogen equivalent which are rated at 50 Watts.)

This is a problem for our bulb failure units, which are looking for a certain current to be drawn by the bulb. The current drawn by the LED is simply too low for the failure unit to detect. That low current is exactly the same scenario as a failed (open circuit) incandescent bulb. We can get around this by soldering a small resistor across the terminals of the LED. When the circuit is in operation, the resistor in parallel with the LED draws enough current to fool the bulb failure unit or CAN bus into thinking there's an incandescent bulb present. The LED still sees 12 Volts across its terminals so it happily produces light. Some LEDs are marketed as being CAN bus compatible, so they probably already have this resistor fitted.
The other problem with some LEDs is that the bulb failure unit periodically tests bulbs to see if they are working. An incandescent bulb is very slow to respond and takes time to heat up the coils of tungsten to white heat. The process of measuring the current is effectively invisible, as the bulb is only tested for a fraction of a second. An LED, however, is more interested in the voltage applied to it, and can respond with light output in even smaller fractions of a second than the bulb failure unit produces. So sometimes LEDs look like they are on, even when they are switched off.
I was an Air Force avionics technician for twenty years, and a biomedical technician for the following thirty, but this is just basic Ohms Law in operation. I do admit that LEDs did not come into common usage for some years, but what they are used for today is remarkable.

Kind regards,
Pete M