XC70: Electrical UPGRADING TO CHEAP H7 LED CANbus GLOBES

[Agro]

Originally Posted by Tatsfield

Update: I don't know if they would have worked as the project fell at the first fence. The bulbs have rather nice moulded plugs attached to them but the connectors in the car do not fit them. So I can't install them. They are going back. Pity because they looked well made and they did say that they had built-in CANbus decoders so they might have worked.

Be great if the sensors could be disabled. Would that be possible?

[SwissXC90]

The LED lamps do not have any CANbis decoders” built in.

The LED lamps do not have anything CANbus built in.

They do not speak CANbus, they do not understand CANbus, and there is no CANbus whatsoever on the headlamp power wiring.

The headlamp lamp failure detection measures the power consumed by the lamp, typically 55W for a halogen headlamp bulb. If the power consumed is in the expected range for a normal halogen bulb, then the car knows the bulb is consuming normal power, and must be OK.

When the halogen bulb goes open circuit (fails) then the power consumed drops to zero and this triggers the bulb failure warning.

As LED lamps consume much less power than halogen lamps, they trigger the lamp failure message.
So how do they avoid triggering the lamp failure message?. They add resistors or active loads to consumer more power. But here’s where the problem lies.
Instead of the heat source being in the filament, in a inert gas, surrounded by glass cage, inside the middle of a lamp housing built to withstand the heat..., the heat generated by the LED lamp is in the electronics just at the wiring connector.

This means the heat source is now on the back of the headlamp, at the lamp connector, where a lot of plastic resides.

And this approx 50W of heat can cause heat damage.

[Tatsfield]

Not that it matters now as the lamps are going back but since LED lamps have a heat sink at the back and since it is possible to "fool" the blown bulb monitoring circuit but putting a suitable resistor in place I assumed that the CANbus claim amounted to the inclusion of such a resistor in the lamps own heat sink which would be designed to dissipate the heat. Surely the amount of heat released would not be more than that released by the current 55W halogen bulbs? I have no argument with you on the "CANbus decoder" claim but I assumed that this was just an exaggerated description of an included resistor in the base of the bulb to raise its resistance to that of a halogen bulb. If you read my post I said:

Pity because they looked well made and they did say that they had built-in CANbus decoders so they might have worked.

which merely meant that whatever the reality of their over hyped claim it may have been based on the fact that the bulbs were capable of running in a blown bulb monitoring circuit. I didn't mean I cared whether they had "built-in CANbus decoders" in reality but merely that they were making claims that the things would not trigger the warnings.

[dingov70]

Been reading this post , from an MOT point of view , if you fit LED or HID into anything other than a projector style light you risk your tester failing the car due to incorrect pattern on the beam tester . The LED looks wonderful to you , but normally is ****e for oncoming drivers due to glare from poorly constructed light sources using the prismatic reflector inaccurately

https://www.gov.uk/guidance/mot-insp...ection-4-1-1.c is the fail criteria . I have swapped HID to LED in projector lights , no issues , but remove incandescent bulbs & fit LED , Oh dear


Ballast loads to eliminate bulb failure errors are better installed outside the headlight in a cooling airflow , not easy on modern cars

[Agro]

For many years, pre LED, I've been blinded by oncoming traffic with super bright lights. I'm just joining the club.

I can confidently say that with the globes "I have tested", Halogen globes run much hotter than LED. The maxi operating temp of the LED's I've purchased is quoted to be 80degC. My standard Volvo halogens run much hotter and that's not just in the lamp housing but also right through to the connector pins and wiring.

Just have to find some bulbs that will trick the canbus system from activating the malfunction message.