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Skoda Fabia Lin communication issues
Skoda Fabia Lin communication issues
Hi there,
I`m having some wierd Lin communication issues on a 2013 Skoda Fabia.
The customer complaint is that the horn and the power windows don`t work. Also the radio controls from the steering wheel don`t work.
It has a Lin communication DTC in the BCM and also no communication DTC`s for all 4 window motors and the multifunction switch on the steering wheel.
In the wiring diagram I can see there`s a LinBus from the BCM to all 4 window motors and the multifunction switch on the steering wheel.
When I disconnect the multifunction switch on the steering wheel the power windows start working and the DTC`s in the BCM can be cleared, only the no communication DTC for the switch stays active.
I`ve scoped the Lin signal:
Switch disconnected, Lin ok
Switch connected, Lin not ok.
As you can see the switch pulls the lin signal up and destroys the communication. It has good power and ground. The switch has been replaced (twice) with a oem part and a different BCM has also been swapped out, the problem is still present.
Any ideas to why this is happening would be appreciated.
I`m having some wierd Lin communication issues on a 2013 Skoda Fabia.
The customer complaint is that the horn and the power windows don`t work. Also the radio controls from the steering wheel don`t work.
It has a Lin communication DTC in the BCM and also no communication DTC`s for all 4 window motors and the multifunction switch on the steering wheel.
In the wiring diagram I can see there`s a LinBus from the BCM to all 4 window motors and the multifunction switch on the steering wheel.
When I disconnect the multifunction switch on the steering wheel the power windows start working and the DTC`s in the BCM can be cleared, only the no communication DTC for the switch stays active.
I`ve scoped the Lin signal:
Switch disconnected, Lin ok
Switch connected, Lin not ok.
As you can see the switch pulls the lin signal up and destroys the communication. It has good power and ground. The switch has been replaced (twice) with a oem part and a different BCM has also been swapped out, the problem is still present.
Any ideas to why this is happening would be appreciated.
Re: Skoda Fabia Lin communication issues
Hi.
.
How was the voltage and grounding measured on the J453 connector?
It may be necessary to check the quality of the contact under low load.
When measured with a multimeter, everything may be fine on the connector when the unit is disconnected
But when connecting the j453 unit, a bad ground contact can cause the Lin to be pulled up to the plus.
.
How was the voltage and grounding measured on the J453 connector?
It may be necessary to check the quality of the contact under low load.
When measured with a multimeter, everything may be fine on the connector when the unit is disconnected
But when connecting the j453 unit, a bad ground contact can cause the Lin to be pulled up to the plus.
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Re: Skoda Fabia Lin communication issues
I`ve load tested the power and ground, it`s ok. I even provided the switch with a power and ground straight from the battery and connected the Lin wire at a different place in the network (window motor) to rule out any possible wiring issues. The problem stays the same. When I connect the steering wheel multifunction switch it pulls the Lin signal up.
Re: Skoda Fabia Lin communication issues
Hello. My first post on this forum 
Are you sure the coil spring (F350) is ok? The coil spring are snaping, and can cause a short when they do. That can lead to different kind og issues.
Are you sure the coil spring (F350) is ok? The coil spring are snaping, and can cause a short when they do. That can lead to different kind og issues.
Re: Skoda Fabia Lin communication issues
Yes I`m sure F350 is not the cullprit. I`ve completely bypassed it (power / ground and Lin signal) and the problem doesn`t change.
Re: Skoda Fabia Lin communication issues
I finally found the issue with this car. Turns out the OE wiring diagram is wrong. I found a different car with the same multifunction switch, in its wiring diagram pins 1 and 3 are swapped around. I wired the Fabia this way and now it works. With the pins connected wrong the switch isn`t grounded and the lin wire is connected to the ground pin.
Turns out someone was there before me and had the pins out of the plug and reinstalled them according to the diagram.
Turns out someone was there before me and had the pins out of the plug and reinstalled them according to the diagram.