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Hi all,

After looking on the forum without finding what I was looking for, I am writing my very first post.

While driving on the highway, I had a smell in the car. I stopped at the first exit to discover one relay was melting into the fuse box.
The relay was located in position 12 (2.5 TDI - ACV), so I assumed it was the glow plug relay.

I started looking for the reason the relais burned...
First thing I noticed is that the relay was a "644" multi purpose relay, with the command circuit in between the relay terminal 2 and 8, and between 2 and 3 as described in the technical documentations.
I checked the wiring between the Central unit (68 pins plug) and the fuse boxe, and the terminal 50 (J248 - Central unit) is connected to the relay 12 terminal 3, as it should be.
Therefore, I considered the wiring to be fine.

I am trying to understand how a relay connecting to the terminal 8 instead of 3 was able to function properly.
Is anyone aware of what is connected to terminal 8 ?
When ignition is off, it connect to the earth/ground. When putting the ignition on / engine running, it give a small resistance.

Anyway, I checked between the correct relays terminal: 2 and 3.
2 has 12 volts, when ignition key is on. (In french: 12 volts après contact).
3 has infinite resistance when ignition off, then small resistance when putting contact on, turning to infinite resistance after a few second.
This looks normal to me.

When starting the engine, the relay start again (resistance on terminal 3 lowers from infinite to a small resistance) but stays on. I stopped after 1min30 since it was starting to become quite hot.
Does anyone have an idea of what might be causing this issue ?

Any help would be really appreciated !

Regards,

Matthieu
 
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