I got a new idea, why you do not check the not working gauges driver ic or that little motors one of them is not working. Most time the gauge motor is the problem. I repaired it a lot of time in cars. Just changed them.
I will these days write an article about how to repair a dash, I have an old dash from a Golf3 or so somewhere, it will serve nicely for this kind of article.
Maybe you can get some idea how to solve your problem...
Stay tuned on this blog site pls...

Mu best regards.

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You say Polo 6N1 hmmm..
I can't remember now how that is on that type of instrument cluster, but if I remember me correct you should have an eeprom something around 93xx or so.
You have to transfer the data from the old instrument cluster to the "new-used" one. That should be enough to make working your car and dash.
You could also physically change the eeproms too.
Take care to use the same instrument cluster from the same maker.
I assume your cluster could be a TRW cluster if so, use a TRW cluster but it could also be a VDO too. Don't mix them up.

My best regards.

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Thanks Chris. Understood. Using a Logic Analyzer also would present the communication data in real-time while investigating the various bus signals. Which is a great improvement over using a standard oscilloscope which needs to be interpreted by the user correctly first. Even a modern multimeter like the Mooshimeter that is equipped with Bluetooth and Android plus iOS support can improve investigating those signals greatly! And the Mooshimeter can also record and measure current and voltage at the same time too.

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Hi!
Thank's for supporting my article.
I probably won't fix this type of problem, because the car is too old,
but that would depend on the customers wish.
The main interest to make this article for me was to show how to use
an oscilloscope to check the communication between the ecu and the immo system.
I decide to do this on this type of car because it is an old car where are not so much thinks in the system and I assume it would help people to more understand some basics than to repair it.
To repair let's say this car, I probably deal with a corrupted eeprom/flash content and I have to reflash that memory device with a virgin content ( virgin content are content where no keys were added before and/or no setups etc. ) and add (program) new key to the car and probably make some software tweaking but not every car need that...
Another way would be to make immo off. That means, to hack the eeprom/flash content of the ecu in a way so the ecu newer ask again for a valid key from the immo box and/or the ecu is in an "unlocked" mode.
Another way for repairing this kind of problem is to buy an ecu, immo box and key with a key barrel from a donor car.
But take care with this:
1. People who sell this kind of stuff may have a copy of a key programmed inside of the ecu and immo box, so they could probably get access to your car.
2. The above listed parts MUST match each other, that means, all that parts MUST be from the same donor car.

Logic analyzer:
Not a bad tool to use it in such a situation, but after several repairing, you do not need really accurate data snaping from the system, you will recognize the patterns on the scope.
A much better tool what I would use is a CAN-Bus sniffer with a good software to interpret the communication traveling through the CAN-bus network.
Modern cars from maybe 2005 and up are equipped with CAN-bus networks and they use this network to communicate between computers in the car.
Of course, they are other protocols also in the same car too like ISO9141 or LIN bus.
Just to stay simple, the main principle is the same.
I hope my video will help somebody to understand some basics in this field.
My best regards.

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