It appears that all VWs have speedometers showing slightly higher speed than the actual. I noticed that the first time I bought the 2006 VW Jetta TDI and confimed when compared with the GPS. The difference is about 8%, so going about 60mph, the speedometer would show 65mph. I have already tried adjusting the impulse number with VCDS on 2003 and 2006 VW Jettas and it did not work so my next step is to attempt to reprogram the cluster.

The vehicle gets its speed from the front ABS sensors, and disabling those sensors (or just putting a 1.4kohm resistor across - 1.5k is close enough and will work too) will trick the ABS control module into thinking that the sensor is ok just the vehicle is not moving. Your speed shows 0mph and your your odometer does not move.

Long story short I have a spare cluster so I opened it up and I see two possible places for a software - MICRONAS CDC3217G microcontroller which has FLASH and EEPROM built in and 24C32 eeprom.

Erasing the 24C32 eeprom gets guages to get crazy and some lights come on, some keep blinking (all this done on the bench!!!)

That tell me that there is some important information in the serial eeprom, but obviously that is not the only place where the code resides.

I am thinking the analog gauges are driven by varying the signal, possibly using PWM?

Does anyone have any clues how to modify this?

Any help would be gratly appreciated!!!

Adam,

Thank you for the reply. I am checking that thread right now...