Chipping a VW Jetta ECU
To install a performance chip on a VW Jetta, Golf, or Passat model ECM from around 1995, first locate and uninstall the ECU from your car. The location of the ECM in most models is in the engine compartment, below the passenger’s side wiper assembly, as shown in the picture below:
Remove the hood seal and plastic cover over that area, then release the 68-pin harness connector by pulling the plug-end lever away from the wire harness. This releases the plug so you can remove it from the ECM computer. Now remove the bolt that secures the ECM computer to the car’s chassis and slide it out. It’s often slightly tight, but it will come out.
Put the ECM on a bench and remove the (4) #10 Torx screws that secure the computer cover, and gently slide out the heat sink and wiring terminal connector with the circuit board. Take precautions against static electricity by sitting down, grounding yourself, and touching the heat sink to balance any potential difference between the ECM and yourself.
Some 1994-1996 VW VR6 computers may have the EPROM chip soldered to the circuit board and will need to be desoldered, with a 28-pin DIL socket installed in its place, before installing the performance chip. If so, you can either desolder the chip yourself if you have electronics soldering skills, or take your car computer to a TV or electronics-trained technician to desolder it and solder the 28-pin socket in place.
If your EPROM chip is already in a socket, gently pry it out with a small flat screwdriver. Lift little by little on each side until it comes out fully, and note where pin #1 goes. (Note the notch on one end of the EPROM). You must insert the performance chip in the same orientation.
When inserting the performance EPROM chip, make sure the notch points in the same direction as the old EPROM you just pulled out. Make sure that all the pins are aligned in the socket before carefully but firmly pushing it all the way down.
After you finish, you can put everything back together and reinstall the ECM in your car. Plug in the 68-pin connector and push it until it is fully engaged. Place back the plastic cover and hood seal.
