This is not a do-it-yourself guide to repair the Magneti Marelli

This is not a do-it-yourself guide to repair the Magneti Marelli Electronic Throttle
Module but it is a project I worked on to see if I could adapt an off-the-shelf throttle
position sensor to this particular ETM. The project may be of interest to anyone
interested in learning more about this ETM. The ETM is a crucial safety component so a
home DIY fix like this is certainly not recommended, I would recommend going to the
dealer or Xemodex if you’re having any issues with this ETM.
Figure 1 Vishay Throttle Position Sensor prior to modification for Magneti Marelli retrofit. With
some modification (cut off the mounting flange) this sensor fits well in the center area of the ETM
end plate.
Figure 2 Completed Magneti Marelli Vishay Retrofit
Figure 3 All work is done without disassembly of ETM. End plates are modified some to accept new
sensor and wiring. If anyone has attempted to disassemble one of these ETM’s you’ll know why it’s a
big benefit not to have to do disassembly.
Figure 4 Vishay sensor wires are soldered and covered in epoxy.
Figure 5 New sensor does add some width to end plate dimensions.
Figure 6 Vishay sensor housing is cut and shaped to fit center opening of end plate. Magnet is
removed from original Vishay sensor housing/holder and directly installed on end of throttle plate
shaft. Aligning and reliably attaching magnet to the shaft end was the biggest challenge in this
project. Small magnet size of the Vishay sensor was one of the primary reasons to go with this sensor.
Figure 7. Air gap between magnet and sensor IC is adjusted by filing sensor outer housing.
Figure 8 Sensor wiring soldered to exposed contact areas of end plate. No disassembly of ETM is
required with this method. Output signal is also routed to other side, which replaces the second
sensor output. Note cut in end plate contacts just above the soldered wires; the cut disconnects signal,
power and ground from original sensor.
Figure 9 Throttle position signal is required for both sides. Originally, ETM has two sensors for
redundancy and safety. New (and single) sensor output signal is supplied to both sides.
Figure 10 Wire from new sensor is brought across ETM body.
Figure 11 Retaining bracket was made to hold sensor in place. Silicone is also used for sensor
adhesion and sealant once voltage adjustments are completed. Wires are protected with high temp
split wire loom.
Figure 12 High temp epoxy is used for protection once wires are soldered to exposed contact area.
Page 43 provides the best information I’ve found on the different ETM failure modes and
the associated emergency running modes with the Bosch Motronic system. Volvo
emergency running modes may be different then what’s in the Audi link referenced but
the Motronic system is similar.
http://www.ibiblio.org/tkan/audi/2.7Biturbo-SelfStudy.pdf