Desperately needing help with Marelli ETM issue (1999 v70)

jtoksa · Post by **jtoksa** » 20 Mar 2022, 05:56

It failed with the symptoms, the ETM light would come on, idle rpm started rapidly fluctuating wildly at 1 second interval, gas pedal went to "on/off mode" (extremely jerky), and it would only give a minimal amount of throttle (limp home mode). Fault would reset when turning the engine off and back on, but would return after a minute or so. I replaced the position sensor with the contactless (Sacer) sensor, and I am sure I connected it right because I am an electronics hobbyist. But the fault did not go away, it still does the same thing (ETM light, jerky throttle, limp home mode). What more could I try? There are crazy fault codes which are hard to even find documentation for (p1033,p1081,p1027,p1021,p1059). I would love any advice you might be able to give me.

Post by **volvolugnut** » 20 Mar 2022, 10:55

Bad contact in the connector has been reported by others. Examine the pins for corrosion or damage.
volvolugnut

jtoksa · Post by **jtoksa** » 22 Mar 2022, 15:20

SOLVED! The Sacer sensor is a Hall-effect sensor so it comes with a magnet that is seated at the end of the throttle valve shaft, and it works by sensing the angle of the magnet. Some dickhead at the factory had installed the magnet in incorrect position by 180 degrees, in other words reversed the north and south poles. I expanded the hole in the cup where the magnet is seated, so that I could turn it freely, and, while having the sensor connected to a lab power supply and a multimeter, was able to find the position where the voltages are correct and the ETM works perfectly now.

Post by **volvolugnut** » 22 Mar 2022, 15:30

Well Done!

volvolugnut