ETM problem - V70 2001 2.4 NA Topic is solved

Post by **volvolugnut** » 28 Oct 2020, 10:00

Do the original ETMs have can type capacitors in the electronics? That may explain the low miles and high years failure. Can type capacitors fail over time because the can seal is not perfect. Many electronic devices with can type capacitors can (no pun intended) be revived by replacing all of the capacitors.
volvolugnut

Post by **abscate** » 28 Oct 2020, 10:56

Replacing can capacitors is a Faradays work....

EngineeringBloke · Post by **EngineeringBloke** » 03 Nov 2020, 14:31

I doubt this is an issue with a failing capacitor. This car has the Magneti Marell ETM. These are known for a failing throttle position sensor.

60K miles is not much, but given the age of the car this is likely to be used locally, rather than highway driving, and so have far more stop and go, and much more throttle repositioning. This wears out the resistive track that is used to determine the throttle position. When the position signal drops out, it is a serious control failure and soon the car will not run. It could drop into limp home mode for a while and at any time, so is very dangerous - eg. a turn across traffic limited to 15 mph.

These ETM units were used on Volvos during 1999-2001. They were replaced in later years by the Bosch ETA.

The ETM has a computer and is connected by a short captive cable to the car's CANBUS to other computers in the car. It has to have operating software uploaded to work.

The more recent Bosch ETA has a motor solenoid driven by a command voltage and two output position sensor signals. These are connected to the cars ECM (Engine Control Module).

XeMODeX is a company that has provided replacement ETMs and has units that detect throttle plate position without the fragile resistive strip (contactless). However, some people have just replaced the Volvo ETM with another Volvo ETM and these are fine until they fail again.