VT830 D16 550hp got a code for retarter overspeed

You can’t clean this module. Volvo sells it together with a piece of pipe that it connects to. Sensors on that pipe talks to this module and then this module converts analog signals into digital and communicate with ecm. Connecting your truck to Volvo software might help as it should show you guided diagnostic steps and might even have wiring schematics for this module or sensors on that tube. I have very limited info on your year of the engine, d16 are rare breed, dealers don’t stock many parts for them as they are hard to sell.

Maybe back in the days Volvo had some info on how to service this tube with its sensors, maybe even they sold separate sensors and miscellaneous parts but now it’s like non serviceable.

 

Take a closer look at that pipe you might find a part number on it and see if some truck junkyards sells them or on eBay.