On a gasser and not a Mercedes. 2 months ago I had issues with my Van that turned out to be in part 2 of the sensors. The Coolant Temp Sensor was in a place where it could not easily tested without tapping into the wires or having another connector and info on what reading I was supposed to get at what temp and there no way to read the temp easily either.

The TPS has a similar issue. But I was able to get at that but the test was kind of inconclusive because the specs are kind of loose.

It turned out to be easier to buy some new ones on eBay and wait for them to arrive. The main issue was the Coolant Temp sensor and a new one fixed that and the intermittent code that the TPS had been doing even though I had previously replaced the TPS finally cleared with the newest one I put on.

What I learned is you need to have a good solid way of connecting what ever it is you are going to hook to the testers to test them and you need the specs to compare your readings to.

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84 300D, 82 Volvo 244Gl Diesel