You always need to be careful about static discharge when dealing with semiconductors like those found inside the DME, but otherwise you were given bad advice. You absolutely need to test the harness, either by physically peeling back the rubber boots under the hood or by testing at the 35-pin in the footwell. Stop taking advice from anyone who tells you otherwise.Jinman3 wrote: Sun Sep 21, 2025 1:08 pm
I haven’t tested the harness itself and was told I shouldn’t be reading resistances on the connector with the bulkhead plugged in because it can break some transistors.
As long as you stay in contact with the body while you disconnect the DME, you should be fine. If you live in a very static-prone area (dry weather) you can always use a ground strap. There is a near endless list of things that could cause the motor to die suddenly, but the speed and ref sensor harness connections are high on the list, so not a bad place to start. The problem with intermittent problems is that you can test and everything might look fine (since 99% of the time the car is not dying). That's why wiggling the wires is a good idea -- to see if you can jostle the frayed wires enough to kill the motor.
Here's a good test for you to do. I would just add to it, and suggest someone wiggle the wires while you run the tests to see if doing that affects the readings at all...