Where to tap speed sensor signal?

[Lord Popgun]

Egleaves, you need to understand that the line from the Meters to the ECU is a bi-directional serial data line. Data goes back and forth. Its not just a stream of speed data to the ECU. Don’t mess with the serial line.

Dubs, it is not unusual in electronic circuits to have circuits or parts of circuits not connected to chassis ground. My guess is the speed sensor, a Hall effect device, outputs on +and - to a receiver, like maybe an op amp, and outputs a single pulse to the rest of the circuitry in the Meter assm. It gets a little involved for a discussion here, but no chassis ground is needed in a circuit like this. Although the receiver chip most likely has power and a chassis ground. Confused yet

If it cools off some and I feel like it, maybe I’ll put a scope on the line and see whats up. Maybe.