i have these 3 wires on my 87 volvo 760 turbo. They goto the hall effect sensor. Im getting no negative pulse from the - coil, and just no ground at all there. I am getting 12 volts at the + side of coil though. So i read to check the hall effect sensor inside the distributor, then later i read how to test the hall effect with the distributor in, just by checking the 3 wires that connect to the hall effect.

Red is supposed to have 12 volts-mine is
blue is supposed to be 5 volts- mine is
black is supposed to be negative- mine is.

So this mean my hall effect sensor is bad?

Hello,

The 5v wire should only have power when triggered. With your meter connected, try turning the engine by hand and watching the reading. There should be 0v throughout most of the rotation, and 5v when triggered by the pulse wheel. This is sent to the ignition ecu and used to determine when to trigger the coil.

I hope this helps...

Joe S. - Volvo Master Technician

1988 760 Turbo w/273k miles, 1981 242 Turbo w/243k miles