|
Look at the wiring diagram more carefully. There are two wires running to the positive side of the coil - one to that relay and the other to the unfused side of the fuse block that is then attached to the ignition switch. When the ignition switch is turned on it supplies the power - which flows to the coil, then through that other wire to the main relay to turn on the main relay - which in turn supplies power to the FI system. So the main relay is being controlled by the coil instead of the other way around.
The main relay powers the entire FI system - I assume they use a relay to insulate it from the 'noisy' power on the positive side of the coil - the relay pulls its power from that green wire that hooks directly to the positive battery terminal - which is as clean as you can get on a car. The fuel pump relay allows the computer to control the fuel pump.
I didn't remember it that way, but the negative side of the coil goes -through- the tach - I had remembered incorrectly that there were two wires on the negative terminal - one going to the dist and the other to the tach. So if you aren't getting switched grounding occuring at the negative terminal you can't just pull off the tach wire as I had suggested - you could unhook it at the distributor and check the distributor, then if it appeared to be working you could bypass the tach and run a temporary wire directly from the dist to the neg. coil terminal.
Here's an online 1800E wiring diagram I found:
http://www.volvo-1800.com/wiring.htm
|
