Hi, try this map Art posted elsewhere. I think it was on some other car of your years.

https://www.brickboard.com/RWD/volvo/1636835/220/240/260/280/now_issue_fuel_injection.html

It shows the the two coil relay you are talking about.
Test lights can do that for you. It is confusing with out knowing on what side of the circuit you are on.
A voltage drop of some value (?) still means the light can be on through something else or directly to ground.
If you get 0.0 volts on a voltmeter, but you know the circuit is live, the meter tell you a zero means something.
It tells you are not across the circuit.
You can be on the same side or there is a load of some magnitude or type effecting the areas in between.
A test light in the hands of someone not informed on a circuits layout or its unknown causes of things will be lost or frustrated with those very easily. IMHO.

Take a regular ole' cheapie voltmeter and play with on you kitchen table with a nine volt battery.

Make youself a circuit or using your test light (a load) and poke around with it until you figure out what a zero means and all partial numbers that show up between the nine volts can mean.

You are in to videos show me's.
I bet there are some "You Tube" basic DC tutorials out there.

When I first got a "Tube" In my life it was not used like it is today.
All I had was books with pages that needed to be turned and I needed a lamp on.

Luckily, I was born after the stinky flame and oil days but I still had lots of midnights.

Phil