Car won’t start. No spark. Was running fine before I did something unrelated(a week or two of messing with this car and I have forgotten what I was working on, but it had nothing to do with the electrics, and certainly not the starting system.)
Have run all the basic tests ala official shop manual and Volvo Problem Solver. Nada.
New battery.
No spark from coil
Tried the basic test and hooked a bulb to Terminal 1 of coil and ground and cranked engine - did not light
Swapped in another coil from a running car. Did not work
Hooked up my timing light to the coil (both coils),as well asto plug one, no spark - except after cranking it with no spark, got one flash at the end, I think after I finished cranking. This has happened twice.
Terminal 15 on coil is live
Terminal 1 on coil is about 1.4 volts, right where it should be
The impulse sender resistance is in range
Neither terminal of impulse sender is grounded
Have another control module, swapped it in and no change (both read about the same on the terminals that go to impulse sender - .06 volts and about .5 volts)
Continuity in wire from impulse sender to control terminal
Cleaned contacts and several grounds (engine wall by battery, windshield wiper)
Any suggestions?

 

Don't know about early model 240s, but on the 740, no spark implies bad ignition coil, bad Hall sensor on distributor or bad rpm sensor, or bad Power stage. Visit www.stepbystepvolvo.com for free diagnostic guide for 740.