New user, first post.

I am working on a friends 1987 240DL, and I'm stumped. I'm new to volvos but very good at troubleshooting cars. The car has no spark. About a month ago a new distributor was installed during a tune-up to pass smog. The connector on the old distributor broke off. It had been working fine. The car passed smog great, and ran fine for about a month.

I don't have the wiring diagram or car in front of me, so I'm omiting pin numbers etc. But you should be able to follow me.

No spark. First thing I Checked was the new distributor, because that had been changed. I pulled the distributor from the car, but left it plugged in. I unplugged the connector from the ICU, and connected the distributor (through the engine harness) to 12v and GND, and connected a resistor to the center pin and 12V. I spun the distributor by hand, and observed the signal on the center pin. So the Hall Effect Sensor is good.

Connected the ICU. Disconnected the distributor. I measured the voltage on the connecter to the distributor. 12v-5v-0v. So the ICU is powering the sensor.

I have 12v on both primary connectors on the coil. When I spin the distributor (everything connected, but the distributor out of the block) I see no AC voltage or signal on the primary terminals. Just the 12v DC.

For good measure, I tried a coil I had lying in the garage that I know works. Same result.

Unpluged the ICU and the distributor, and disconnected the coil. I tested all the wires in the engine harness. I checked that they had continuity, that there were no shorts to each other, and no shorts to 12v, and no shorts to ground. The harness seems fine. Old for sure, but electrically ok.

So from this it seems it must be the ICU. I buy a new ICU. Same result. The directions mention "contact pin sleeve" The old ICU has only 3, and none are in the female connector. I fabricate 7 more from some small copper tube and install them. Same result.

I've fiddled with the fuses, they seem ok. I'm getting 12v to the coil when the key is in run. And the ICU obviously because it is powering the hall effect sensor.

When the key is on or in start, only one of the relays under the dash energizes. The second never does. My understanding from my reading is that the second one energizes when the ICU detects the distributor is spinning.

What all does it take to make the spark in this car? If I pull the ICU and the distributor, and the coil, can I wire them on the bench, spin the distributor, and get spark? It's only 3 wires to the distributor and 2 to the coil, plus power, so that should be easy to do.

Anything that could have blown the first ICU, and then immediately blow the new one? Is there any dependency on the ECU for spark? Could wiring in that part of the harness cause an problem?

Or what else have I missed? I really want to get it to work. Even though it has over 300k miles, it shocked me by passing smog with hardly any emissions, only needing the timing set correctly to pass the "operational" test. So It seems the engine is worth saving.

 

A couple follow up questions:
Gray wire from pin 8 of the ICU to the ECU. I assume this is a pluse from the ICU to tell the ECU to fire the injector? I didn't test this wire. Does it have anything to do with a no spark situation?

Orange wire from the ICU pin 7 to the Breaker, Idle speed adjust, and ECU. What does this breaker do? Could a problem with this cause a no spark? Would I need to do anything with pin 7 if I am bench testing the ICU?

Where is this breaker and idle speed adjust located on the car? What does it look like?

If bench testing the ICU, instead of using the real distributor, can I have a resistor from pin 3 to 9, and tap pin 2 to ground (or 12v?) to simulate the hall effect sensor and create a spark? How rugged is the ICU? would a short on one of these pins risk blowing it?

 

Here is a picture of the

Throttle body sensor...and the cps...behind the block sitting atop of the transmission bellhousing...stick your hand behind the cylinder head and feel down...

these give you starting issues...

on the throttle body sensor, you should hear a click when throttle is open/closing....etc...very faint...


Just for good measure, check the crank pulley o-ring and see if it is missing or cracked...will mess with your timing...I know you stated that there is no spark and this is not so much related but would not hurt.

 

you can manually adjust the idle speed via a **** on the throttle body...black circular ****..opposite the throttle sensor I referred earlier.

Based off of Manual:
Turn the ignition switch to the ON position and open the throttle lever by hand and listen for a click as soon as the throttle comes off its stop. This test will indicate that the idle switch is functioning if you hear a click....you can wiggle the switch...buy loosening the two screws and positioning the sensor with screws centered on the sensor metal clips...or where you feel it is centered relating to the opening of the flap.