My 89 740 GL saga.....

Have you checked the Ignition Amplifier for corrosion on it's mounting and/or poor heatsink mounting?

All the best, Peter.

It should be kinda similar to our 85, but acknowledging the big change in '88 I could be way off....

The module we have under the dash above the brake pedal is an ignition controller, but not the "power stage." The controller sets timing, but the power stage generates the electrical fire. Our power stage is located on the fender well beside the battery, which is on the left side of the car (as the driver sees it.)

Some models/years(/locales?) also have a "radio suppression" relay that can become flaky. I don't have one so I can't help you there.

Mike

Ok....I need a little help from someone who is familiar with the '92 model 740 Gl. On the broke-down '89 model 740, I did locate an electronic module that has a heatsink and a round 5-wire connector. The Haynes diagram shows a unit with a 5-wire connector identified as an "ignition control module", not a power amplifier. "Power amplifier" is not listed! It is located just behind drivers side dash, close to the the left wall.

In looking at the diagram of this module, there are two wires going to the distributor, a brown and green one. WHat are these for? Could they be a crankcase position sensor input? Because the other fault code I am getting (besides for the AMM) is "crankcase position signal bad or missing", or something to that effect. Is there maybe a Hall-effect pickup sensing distributor rotor position? Ha! Maybe the rotor or distributor cap is bad! But if not.....I need to swap in the ignition control module from the 92 Volvo 740 and see if that is the fix. Problem is, I looked in the engine compt. and behind/underneath LH dash, and couldn't spot it. It's in a different place. I do see a similar ECM just to the right of the brake pedal....but no ignition control module. Any clue where they stashed it on the 92 model?

Yes there's a hall sensor in the distributor which tells the ignition box when to fire the coil, if that's missing the car won't run. Also it's fairly common for the connector to break off the distributor and that can break the little wires on it, I had that happen on mine once, now it's epoxied in place.

I've never seen or heard of that ignition module going bad, so you're probably barking up the wrong tree there. (Now someone will surely write and tell me about how theirs went bad.)

The ignition amplifier, aka power stage, aka ..., is located on the inner fender near the front of the car. Check between the airbox and fender. This unit switches the high current low voltage that provides the energy to the coil. This is what Peter was talking about, and is a common failure.

Your 89 non turbo won't have a hall sender in the distributor, it's the first year of the crankshaft position sensor. This is also a common failure part, and is located on the top of the bell housing, just under the distributor. And since the car won't run without it and you have a code for this...

Well, it is fixed!

Could not find an ignition amplifier ANYWHERE on the 92 turbo, so I decided to forget it and check that crankshaft position sensor out first. I found that the wires, right where they join the body of the sensor, had lost their insulation....it had just been dissolved by some grease that was on it (or maybe some sovlent/grease mixture). It was just gooey " mush", with 3 bare metal wires within an inch of the sensor. The wires were shorting, thus killing the signal. I just cleaned the grease/goo/melted wiring insulation off, and encapsulated the exposed wires in automovitve "goop" (after detemining that the stuff is a good insulator), wrapped it all up in fusion wrap, and reinstalled. On the code readout block, I reset #6 jumper (which had the two codes set) and then was getting 1-1-1 ...AMM and crank position sensor codes had cleared. It still didn't want to start, but I had the timing too far off. Finally got timing close enough, and she runs again!! I think I still do not have the timing quite right....power seems OK, but when you start up from a stop, you hear a clattering sound, I think it's ping or detonation. Didn't do that before the breakdown. I can't set timing very accurately as the timing belt cover is gone, and with it the index. The timing belt cover got torn up by a failed vibration damper a long time ago. So I noted that on the 92 turbo

Also the car had a very minor miss before this breakdown, and I just installed a new distributor cap and rotor as they were pretty worn. Well, it still has the miss...in fact seems a bit worse! All the plugs are pretty new. Only other thing is the plug wires....could one of them be causing the miss? Thanks to all , Jim

Just pick up a new timing belt cover from a junkyard, it's a good piece to have on there.

Right, and if you suspect that the timing is not set correctly, there's no point in searching further for a problem until you verify that your timing is correct. It sounds like it isn't from your symptoms. Note that you can't adjust the ignition timing even though you can move the distributor. Timing is set from that crank position sensor you fixed. However if the cam timing is off, you can have all kinds of problems. And also if any work has been done around the flywheel since the car last ran correctly, then it's possible the pickup wheel on the flywheel has been physically damaged which can give you all kinds of grief.

Fill a spray bottle with water and sparay the plugs wires while the car is running. Any insulation fault in the wiring will be obvious.

Bob