What causes the Ignition Module to fail?

[wkohler]

I was able to get my car running by tapping on the ICM with the handle of a hammer. It worked fine for a while (no further tapping necessary), but eventually it just quit starting. So, I swapped in one I pulled from a 528i in the yard. Started right up. I even drove the car with this unit installed. It started a couple more times, and now it's sitting at my friend's shop with no spark. I searched and tried to read as much as I could, but I guess this issue hasn't really come up since the migration over to this format. I'm just wondering if there's another issue that could be causing these to fail. I have a new cap and rotor, good wires, new plugs and a recently-replaced coil.

[Peter Florance]

Bad solder joints.

I've fixed a few of them

[Lenny D.]

Two ICUs failing? Seems unlikely.

I had an issue at the connector. Check that carefully. Now both my ICUs work fine.

[wkohler]

It was actually a loose ground. Car runs amazingly well now.