Can you interchange the ignition modules?

[eo273]

Hey there...

I've been working for days trying to diagnose what is wrong with my wife's 2001 SLS, besides the fact that it has almost 200,000 miles. Still Looks great and screams down the highway... when it's running correct

It has an intermittent problem, which is rather severe. During driving on a moments notice, the engine will suddenly begin to sputter and sounds as if it's having a severe misfire. The SES light will begin to flash, and after anywhere from a few seconds to a minute, the engine will on a dime suddenly return to normal. Electrical problem.

The only code I have is a "Random Cylinder Misfire" PO300. I also have a Driver Door Module code, but I doubt it is related.

I had a break through earlier today, after checking fuel pressure, replacing plugs, boots and so on. While the engine was sputtered and chugging, by randomly wiggling connectors, when I wiggled the electrical connector to the front ignition module, "the silver one", the car returned to normal. I managed to drive it around, and got the engine to sputtering again, and this time I popped open the hood and completely unplugged the front ignition module while it was running... NO CHANGE in the engine. I've done this ten times now.
I'm surprised I could drive on the freeway with half the engine not firing!

This connection, or the module is obviously the problem. I cleaned the prongs in the ignition module, cleaned and tightened up the female connections on the electrical connection from the harness, it keeps reoccurring. I tried shimming the connection against the valve cover to keep pressure on it as it seems to work when I am holding it, it keeps coming back while driving. I removed the electrical tape from the harness, looking for any cuts, everything looks great.

My question is, I can get a good deal for the BLACK rear ignition module from a northstar, will it interchange with the front? Or are they a different color for a reason? I've tried everything with the connector and can't seem to keep it working. I don't know if the module pins are not connected inside the module itself or what. I'm about to remove the connector and solder the wires to the ignition module itself to see if that works.

Any insight would be appreciated. Sorry for the post being so long, just wanted to explain the best I can.

[submariner409]

Even though the two cassettes have different part numbers they appear to physically the same. The only possible difference would be in the two ICM electrical connectors. Compare them before you pull the cassette.


Remove the plastic sight shield over the radiator and remove the 10mm bolts which hold the coil cassette in place. Pull the connector and cassette and check the plug boots for integrity. (Has the car recently had plugs done? This may be the time....) Make sure the cassette ground spring is seated and replace everything. Make sure the long top radiator hose is clipped into the channel under the plastic sight shield or it will rub on the w/p pulley and develop a leak.