I searched around the old threads but could not find much concerning trouble code 41. I recently swapped a LT1/4L60E into a 1971 Camaro. It has been running fine until lately it has been having a bucking problem. It idles okay but when I apply the throttle it jerks back and fourth and will not accelerate. This all happened a little later in the drive, so maybe a thermal related issues?

I nursed it home and it quit at my gate. After maybe half an hour later it re-fired and in the history codes it came up with code 41, nothing came up in the current codes. In the book it identifies 41 as a ignition control problem. Has anyone had a similar issue?

Thanks everyone!

 

What you want to pay attention to is the white wire from the black pcm connector pin 5 to the "B" terminal of the ICM. You are experiencing an intermittent connection. Could be a break in the wire or poor termination either making bad connection to the wire or from connector to pin.

 

Thanks, I checked the wire as far into the loom as possible, which is not a lot. I also checked continuity from the black PCM connector to the ICM connector, it checked out okay. Still at a loss right now, the problem is getting worse as it will not idle smoothly now.

 

That's great that you ohmed it from end to end as long as you disconnect at least one end. Which I know you did right? You may have read the actual resistance of the device the wire is connected to if you leave the wire connected.

But there is some other things you have to do. One is to wiggle the wire along it's length and also check the actual connection itself where the connectors meet.

 

A few other bits of info:
http://www.mifbody.com/DTCs/DTC 41.jpg
http://www.mifbody.com/DTCs/DTC 41_2.jpg

 

I did disconnect the connectors at each end and check for continuity. I inspected the wire and connectors as well as all the other sensors and did not see anything telling. To check the wire even further I would have to pull apart the rest of the harness. I am suspicious of something happening to the wires as there was not a problem before I moved the PCM from the engine compartment to the inside of the car.

 

Here's your sign

I thought this was the engine in a 71? no?

Your only having problem with one wire, not the entire harness. So run another wire and terminate it near the connector.

I can't even come up with a good come back for this bombshell you just laid.

 

It is in a '71. As for running a new wire, that is a dang good idea, looks like I might have a weekend experiment. I feel kind of dumb for not thinking of that.

Just as a form of clarification, would the code 41 as well as the suspicion of this particular wire be consistent with the issues the LT1 is having?

Thanks for the help guys, we are going to win over this LT1 one way or another.

 

Have you considered the possibility of the IC Module prodducing an open circuit when it heat soaks?

 

Yes the wire you are talking about is the one used to fire the ignition system by the PCM. If it looses contact, as in your case, it looses the ability to fire. Your problem is intermittent contact. We know that because your engine runs. Albeit crappy but it isn't off completely. Just another indication that you have a problem at a connector. The contact between mating pins is the suspect here which means a second wire run between connections will probably NOT correct the problem. But we shall see.

 

hello-i just did this code 41 dance on my car a couple weeks ago, it was fairly frustrating to figger out. it ended up being the connector pigtail to the coil. i found this out ONLY after buying a new opti. i just hooked up the opti electrically and with the key on, spun it by hand and did the wiggle test till i got spark on my spark tester. i also was certain that i had a fine connection at the coil and icm. i was wrong. i also replaced the pigtail connector at the icm for good measure. found both pigtails on ebay for less than 20 bucks. you can look at my previous posts and see my previous query about this code, too. hope this helps.

 

In an effort to test the ICM I took it to two AutoZone stores and they cold not test it (not a surprise really, I sort of hate AutoZone). The ICM, opti and coil are all new. Though I really don't rule those out as being the problem. Speartech put on new connectors at the coil and the ICM when he reworked the harness.

I did try that fault isolation diagram provided by meissenation but in step 3 it says to take a test light to "B+" and "C". I know what "C" is on the ICM connector but what is "B+"?

 

B+ (battery positive) is 12v battery feed. it is terminal A of the icm connector. it should show 12v with the key on. alternatively you can place one end of the light on the battery positive terminal and the other end on harness terminal C. the test light should light up. it proves out your ground circuit for the icm.

 

Okay, thanks for that clarification. I went through that entire fault isolation diagram and all the wires checked out fine. It came to the end where is states that the problem is either the ICM or the ICM connection.

I borrowed the ICM of the '94 that I know works and the '71 still bucks and will now quit when idling without warning. So that would eliminate the ICM as the problem. I am resistant to cutting wires but I think I will still try jumping the ICM terminal B wire to the PCM.

 

What do you guys think about the optispark being the culprit? It is new but not a GM unit. I read in some old threads of other members experiencing similar problems to what I am dealing with. Any thoughts? Also any opinions on the LTCC or Delteq?