I would like to hear your guys thoughts on this, perhaps you can help me understand why it works like it does.
Customer dropped off his '08 Commander 5.7 with a complaint of rough idle and MIL. I pulled the codes and found a P0430 (He stated that has been there a while was not concerned with it) and a code P1417-CYLINDER 7 REACTIVATION CONTROL PERFORMANCE.
The vehicle had an obvious single cylinder misfire and I determined it was cyl#7 that was not contributing. A quick current ramp test of the coil showed it was working however injector circuit was not functioning. I assumed at that point the ecm had a default strategy and shut it off. Seems logical? After looking at freeze frame data and gathering some preliminary info I wanted to see if this was a default strategy so I cleared the codes and left my current clamp on the injector. I restarted the vehicle and the injector never turned on. Not even for one pulse and the code set immediately. Fine, obviously the problem is present and I was going to move on with the test even thought the code setting criteria, according to service info had not been met.
My first step was to check the MDS solenoid resistance right from the ECM on all four, just for comparison. They all tested to be about 12ohms give or take .5ohms. Knowing know that the wiring is intact I wanted to check the MDS solenoids for operation. I put the amp clamp on the suspect bad #7 MDS control wire and commanded it on with the scan tool. The waveform showed clear operation of the solenoid, smooth buildup, pintel movement and was drawing a smidgen over an amp. I compared it to a known good and it was a exactly the same.
Well, that is pretty much the entire circuit, according to current the power feed and control are there along with function. Resistance spec is dead on the money yet the ECM is shutting off the injector. According to service info the next step is to remove the intake and inspect the oil passages and then, replace the lifers if oil passages are ok.
I figured the easiest thing to do was to use a in-cylinder test and SEE if the lifters are functioning. It sure sounded normal while cranking and relative compression did not reveal anything but better safe than sorry. Needless to say the running in cylinder test on cly #7 was about as text book as they come. So now what?
The vehicle has a code that can not be cleared and sets immediately for a problem that does not seem to exist. I determined it must be some kind of "adaptive error," if there is such a thing. So I reset all adaptives and preformed and ECU reset.
BOOM- problem solved, #7 injector fires back up and runs smooth as a kitten. Frustrated with myself for choosing the route I chose I have been digging trying to find the answer. I have test driven the vehicle cycling the MDS in and out of v4 to v8 mode about 50 times and have yet to generate this code.
So my question to you is why? How does the ECM seem to get into this funk and hang up. Reminds me of an old windows OS when you get the infinite spinning hour glass. You restart it and every thing is happy again. Am I overlooking something or can you shed some light on this subject?
First of all, good to see you here! I'm curious as to whether a connection was cleaned when the MDS connector was removed along with the ECM connector for the resistance test. Yet no circuit code, interesting. You said the code could not be cleared, permanent code? Sounds like the only way to clear was to do that ECU reset. I've worked on jaguars that just would not clear a code unless I depleted some capacitors. My two cents, for what it's worth. But sure glad to see ya in the network. Looking forward to some responses from some bright minds in this site!
Hey it's MARIO!! So being a 2006 there is no "permanent codes." I don't think mode 10 comes along till about 2010. If I am being honest it would "clear" but cycle the key once it would be pending, cycle it again and it became active.
So the only connector I had unhooked was the ECM C1, 2 and 3 and even after running the ohms check and plugging them back in and trying to clear the codes it set again immediately. This leads me to believe it was not a terminal tension issue and such. I spoke to Keith at New Level about this and he has ran across it a few times too. Just frustrating when you spend an hour running circuit checks, verifying operation and mechanical integrity just to find out you need to reboot windows haha. Any how great hearing from you!
Oh and just so I am clear this is where I did my resistance check. At ECM terminal from pin5 to ground. Current ramping was done right there to as it was very easy to get to.
Ah, ok. Had no idea the code reappeared after the resistance test. Kinda just took your post literally. Thanks for sharing about the permanent codes, I learn something every single day. Well in my opinion, if Keith D said it, case closed! Still interested in seeing who could chime in on this one 👍
We see this quite frequently in the dealership. In GM talk this is called "logic lock" Get ready to see more and more of this. This is a very common problem on infotainment systems. Radio's freak out do all sorts of goofy stuff, disconnect the battery and boom! fixed! And you will not have a repeat failure. I had a ECM do the same to me on a Malibu. I will caution about how some guys do ECM resets, DO NOT I repeat... DO NOT short battery cables together. On a start stop vehicle you let smoke out of a module from their super capacitor. I now will just disconnect the battery for around 15 minutes.
That's what I call the dealership advantage! 😉 good stuff!
Seems to me I remember this same thing happening on a nissan HVAC a few years back. Or was it the infotainment? Can't remember for sure now but I do remember that I had to de-power the unit for a few minutes and then when powered back up it worked fine.
I agree that this type of issue will become more frequent. A lot of these systems have probably hundreds of thousands of lines of code, if not more and there are bound to be glitches.
BTW, do you think putting a resistance in between the cables would make a difference? Probably not worth the risk though.
I personally do not think it is worth the risk. For me, I can write up my paper work while the battery is disconnected and the capacitors are discharging. I let the smoke out of a Power Transformer one time because I did not know. I'm lucky being in the de I looked all over SI again yesterday to find any and all information and nothing I can find is published. I did get my information from a GM factory course, I will try to look through those books and see. It may have just been the instructor telling us this I don't remember. I just remember that stuck with me.
Ah yes, those are the lessons you never forget. ;-)
I've had a couple chysler TIPM's "logic lock". One was on a jeep wrangler that the wipers would not shut off. I had disconnected the battery so they would quit wiping and when I reconnected it later it was fine. I haven't seen it back again for that issue. Very strange situation for sure!
Certain Chrysler's will leave the wipers on if there's a fault with the interior bus. Maybe someone could chime in as to whether this is just strategy or actual logic lock.
Great tip on the Stop/Starts with Super Caps!
want to know how I found that out! haha... with start stop and the back up batteries in certain onstar modules, I just do not take the chance. I can wait the 10-15 minutes. Or if I have a radio lock... if it has a fuse and I can remove power that way, I'll do it that way. We have entered a new era in faults, and some as of right now we just can not explain.
Andrew, got a 12' Sonic in right now....long story short the battery is drained. Radio illumination staying on. When running/key on the message reads "serial flash read error power mode off." No operation from the radio at all. Unplug it, snap some pics with the thermal imager (she was toasty) plug it back in and we're golden....seems to be just another case of logic lock.
I just ran into something similar. 08 dodge avenger, 3 ckp codes cel flashing 2 misfire codes, random, and cylinder 1. No misfire felt at all. Clear codes returns as soon as you drive 5ft. I've never seen a false misfire that drastic before, scoped ckp looked good, no dropouts, removed ckp inspected noticed it was newer, cleared all adaptive memory. All was normal.