Intermittent Electrical Gremlins [SOLVED - damaged TCM harness]

[ae7456t]

This is a continuation of an ongoing saga, but the issue has changed, so starting a new thread.

Recently I had my transmission swapped with a used one...In the course of that swap, the car developed quite the electrical problem with a ton of lights coming on, when the car is started, and hard shifting when put into gear. The shop cleaned off a ton of ground locations, and replaced the IPDM, and presto, the lights were gone, and the car ran great.

The car ran great for 1 week, then, Sunday, I took the car out, and the lights came back on, along with the hard shifting. I shut the car down, paused, restarted it, and the lights were gone and everything ran great. Same thing happened on Monday, but the lights reset when I shut it down, and all was good.

Tuesday morning, the car would crank but not start...I eventually got it to start, and immediately got the following...Tire Pressure Waning (!), VDC Off, ABS, Brake, Slip, AWD, AFS OFF, blinking SES (code U1000), no shift position indicator (PDNR), Tachometer that would go to "0", then back up to 800, headlights and dash lights that would turn themselves on/off, radiator fan that would turn itself to high, then back off, and probably a few others I have forgotten...The car seems possessed, quite frankly.

I disconnected the negative battery cable, and left it for the day. When I came home that night, I reconnected the cable, started it, and got all the same lights. I disconnected the negative battery lead, again, and took off the passenger side glovebox/dash. I found a wire bundle that looked like it was supposed to be attached to a bolt, near the BCM, so I reattached that massive connector...Right afterwards, I reconnected the battery, started it, and all the lights were gone...Back to normal!

Thinking I had solved the problem, I shut it down, buttoned it all up, started it, and, again, all was normal...Drove it to the grocery store, shut it off, came back out of the store and it started right up...Everything normal.

This morning, with an air of overconfidence, I got in, pushed the button to start, crank but no start. Second time, crank but no start. Third time, start, but all of my favorite warning lights and symptoms from above are back. Disconnected the negative battery cable, and left it.

I am seeking the collective wisdom of this forum, but here is what I am thinking, as I am grasping at straws:
1. Grounding Issue - Something under the passenger dash (or elsewhere) is intermittently not grounded.
2. Wire Shorted - Something under the passenger dash (or elsewhere) is intermittently shorted.
3. ECM - The ECM is going bad, but occasionally keeps it together long enough to run
4. BCM - The BCM is going bad, but occasionally keeps it together long enough to run
5. Battery - The battery (2.5 years old) is flaking out, when it sits overnight, causing the gremlins to return.

While it is cheaper for it to be 1, 2 or 3, they don't explain why it would work for long stretches (a full week), but then fail, now, when it sits for 12+ hours.

Sorry for the long post, but, as always, looking for other options and hoping to help future generations that encounter the same problem...As always, I will let you know how the troubleshooting progresses.

[shodog]

I would bet money that it's your battery causing a lot of the issues.

[ae7456t]

Man, I wish you were right, shodog.

For better or for worse, I ended up finding a used ECM, locally, and taking a chance that it could be programmed for my car...Early feedback from the Nissan dealer I tool it to is that they only get a "blank screen", when they try to access the ECM, after installing it. That means that it is either not a compatible model (all the model numbers matched, except the last 4 digits, which I assumed was some sort of serial number), or the new/used one is dead.

Based on what I have seen, I am more convinced that it is a bad ECM...Now the question is whether I go and find an exact model number match, or send my old ECM out to a company like Sia Electronics to have it repaired...Decisions, decisions...

[pedsemdoc]

Agree with Shodog, before throwing a lot of money at your problems, I would get a new battery.
Lots of fellas have posted about strange electrical behavior/gremlins and it ended up just being the battery....good luck and keep us posted about what the solution is.

Craig

[shodog]

Every time I have Electrical gremlins a new battery has fixed it. Recently my i35 had issues. One morning the radio was on full blast and wouldn't turn down or shut off even with the key out of the ignition. I had to disconnect the battery. After reconnecting he radio wouldn't work. Then one morning after a rain, both front windows are down and the sunroof is popped up. I drive it to work a few days later and it wouldn't start in the evening. I replaced the battery and all the problems went away and the radio started working.

Your battery is old, you should start there

[Costee]

Yeah, it's all somewhat complicated. I think I recall that you got the IPDM off ebay. I'm wondering whether all is well with that unit. I know the failing battery causes all sorts of issues in car, but not usually not so much/many at once. It's all right to have the battery changed nonetheless, since it's old, to remove all doubts from that quarter. Again, since the numbers on the ecm you installed matched the old one it is probably bad. The last four digits indicate only the production date of the car. Take for example my car ecm:6H MEC35 870 D1 5524. It means the production date is 24 May 2005.

[ae7456t]

Awesome input, from all...Really appreciate the additional perspectives.

Quick update...Just spoke to the Nissan dealer, and they think we need to go in a different direction. What they neglected to tell me, last night, is that there were "a number of permanent transmission codes" that they found, when they were trying to program the ECM. This would point to some issue in the transmission/TCM and could also be the source of the U1000 code and related issues.

I asked them to start that diagnosis, so we will see where it leads, but it looks like the drama with this transmission continues.

If that is the source of the issues, I am still amazed that it drove for a week, without even the slightest hint of an issue, but I know these things can be sporadic and random.

More info when I have it...

[ae7456t]

***Update***

Costee gets the prize for today...Just heard back from Nissan, and they said they did a continuity check in the IPDM, and there is no continuity between the IPDM and the BCM (looking at the wiring diagram, I don't think there is supposed to be, so I am hoping he meant no connection from the IPDM to the CAN, and by extension, the BCM).

As Costee points out, my IPDM is an eBay special...So, I just got in contact with the seller, and turns out they have another one...They are shipping it out to me, tonight.

Nissan warned me that this could be the first of a many stage process, but at least it is a start...

[ae7456t]

***Another Update***

I just got off the phone with the Nissan dealer, and something doesn't make sense...They want $350 to install and program my replacement (used) IPDM, and even then, there is no guarantee that what ever the issue is will be fixed.

As far as I can tell, and in my past experience, IPDM's do not need to be programmed, and the install is as simple as disconnecting the harnesses, and reconnecting in the new unit, or am I missing something?

I tried to get him to explain it to me, but he was adamant that the IPDM is what gets the signal from the key and sends it to the BCM, and without programming, the key will not work.

$350 just seems insane, and the explanation does not make sense...Please let me know if I am missing something.

[Costee]

I tried to get him to explain it to me, but he was adamant that the IPDM is what gets the signal from the key and sends it to the BCM, and without programming, the key will not work.

$350 just seems insane, and the explanation does not make sense...Please let me know if I am missing something.

Dunno. Keys are reprogrammed when it's a NATS issue (bcm, ecm, steering lock, and I-Key unit). The IPDM comes into play once all NATS components are adjudged correct. Here's from the FSM: "If the Intelligent Key unit judges that the engine start condition is satisfied, it sends the starter request signal via CAN communication to IPDM E/R and turns the starter motor relay ON." Could you ask for the codes they pulled following their diagnoses?

[ae7456t]

Good question, Costee...I will ask them, but they have been very coy about sharing that information.

The recent experience I alluded to was when the transmission shop replaced the original IPDM with the eBay one...They just did the physical swap, no reprogramming, and everything worked perfectly (granted, for a week). It doesn't seem like a NATS issue (or other sync'ing to the BCM/ECM) would wait for a week to materialize, would it?

[Costee]

... It doesn't seem like a NATS issue (or other sync'ing to the BCM/ECM) would wait for a week to materialize, would it?

Lol. No. It's one for all, all for one, all at once.

[ae7456t]

OK...I am not "anti-dealership service", but I am starting to feel as though I am having a failure to communicate with my local Nissan dealer.

This morning, I asked them to just physically install the replacement IPDM (i.e. no programming), to see if that was the easy fix to the electrical gremlins...The Service Guy explained that it would not work, because the used ECM I had asked them to install last week (which they told me couldn't be programmed...gave a "blank screen" on the Consult), was still installed and was "partially programmed" to the car(ECM purgatory???). Different story than I got, last week.

Not wanting to go down that wormhole, I asked them to just reconnect my original ECM, connect the replacement IPDM, push the start button, and let me know what happened. Again, he insisted that it would not work, since the old ECM was removed from the car, and would need to be reprogrammed, along with his insistence that the IPDM needed to be programmed, too.

I called another Infiniti service shop, and they confirmed that IPDM's do not have to be programmed, so that is concern #1. Further, my understanding on ECM "programming" is that it primarily involves writing the VIN# to the unit, so that it syncs with the BCM, so my original ECM should still work (at least as well as it did, before)...Maybe wishful thinking, on my part, but my thinking was, if we have to put all the parts back together this way, anyway, why not try this, before spending the incremental $115 to "program" everything.

That was this morning, and still waiting to hear back from them, after they do the above and "push the button", but confidence is waning, in the meantime...Darn you, electrical gremlins!!!

[Costee]

This morning, I asked them to just physically install the replacement IPDM (i.e. no programming), to see if that was the easy fix to the electrical gremlins...The Service Guy explained that it would not work, because the used ECM I had asked them to install last week (which they told me couldn't be programmed...gave a "blank screen" on the Consult), was still installed and was "partially programmed" to the car(ECM purgatory???). Different story than I got, last week.
I called another Infiniti service shop, and they confirmed that IPDM's do not have to be programmed, so that is concern #1. Further, my understanding on ECM "programming" is that it primarily involves writing the VIN# to the unit, so that it syncs with the BCM, so my original ECM should still work (at least as well as it did, before)...Maybe wishful thinking, on my part, but my thinking was, if we have to put all the parts back together this way, anyway, why not try this, before spending the incremental $115 to "program" everything.

One fact is established: no programming is required if it's merely to install an IPDM.
Programming is required when any of the NATS components is installed, namely, the I-Key unit, BCM, ECM, and the steering lock unit. Programming involves mainly two procedures: initialization, which erases the former key code; and re-insertion of a fresh code as it were. Now when the "new" ecm was installed it inserted it's code and erased the code of the original ecm. If the original ecm is to be installed again, then it would have to be programmed back. VIN writing is not programming, it's just for identification, i.e., if you were to scan the car without inserting your VIN it will be indicating the VIN of the original car from which the ecm was removed. So, that your car requires programming is not because of the IPDM install (as the dealer guy is contending), but because you're bring back the original (or any other) ecm.

[ae7456t]

Wow, Costee...That is some 100%, Grade A, solid help...Many thanks!!! (can I bring my car to you to fix???)

That also makes a ton of sense, and helps clarify my path forward with the dealership. I am still kicking myself for chasing what, now, looks like a red herring in the ECM, but I will get over that if the current setup gets things back on the road.

Thanks, again!!!

[Costee]

Many thanks!!! (can I bring my car to you to fix???

An expensive project, I'm in Africa! But more seriously I'm just a car enthusiast like most guys on here. Let's just say I have the requisite tools to deal with my M.
Wish you luck.

[ae7456t]

At the rate this is going, it may be cheaper to come see you in Africa, Costee!

Latest update...They put in IPDM #3, and "it is worse than the one that we just took out"...They told me that with IPDM #3 plugged in, the car can "see even fewer modules than with IPDM #2".

I have a meeting with the Technician tomorrow morning, but they are pushing me to buy a brand new IPDM, even if I don't buy it from them, just to eliminate that from the troubleshooting. They still think that there are "codes stored in the Transmission Control Module" which is what really scares me...I can suck it up and pay for the new IPDM, but if I then need to buy a new TCM and/or other modules, we quickly go beyond the point of economical repair.

I am a bit confused based on my (limited) knowledge of how the CAN Communication works...If that is the means by which all modules communicate with eachother, when the IPDM can communicate with some modules, and not others, wouldn't that indicate that the IPDM was good, and lead you to believe the modules the IPDM can't communicate with are bad???

I am sure I am missing something, but trying to wrap my head around how this works.

[Costee]

Latest update...They put in IPDM #3, and "it is worse than the one that we just took out"...They told me that with IPDM #3 plugged in, the car can "see even fewer modules than with IPDM #2"
I have a meeting with the Technician tomorrow morning, but they are pushing me to buy a brand new IPDM, even if I don't buy it from them, just to eliminate that from the troubleshooting.

Do I discern suspicion?
It's a non-choice: between the devil and the deep blue sea.

[ae7456t]

So, I had a very candid meeting with the Nissan Service writer and the technician, this morning...In a nut shell, they are apologetic, but really at a loss for what is going on, and in their defense, don't want to continue to burn through my money, which I appreciate.

So, that leaves me a bit stuck, obviously...One confounding issue is that I appear to be in ECM limbo, with the original (and to my knowledge working) ECM #1 removed and ECM #2 only partially programmed. The challenge being, if I have the car towed home so I can trace harnesses, swap IPDM's, etc, will I be able to tell if I find the issue with a limbo ECM installed, or will the ECM being in Limbo always show as a fault, even if I fix the electrical gremlin???

The other option is to have Nissan reprogram ECM #1 back into the car, but I don't get a warm & fuzzy feeling that they will have much success, given the recent history.

Decisions, decisions...

[Costee]

First you must have ECM #1 reprogrammed back. If you want a new IPDM let the dealer fix it. If you still want to try out #2 & #3 IPDM then take the car home.

[EdBwoy]

It takes a lot for these guys to admit something is above them. Kudos for their integrity.

Pardon me if you've mentioned this before, but where are you located?

[ae7456t]

Thanks, EdBwoy...and I agree...I appreciate their honesty on the situation.

I am located in the NW suburbs of Philadelphia.

I am not sure I want to go any further down the path with the Nissan folks, despite their honesty, so looking for independent shops in the area that would have Consult capabilities to help reprogram ECM #1, and maybe confirm whether the IPDM is really the issue.

[EdBwoy]

Ok, I'm also a little too far to offer any direct assistance but I'd have been willing to switch EPDMs with you and help poke around the car if you needed an extra hand.

Independent shop is a good way to go, especially if you give them enough time and they can squeeze you in between other jobs; or a freelancing tech doing it as a side gig (last time I checked the equipment was pretty costly though).

[ae7456t]

You guys are awesome!!! Huge thanks to Costee and EdBwoy for their advice and counsel.

The M35X has officially vacated the Nissan dealer service and is now with (what appears to be) a promising independent, local service shop.

I explained my galloping tale of woe to the manager and the service tech, and they confidently "accepted the challenge". He then remarked that I had half an Infiniti junkyard worth of parts in the car (2 ECM's, 3 IPDM's, etc)...I took that as a compliment!

More to come, as it develops...

[EdBwoy]

You're welcome, hopefully we can be of conclusive help some other time. Please keep us updated.

[ae7456t]

Quick, intermediate update on my electrical gremlins...

I got a call from the independent shop on Friday afternoon...The Service Manager said that they weren't 100% sure that it was the root cause, but they found some bent/misaligned pins in the harness that connects the transmission to the rest of the car. They could recreate the issues that I had seen, and then, when they adjusted that connector, everything seemed to clear up and run as expected.

Needless to say, I am cautiously optimistic with this diagnosis...Not withstanding the multiple wild goose chases that I (and the 2 other service shops that have looked at it) have ventured on, this one makes the most sense. The issues started after the transmission had been replaced, and nothing else that I (or anyone else) has done seems to have stopped the intermittent nature of the lights.

I am just waiting for the independent shop to get a cost/timing for the replacement harness connector from Nissan...anybody in the market for an IPDM/ECM??? I might have a few extra ones!

[Costee]

Glad to hear the story is about coming to a happy ending. Yes, their diagnosis makes sense in view of the recent transmission transplant in the car.
Two things: (I) which ECM is in the car (ii) I'm interested in knowing whether the new shop scanned the car before or alongside their diagnosis. If it was scanned what were the error codes?

[ae7456t]

Good questions, Costee...I will confirm, but when I left them the car, it had ECM #1 connected (the original), and they seemed to think that they would not have to reprogram it (despite the partial programming of ECM #2), for it to work...I will ask them about that, when I ask them about the codes, as well.

[Costee]

when I left them the car, it had ECM #1 connected (the original)

That can only mean the last shop reprogrammed it back into the car...things were certainly topsy-turvy with that shop.

[ae7456t]

***Update***

OK...I think I may be (again), at the end of my transmission/electrical gremlin escapade...

I picked up the car, this afternoon, and, so far, everything looks great. They showed me the bad TCM connector/harness, and there is little doubt that it was not functioning properly...Corrosion/rust throughout and 2 of the 10 pins came completely out of the connector, when the harness was removed.

Here it is in all it's ugly glory...



Frankly, I am surprised it even ran, intermittently with that kind of mess floating around.

Happy to have the car back, and more confident that we have found the root cause of the issue.

Thanks, again, to all that helped through the process...Until the next adventure arrives!!!