How does a 2014 Frontier with a 2.5 liter, 5 speed manual transmission, know when it has been shifted from 4th gear to 5th gear? What tells the BCM or ECU that the truck is in 5th gear? Is there a sensor or switch that tells it?

That's a very interesting question, no one ever broached it to me. The Identifix diagrams don't show any sort of sensor, but they may be incomplete. The system could do it without a sensor by correlating the ABS wheel sensor counts or the VSS with engine RPM. I'll look in ASIST at the shop tomorrow and try to find out.

Ok. Thanks.

And let me explain why I ask.

The cruise control on this truck shuts off at 54 mph. But only in 5th gear.

When in 4th gear the cruise control operates like a normal cruise control. I have set it, say to "on" at 55 mph, and have been able to use the accel button to take it above 80 mph, and it holds the speed and cruises just fine. All the functions one would expect to perform normally, do, but only in 4th gear and below gears. Try to perform the same functions in 5th, and the cruise control turns off the "set" on the gauge cluster at 54 mph but keeps the cruise lamp lit.

I have looked for a speed limiter (this truck is a used truck and may have been an escort truck for highway big loads), talked to the service manager at a Nissan dealer, and posted on another forum, and no one seems to be able to figure this out.

I can drive it and skip from 3rd to 5th and, still, it will only go to 54 mph. What I found interesting in talking to the Nissan service manager is that he talked to his most experienced tech, 38 years, and even the tech cannot answer why it does this. He said that the only the factory service techs can do a deep dive into the ECU, but when they do they are seeing things like information for accidents such as impact speed, steering position, ect. He even said that a tuner type of person could not write code that would affect the program that sets maximum speed.

There are no warning lights, ABS warnings, or any trouble codes I can retrieve with a Foxwell scanner.

I disconnected the neutral/parking switch and the back-up switch on the transmission and that didn't fix it, looked at the brake and clutch pedal switches, all to no result. I have looked for wire harnesses between the accelerator pedal and for after-market "black boxes" under the dash and in the engine bay and have found none.

The only thing that is consistent is the truck somehow knows it is in 5th gear. This is bizarre.

Well, after a pretty exhaustive trip through the ESM, I can find no evidence whatsoever that the ECM has any clue what gear it's in. So I'm pretty sure your vehicle has been tinkered in some way. Under the dash probably won't be the right place to look for hardware, I'd be looking under the shifter boot and around the ABS unit. It's also possible your ECM has been hacked, I'd get it reprogrammed by a Nissan dealer with Nissan firmware so you know it's clean.

I'll take a look around the ABS unit. I did look around the shifter boot for some type of switch that would be activated when the shifter handle is in the 5th gear position but didn't take off the boot; I'll remove it tomorrow and look around it, and at the ABS.

Interesting what you said about the ECM; does it track the gear position, somehow?

Not that the ESM mentions anyplace. On an M/T it doesn't even look like there's a VSS, the speed signal appears to come exclusively from the ABS to both the ECM and Meter. Like I said, the ECM could certainly figure out the gear by interpolating the vehicle speed, engine RPM, and clutch switch position, but if it does that, there's no mention I could find. Mind you, the electrical documentation on the M/T appears to be a redheaded stepchild, so I'm not sure how far I trust it. That's as much as I could find from what little is there.

I took a look around the ABS unit for aftermarket electrical plugs and for wire splices or any tampering and found none; all looks factory. I also removed the rubber weatherboot under the center console trim and found nothing on the floorboard or on top or sides of the transmission; again factory.
I did a search and found that there are companies that do reprogramming on ECU's, and one is Flagship One in Lynbrook, New York. Do you think that an aftermarket programmer, like this one, could have the ability to make the condition that the truck is having?

dmtaurus wrote: ↑

Sun May 02, 2021 1:38 am

I did a search and found that there are companies that do reprogramming on ECU's, and one is Flagship One in Lynbrook, New York. Do you think that an aftermarket programmer, like this one, could have the ability to make the condition that the truck is having?

Yes, absolutely. That's why I suggested getting your ECM reflashed at a dealership.

I'm just wondering, is that an expensive process to do?

dmtaurus wrote: ↑

Sun May 02, 2021 8:01 am

I'm just wondering, is that an expensive process to do?

Nah, half an hour and the laptop does all the work. The charge will vary from dealer to dealer, but any labor charge more than an hour is robbery.

Stopped by the Nissan dealer today. They wanted an hour of time to re-flash the ECU, and that hour was in total $145.00. To me that is too much for a laptop to do all the work while the tech works that hour on another job. I guess I'll call around.

i took the truck to the Nissan dealer today, and it cost $112.00. They ran a scan on it and found no codes. They took it for a test drive and did verify this cruise control condition. The tech was stumped. So, he sent a message to Nissan tech to get help. Several hours later and several back and forth messages between the dealer and Nissan tech center, according to what the the service manager told me, the Nissan tech service could not explain why the truck is doing this. I asked the service manager if he could re-flash the ECU but, according to him, there is no update for the ECU for this particular model so he said it wouldn't do any good to do so. It was unclear to me if they just didn't want to overwrite the existing ECU software or if they thought it would be a waste of time to re-flash. What I told the service manager was that I found it amazing that the Nissan tech center could not figure out this problem. I am still mystified by all this. I did tell the service manager that I had a Ford Taurus and the dealer tech had the rights to re-flash the ECU at the dealership, which they did. Maybe Nissan des not give these rights to their dealer techs. What should I do?

No, the problem is most likely the Consult3+. The way it's set up, if the ECM was reflashed with a different program but whoever did it didn't alter the part number, the C3+ will say "no update available" if the part number is the latest for the application. It won't look at the code, just the p/n. The workaround is to select "program blank ECM" instead of "reprogram", but some guys don't know the trick.

A couple thoughts: Was it ever a commercial truck? If so, perhaps there was something added (piggybacked) to prevent exceeding the speed limit (commercial insurers do this for fleet trucks all the time).

Also, why not just buy a compatible ECU and test it? I replaced my 97 HB ECU last year during the restoration... pretty sure I found it on ebay.

VStar650CL wrote: ↑

Thu May 27, 2021 7:28 pm

No, the problem is most likely the Consult3+. The way it's set up, if the ECM was reflashed with a different program but whoever did it didn't alter the part number, the C3+ will say "no update available" if the part number is the latest for the application. It won't look at the code, just the p/n. The workaround is to select "program blank ECM" instead of "reprogram", but some guys don't know the trick.

So, if I go back to the dealer and ask them to reprogram it as if it was a new ECU then the ECU would start off with a new software upload of the old software program, which should overwrite, totally, the old software and any changes that might have been done in the old software? Can the techs typically do that with the approval of the service manager? It seems to me that they could have tried that. So, you think that out of lack of understanding that the tech didn't know that he had that option?

As a customer I tend to think get a little wary of telling the dealer what to try, but I guess I can try to talk to them again.

I appreciate you thoughts and views since this is your occupation.

AZhitman wrote: ↑

Thu May 27, 2021 10:20 pm

A couple thoughts: Was it ever a commercial truck? If so, perhaps there was something added (piggybacked) to prevent exceeding the speed limit (commercial insurers do this for fleet trucks all the time).

Also, why not just buy a compatible ECU and test it? I replaced my 97 HB ECU last year during the restoration... pretty sure I found it on ebay.

I do believe that it started of life as an escort truck. It was bought from a small used car dealer, who in turn, bought it from the auto auction. The title was clean but IIRC, a business owned it initially and I think that business may have been a trucking/machinery mover over the open road.

I have been all over the truck from the transmission sensors to under the dash and all the pedals, under the hood to the ABS and throttle body, to the wheel speed sensors, the engine speed sensor, and to the removing the rubber boot under the 5-speed console, and there are no aftermarket switches or sensors.

Thus, I tend to think that the ECU was reprogrammed because that would, in my mind, be the fasted and most efficient way to limit speed without paying for labor to install wiring and sensors/switches.

To answer your question, when I got into this I was unsure where this would go. I guess I could try for a used ECU but that seems to me to be somewhat risky with it's own set of problems. So, that is why I tend to think that the ECU in the truck could be erased (or overwritten) and a new software installation could be done.

Thanks.

dmtaurus wrote: ↑

Fri May 28, 2021 3:03 am

So, if I go back to the dealer and ask them to reprogram it as if it was a new ECU then the ECU would start off with a new software upload of the old software program, which should overwrite, totally, the old software and any changes that might have been done in the old software?

Exactly.

dmtaurus wrote: ↑

Fri May 28, 2021 3:03 am

I guess I could try for a used ECU but that seems to me to be somewhat risky with it's own set of problems. So, that is why I tend to think that the ECU in the truck could be erased (or overwritten) and a new software installation could be done.

If it was an automatic I'd say go for that, but finding an M/T ECM that already has the right firmware probably won't be easy.

In finding a used ECU I really think that could turn into a mess real fast.

So, I just emailed the dealer moments ago to see if they would try your earlier answer of reprogramming it like a new, blank ECU; your answer makes so much sense as to why the programmer is not seeing the software code and just seeing the ECU part number! Hopefully they will accept it and get back to me, as I offered to come back to give it a try.

VStar650CL wrote: ↑

Fri May 28, 2021 4:02 am

dmtaurus wrote: ↑

Fri May 28, 2021 3:03 am

So, if I go back to the dealer and ask them to reprogram it as if it was a new ECU then the ECU would start off with a new software upload of the old software program, which should overwrite, totally, the old software and any changes that might have been done in the old software?

Exactly.

dmtaurus wrote: ↑

Fri May 28, 2021 3:03 am

I guess I could try for a used ECU but that seems to me to be somewhat risky with it's own set of problems. So, that is why I tend to think that the ECU in the truck could be erased (or overwritten) and a new software installation could be done.

If it was an automatic I'd say go for that, but finding an M/T ECM that already has the right firmware probably won't be easy.

The dealer just called back and said he talked to the techs and they have not done this procedure on an ECU on a Nissan vehicle. The techs are worried that there might be is a possibility of frying the ECU, and then I would end up having to buy a new one. Do you think that they are being too cautious? Is there a high possibility of frying the ECU? The service manager says if it should fry it that I would be looking at about $1200 for a new one, yet he is willing to try it if I would choose to do, but at my own risk.

Something is goofy with this dealership. Nissan doesn't even sell pre-programmed ECM's anymore, they all come blank. So if they've never performed a blank program procedure, then they haven't sold a new ECM in about 3 years.

You might be right; I didn't get into their experience with programming blank ECU's. So do you that there concern of frying the ECU, that has already been programmed and is being re-flashed, is not really valid? I don't want to end up with a brick if I can avoid that, as you would know.

The only way you can trash an ECM with programming is by equipment failure, if the C3+ crashes in the middle of the procedure. That's exceedingly rare as long as they start with a full charge on the laptop or keep a charger on it. Other than that, they'll need to get a ROM-ID from the Parts Dept and make sure they plug in the correct number. So yes, they can f@%# up if they're completely clueless, but it won't be the program or the process that f@%#s it.

Well, here's the whole story on this problem that's been going on since my son bought the truck several years ago, and the avenues we have tried to fix it; I didn't want to get bogged down in too many rabbit trail details but here goes.

Several years ago my son called into a live Saturday morning radio show called “The Car Show”, out of 760 WJR in Detroit, Mich; AM carries great during the day in the part of the country I live. The guys on the show said to look for aftermarket equipment, because they thought that someone might have put a specific limiter on it that only engages 5th gear. So we looked and found nothing.

Time goes on for about a year. And while driving the thing on the interstate for several hours it was kinda of a pain not to set the CC to the speed limit. So a few days later, I talked to the local Nissan dealer service manager, and as you could predict, they never heard of such a problem; first clueless service manager look that I got. Only response was, “Bring it in and for service fee of $145.00 we can look at that.” His response inspired no confidence.

A few months ago, I was listening to another Saturday morning car fix radio show that originates about 120 miles from me and on the other side of the state. This show has, as a co-host, a local dealer's Nissan service manager, that helps solve callers car problems. I called in and the Nissan guy was totally stumped, and he admitted it over the air. The other co-host is an experienced 40 year GM guy and he tried but said he had no idea. So the Nissan guy was kind enough to take my phone number off the air and told me he would talk to his top tech guy of 38 years on Monday and see what his thoughts were. 3 days later I got a call from the Nissan service manager and he said his tech viewed all of Nissan history and verified with me that there are no trouble codes; all the typical stuff. He said his tech was the go-to guy for the real tough problems but admitted that he did not have a clue given the simplicity of this truck.

Third attempt to fix this was the story related I related to you several days ago with a dealer that is in a much bigger market that I thought would see more of these kinds of problems and know how to fix them, without all the guessing and hesitancy that so many dealer service managers convey. Of course no solid answers from them, just more clueless looks.

So in a search several days ago I found an ECU/BCM reprogramming service called Flagship One in Lynbrook, New York . I called them to see if they might have programmed the ECU based on the VIN and the sticker part number on the ECU. They said that their records don't show anything. But they said that doesn't necessarily mean anything since they not only program customer ECUs, and sell replacement used reprogrammed units, but also do solder board repairs, and when they do these services sometimes they don't have the VINS when they do service work, just the make, model, ect. So for $150.00 and all the back and forth shipping included, they said that they could reprogram the ECU to factory software based on year, make, model, VIN, and it would be a 6~8 day turnaround depending on the work load. If for some reason the ECU doesn't take the software reprogram then they said they won't leave me with a brick; instead, they will send the unit back to me and I could use it in the same state that I sent it in, and they keep the $150.00. If the unit has defect that has to be repaired on the circuit board then it is my choice to have them repair it and the charge goes to $300.00 to fix it plus the $150.00 reprogram fee.

Have you heard of this firm or this type of service being done? Their site says they work with individuals and dealers, and my impression is they seem to be highly specialized and experienced in what they do.

What do you think?

dmtaurus wrote: ↑

Sun May 30, 2021 4:00 am

Have you heard of this firm or this type of service being done? Their site says they work with individuals and dealers, and my impression is they seem to be highly specialized and experienced in what they do.

What do you think?

Sure, they're the same sort of fleet guys who probably reprogrammed it in the first place. Most of them are very reputable and know what they're doing. So if the dealer is incompetent or untrustworthy, I'd say that's an excellent option.

Thanks, I value your advice. I think that is the route I will pursue, and I will let you and the forum know the result.

VStar650CL wrote: ↑

Sun May 30, 2021 7:05 am

Sure, they're the same sort of fleet guys who probably reprogrammed it in the first place. Most of them are very reputable and know what they're doing. So if the dealer is incompetent or untrustworthy, I'd say that's an excellent option.

It's certainly not rocket science. Jim Wolf made a living reprogramming Nissan ECUs. Stillen and several other companies did as well. Hell, our very own Wes Stinson (elwesso) had a business here on the forums (at 19-20 years old?) reprogramming Infiniti Q45 ECUs.

Are they still active in doing this? Are reprogramers listed somewhere on the forum?

Jim Wolf (JWT) and Stillen should be easy to find. Wes has a grownup job now, but you may be able to PM him here.

Tried Stillen but the website looks more like a parts vendor than a reprogrammer. I sent an email to Jim Wolf and will wait for a response.