Good evening everyone...I'm a new member with a new to me Nissan Sentra that I'm trying to fix up. After reviewing different forums, the answers I saw that were provided on this one were to the point and weren't farfetched or off topic, so hats off to you guys. I recently purchased this vehicle as a project and asked the previous owner what the deal was with the car.

The little information they gave me is as follows...their daughter was using it and when she arrived home it died. Apparently the negative battery cable was loose. They tightened it and the car wouldn't start. So they bought a new battery and it wouldn't start. It would crank, but not start. So they had it towed to a couple of different mechanics and they couldn't get it running. They called a shadetree mobile mechanic and no dice either. What they were able to find out was the immobilizer was "probably" the culprit.

The car has about 137,000 miles and is the 2.0. It has the Intelligent FOB (4 button) set up and the barrel or door knob type ignition switch. Battery is fully charged, everything electrically works (i.e. radio, lights, blinkers, wipers, etc.).

So the previous owner decided to buy a new steering column with all the sensors on it and it still wouldn't work. The wiring underneath was a mess.

So it sits for 5 months and here I come. I can see the immobilizer light will not go out when cranking. Both the original column and new"ish" column (from the salvage yard) only have one key. The little key that goes inside the Intelligent FOB. So I have it towed to my house and spend a day putting the original column back in. I figure let's start from scratch and have the original components back where they were.

The car had 27 codes and after putting everything back together and clearing them, I'm down to 4. The two in the title and two for an airbag circuit.

I've done the 5 sec. on and 10 sec. off procedure. I've done the panic button for 5 second potential reset, taken the negative battery terminal off for 10 min., a couple of hours and even overnight. I've read dozens of threads and many of them are conflicting. I've checked all the fuses, touched the battery terminals together, unclipped and reinserted the plugs to the ECM and TCM (all look good). Locked the car with the FOB, unlocked the car with the little key and tried starting it with it as well.

So what I think I've boiled it down to is having a mobile locksmith stop by and try to program me a new key or take it to a Nissan dealer. My two pointed question is, is there anything I may have missed and if not, would a reprogrammed key get this car started? I'm thinking of calling a mobile locksmith (that I've used in the past) tomorrow morning (as it's 11:40PM here) and see if they can do this.

All help or feedback is greatly appreciated. I hope everyone is doing well in times like we're in now.

*********UPDATE*************

Mobile locksmith came out and indicated that he could read the ECM, but the ECM was not responding. So its still not repaired.

He couldn't clear the codes of P1610 and P1614 because the command would not go through. He wasn't sure what that meant and speculated that there may be something wrong with the ECM. So I'm trying to find some direction if I should buy another ECM (to which I would need to have it programmed I'm sure) or try and trace out all the wiring under the column to see if one of the wires is not being energized. It would be nice to have a wiring diagram with color information.

I'm just hoping someone can point me in a particular direction on where to start or look for. TIA!

**********NEW UPDATE*************

In May I purchased a BCM from a Sentra at a salvage yard. It was a BCM from a car that had a mechanical ignition switch and no intelligent entry. This was my mistake as I was trying to see if the BCM was indeed specific for every car. Without input from my question back in April (see above) I had to start throwing parts at the vehicle. However I'll outline what I came across in hopes that it may help someone else.

A BCM is different for a car with a mechanical key setup than for a car with an intelligent key. This recently acquired salvage yard BCM allowed the car to start with the hidden mechanical key in the original intelligent FOB. That was a surprise, however I couldn't get the FOB to be programmed to the car or have the car start with the FOB in my pocket. An automotive locksmith figured this out. That's why I'm thinking this BCM would not allow the intelligent key to be programmed in to it because it wasn't part of a car that had this.

So I found a Sentra with an intelligent key setup at a different salvage yard and I bought the steering column, BCM, ECM, and key (there was no FOB with the car). The car still would not start with just changing out the BCM from the intelligent junked car and leaving the original ECM. However when I put in the ECM that was paired with that BCM, the car started with the matching mechanical key. No other keys would now work. Even though I still couldn't program the FOB myself I had an auto locksmith do the job and now the car starts with the FOB in my pocket and the intelligent entry works.

So the fix is to get the paired ECM & BCM if ever coming across this scenario. An automotive locksmith can get just about any FOB to program to the car if the mechanical transponder key works/starts the car. The NATS reader on the steering column is not a factor. It just sends a pulse to the BCM that then looks to the ECM for a match and if good, the car starts.

Final reminder, get all the items that may work with the mechanical key so the car is all keyed the same.

Hello. Thanks for posting this. I know it's an old thread but I'm trying to help someone with the same issue. It's a 2007 Nissan Sentra 2.0 with the older style 'mechanical' key, not the fancy FOB style.

She disconnected battery during a routine maintenance and now the car isn't firing up but is cranking over and then I found out what was going on and offered to help. The car cranks over but won't fire up. The first thing I did was take battery out and let it charge overnight. This was a new battery though and I did it because I could tell it was getting low from the previous crank attempts.

I put the battery in and went through all of the connections that she touched, checked fuses, tightened all battery cable connections, etc. When it still didn't start I noticed when I turned the key on that their is a CAR + KEY indicator lit up solid. Immediately I thought, it isn't recognizing the key or something. Sure enough research indicates this vehicle is in a locked mode and to clear it requires 5 sec on, 10 sec off x 2 with a registered key. I tried this and no success. Tried pressing the key fob unlock/lock/panic, etc like the internet suggests. Tried a whole bunch more than I can even remember to get it to clear. Nothing!

A # of days went by and was able to get a mobile locksmith out. He connected to the car and there were 3 codes: U1000, P1610, P1611, and a Transmission valve body code common to this year P0894 that shouldn't have any impact. These first 3 errors indicate CAN Bus issue, Lock Mode, IMMU Discord (whatever that means) respectively. He could not program any keys, it wouldn't even communicate to his programming device. Since she has only 1 key I couldn't try another but these keys don't even have a battery in them, just the little coil device. These 3 codes in unison make me think there is a faulty module and it's disrupting communication issues on the CAN bus but is it a different module or the IMMU (Immobilizer) ? My OBD II ELM327 based device didn't even show those 3 codes. I also think after 5 attempts of trying to start the car it locked. Right now I have the battery disconnected for over a day and I'm going to go watch to see if car is in LOCK mode right away or if it takes 5 key attempts first.

My questions are: Does anyone know what I can check for the U1000. Does the IMMU (immobilizer) unit itself talk on the CAN Bus. It's my understanding from videos+diagrams that the IMMU reads the key, sends it to the BCM, and the BCM actually triggers the key+car NATS indicator. Any other suggestions? What kind of devices do I need to troubleshoot the CAN bus? Could there be a fuse blown that I missed somewhere, or fusible link? If the BCM needs to be replaced, who can do program it. It looks like it's in the dash behind the cluster on the right according to a video I saw (a good bit of stuff would have to be removed to access it).

P.S. To the Op if you ever see this thread, I want to thank you personally for putting your experience out there and following up with updates. Can you buy a BCM from a salvage car (does it come with the key? lol ) and just plug it in? Sounds like it needs to be programmed if she has a bad BCM and we end up having to replace it.


P.S.S. All of this over a battery being disconnected! I feel so bad for her. She has no car and kids.

Hey 07Sentra2.0...I received a notification of your post. I can offer the little I know to the issue you’re looking at.

When I first received the Sentra it wouldn’t start after the car battery was changed out by the previous owner. Weird the same is happening to you. The BCM was toast for some reason. I could lock the car, unlock it, and pop the trunk, but it just wouldn’t start. It had the red car and key on the dash IIRC.

The scrapyard BCM that was in a car with a mechanical key ignition didn’t need to be programmed when I installed it. It just wouldn’t accept the extras my car had. Also I was lucky to find a car with its key in it.

You are correct as to it’s location. I learned to put everything loosely back to make sure the car started before bolting everything back into place.

One thing I also learned was the car wouldn’t start immediately after changing parts. It needed to recognize over a period of a couple minutes of what was just done. I remember putting the key in and having the NATS lit up. I did the cycling of the key and at one point either the red key or car didn’t come on anymore. I think I left the ignition in the accessory position for awhile. That’s when it started.

As far as CAN bus issues, my limited knowledge says if you can at least see all the modules on a scanner, then the CAN wiring is good. A low voltage situation can have all sorts of codes pop up from what I have seen. Bad grounds too.

Hope that helps. Still if you get the BCM from a salvage yard and there is a key in the car, snag that and the ECM. Swap the BCM and see if it starts and hopefully you can return the ECM. If it doesn’t swap the ECM.

@07Sentra2.0 since you have a P1611 (not P1614) as the OP, the culprit is most likely the ECM.

07Sentra2.0 wrote: ↑

Fri May 28, 2021 10:39 am

P.S.S. All of this over a battery being disconnected!

The battery was probably improperly disconnected, causing a spark that damaged the ECM. The U1000, I think, is the result of the spark. The code may be deleted, but the P1611 would have to be resolved by a replacement ECM.

Costee wrote: ↑

Fri May 28, 2021 12:17 pm

The battery was probably improperly disconnected, causing a spark that damaged the ECM. The U1000, I think, is the result of the spark. The code may be deleted, but the P1611 would have to be resolved by a replacement ECM.

Yep, people have a tendency to think the hot terminal needs to be disconnected and often make destructive sparks doing it. For everyone reading, negative comes off first and goes back on last, always. If you're simply disconnecting to do work, leave the positive alone, the car has no voltage if it has no ground. Even if you're replacing the positive lug, disconnecting the negative first will prevent sparks at the positive when you loosen it. Negative terminals spark minimally or not at all, and the sparks they do make have far less total energy than sparks at the hot post. So they won't harm your electronics like sparks at the positive. Negative first, remember it.

SadSentra wrote: ↑

Fri May 28, 2021 11:21 am

Hey 07Sentra2.0...I received a notification of your post. I can offer the little I know to the issue you’re looking at.

When I first received the Sentra it wouldn’t start after the car battery was changed out by the previous owner. Weird the same is happening to you. The BCM was toast for some reason. I could lock the car, unlock it, and pop the trunk, but it just wouldn’t start. It had the red car and key on the dash IIRC.

The scrapyard BCM that was in a car with a mechanical key ignition didn’t need to be programmed when I installed it. It just wouldn’t accept the extras my car had. Also I was lucky to find a car with its key in it.

You are correct as to it’s location. I learned to put everything loosely back to make sure the car started before bolting everything back into place.

One thing I also learned was the car wouldn’t start immediately after changing parts. It needed to recognize over a period of a couple minutes of what was just done. I remember putting the key in and having the NATS lit up. I did the cycling of the key and at one point either the red key or car didn’t come on anymore. I think I left the ignition in the accessory position for awhile. That’s when it started.

As far as CAN bus issues, my limited knowledge says if you can at least see all the modules on a scanner, then the CAN wiring is good. A low voltage situation can have all sorts of codes pop up from what I have seen. Bad grounds too.

Hope that helps. Still if you get the BCM from a salvage yard and there is a key in the car, snag that and the ECM. Swap the BCM and see if it starts and hopefully you can return the ECM. If it doesn’t swap the ECM.

I was really hoping you would get a notification and reply. Thank you!! How the heck would a junkyard key work in the original cylinder lol ? So you're saying I can just swap in a new BCM from a junkyard and it doesn't need to be married to the ECM or anything?

As far as her removing the positive side that is not what happened. She had actually followed a Haynes manual to do some work and disconnected the negative, reconnected it, and then it wouldn't start up anymore but did crank. Then I got involved and we got this far. In addition the locksmith reset all of the codes and only the ones I mentioned in first post are the ones that came right back so unless U1000 code is a permanent code and caused by battery sparks (is it?) that can't be the cause because he reset and read the codes again.

Now today I went there since the battery was disconnected for 24 hours, connected negative terminal tightly to battery. Turned key on and same crap. NATS light lit solid immediately. I tried the reset procedure to unlock it as well.. no dice. This tells me it's not locking after the 5 failed tries but locking immediately for some reason.

Costee wrote: ↑

Fri May 28, 2021 12:17 pm

07Sentra2.0 wrote: ↑

Fri May 28, 2021 10:39 am

P.S.S. All of this over a battery being disconnected!

The battery was probably improperly disconnected, causing a spark that damaged the ECM. The U1000, I think, is the result of the spark. The code may be deleted, but the P1611 would have to be resolved by a replacement ECM.

What makes a P1611 mean ECM replacement over say the BCM or IMMU? Can you explain this.

The locksmith cleared all codes then cycled key and pulled them again and the 4 I mentioned are the only ones. U1000 is permanent or something?

07Sentra2.0 wrote: ↑

Fri May 28, 2021 10:25 pm

Costee wrote: ↑

Fri May 28, 2021 12:17 pm

The battery was probably improperly disconnected, causing a spark that damaged the ECM. The U1000, I think, is the result of the spark. The code may be deleted, but the P1611 would have to be resolved by a replacement ECM.

What makes a P1611 mean ECM replacement over say the BCM or IMMU? Can you explain this.

The locksmith cleared all codes then cycled key and pulled them again and the 4 I mentioned are the only ones. U1000 is permanent or something?

The FSM indicates the ECM when there's a P1611 error code. (The FSM can be downloaded from this site). The BCM is the IMMU (immobilizer unit).

07Sentra2.0 wrote: ↑

Fri May 28, 2021 10:05 pm

As far as her removing the positive side that is not what happened. She had actually followed a Haynes manual to do some work and disconnected the negative, reconnected it, and then it wouldn't start up anymore but did crank.

So the story is beyond mere battery disconnection, there was some work done. The ECM seemed to have been at the receiving end of it. Again, we know these components can sometimes act weird, the ECM could just have passed out for some unaccountable reason.

Since it still communicates, it's likely the ECM has committed hara kiri. For reasons known only to some programmer in Hitachi's basement, on all the older IMMU-only vehicles (no BCM), you get 7 starts after the key reads bad, then another 7 cranks with a bad read, then the ECM kills itself. The P1610 lockout will never clear after that occurs, no matter what you do.

07Sentra2.0 wrote: ↑

Fri May 28, 2021 10:39 am

A # of days went by and was able to get a mobile locksmith out. He connected to the car and there were 3 codes: U1000, P1610, P1611, and a Transmission valve body code common to this year P0894 that shouldn't have any impact.

By way of slight digression, P0894 does not apply to this vehicle or even to the Nissan make generally. Would that be a typographical error?

VStar650CL wrote: ↑

Sat May 29, 2021 4:07 am

Since it still communicates, it's likely the ECM has committed hara kiri. For reasons known only to some programmer in Hitachi's basement, on all the older IMMU-only vehicles (no BCM), you get 7 starts after the key reads bad, then another 7 cranks with a bad read, then the ECM kills itself. The P1610 lockout will never clear after that occurs, no matter what you do.

This one has a BCM though and it's right behind the cluster/vent.

07Sentra2.0 wrote: ↑

Mon May 31, 2021 7:34 am

This one has a BCM though and it's right behind the cluster/vent.

They later ones do the hara kiri thing too, but if there's anything like the 7/7 schedule on the earlier ones I've never figured out what it is. If you have a P1610 that won't clear, it's still most likely a suicidal ECM.

Costee wrote: ↑

Sat May 29, 2021 7:11 am

07Sentra2.0 wrote: ↑

Fri May 28, 2021 10:39 am

A # of days went by and was able to get a mobile locksmith out. He connected to the car and there were 3 codes: U1000, P1610, P1611, and a Transmission valve body code common to this year P0894 that shouldn't have any impact.

By way of slight digression, P0894 does not apply to this vehicle or even to the Nissan make generally. Would that be a typographical error?

More like a memory error on my part, sorry. Was trying to type that out quick during my lunch break at home. It's P0840 I believe. I wasn't focused on that one since I had already known about it by scanning with my own OBDII and had looked up all the info on it including TSBs etc. If I can get it started I will help her address that one next.

------------------------------

Latest update on this is I purchased a small (cheap) immobilizer diagnostic pickup device that is only meant to be used on vehicles like Mercedes, BMWs, etc. It obviously didn't work on my Ford, her Nissan , etc. so I modified the circuit (I'm a PC and electronics nerd) and tested on my Ford and it worked! Ford sends (2) pulses when key is turned on. Her Nissan sent (1) pulse when key is turned on. This indicates to me the immobilizer antenna/device located in the steering column/around key cylinder is good. Can anyone validate that Nissan sends only 1 pulse to read the key?

Also I left the battery disconnected for 24 hours to attempt to reset the 'Lock' mode P1610 and connected the negative back securely, put her key in, turned it ON and the security indicator (car with key in it) came on immediately! At this point I'm leading to module failure of some sort like you guys are saying.

Following the service manual (thanks to person who told me about that) if we can't reinitialize the system with key programming, the issue is ECM according to the P1611 steps. I know this was mentioned earlier, I'm just recapping. So I will get a locksmith out to try to program keys again, if it doesn't work then should I buy a junkyard ECM to try? Perhaps I can get an ECM/BCM together, then get the locksmith to program new keys?

07Sentra2.0 wrote: ↑

Mon May 31, 2021 8:03 am

Ford sends (2) pulses when key is turned on. Her Nissan sent (1) pulse when key is turned on. This indicates to me the immobilizer antenna/device located in the steering column/around key cylinder is good. Can anyone validate that Nissan sends only 1 pulse to read the key?

Also I left the battery disconnected for 24 hours to attempt to reset the 'Lock' mode P1610 and connected the negative back securely, put her key in, turned it ON and the security indicator (car with key in it) came on immediately! At this point I'm leading to module failure of some sort like you guys are saying.

Following the service manual (thanks to person who told me about that) if we can't reinitialize the system with key programming, the issue is ECM according to the P1611 steps. I know this was mentioned earlier, I'm just recapping. So I will get a locksmith out to try to program keys again, if it doesn't work then should I buy a junkyard ECM to try? Perhaps I can get an ECM/BCM together, then get the locksmith to program new keys?

Nissan IMMU's generally only broadcast one comm packet to the key. It's a serial communication and not a pulse, but it will look like a pulse to a voltmeter.

JY or eBay ECM's are usually fine, but don't play with the ignition before the key is programmed or it's the same deal, you're risking hara kiri by your replacement ECM. Get it programmed as soon as you install it.

Thank you all for your replies! VStar650CL since this one has a BCM are you sure the self destruction is a thing with this 2007 ECM ?

Hara kiri is a thing with all Nissan ECM's with NATS/NVIS, except I-keys.

I was able to buy an ECM. To make the new one work what needs to be done.. just program the keys?

Thanks in advance!

07Sentra2.0 wrote: ↑

Thu Jun 03, 2021 6:58 pm

I was able to buy an ECM. To make the new one work what needs to be done.. just program the keys?

If it has the right main programming then yes, just program the keys. The car will probably start even if the firmware isn't exact, but you might want to have the dealer check the part number to make sure it's a correct version for your particular engine and trim.

VStar650CL wrote: ↑

Thu Jun 03, 2021 7:05 pm

07Sentra2.0 wrote: ↑

Thu Jun 03, 2021 6:58 pm

I was able to buy an ECM. To make the new one work what needs to be done.. just program the keys?

If it has the right main programming then yes, just program the keys. The car will probably start even if the firmware isn't exact, but you might want to have the dealer check the part number to make sure it's a correct version for your particular engine and trim.

Thanks bro. The part # was identical. Hoping it works. I'm just trying to help!

The hardware part number and the firmware part number are two different things. Nissan loads different firmware into the same hardware for different applications. For instance, an AWD and FWD Rogue or Murano have hardware-identical ECM's with the same Hitachi p/n on the outside, but they have slightly different firmware for the different configuration.

VStar650CL wrote: ↑

Thu Jun 03, 2021 8:37 pm

The hardware part number and the firmware part number are two different things. Nissan loads different firmware into the same hardware for different applications. For instance, an AWD and FWD Rogue or Murano have hardware-identical ECM's with the same Hitachi p/n on the outside, but they have slightly different firmware for the different configuration.

Makes sense. So it should be OK since it came from the same car right?

Also.. when the locksmith came out and tried to program it wouldn't communicate to program the keys but did fine for pulling codes. Why do you suppose this was the case?

Why couldn't I pull codes like the U1000, P1610, P1611 with my regular OBDII scanner? Is this nissan specific codes or something?

07Sentra2.0 wrote: ↑

Fri Jun 04, 2021 10:49 am

Why couldn't I pull codes like the U1000, P1610, P1611 with my regular OBDII scanner? Is this nissan specific codes or something?

P1610 and P1611 are specific security codes, so a cheap generic scanner either won't see them or will give you a ?whatwuzzat? The U1000 is standard fare, so if your scanner didn't see it I don't know why.

So I replaced the ECM and only turned the key on once to see what the security indicator light would do. It lit solidly just like with the other ECM. Is this supposed to be the case?

The next step is get the locksmith out to see if he can program it all and hope it works lol

The new ECM has to be key-programmed, as do any and all ECM's on NATS/NVIS-equipped vehicles. No offense, I appreciate your curiosity, but with a used ECM, turning the key even once without being ready to program a key was foolish.

The ecm is key programmed and it starts. Prob is it's misfiring and has no power. Code is multiple cyl misfire. Is there some initialization I have to do? I'm considering putting the original ecm back in and seeing if I can have the same luck with key programming since it was successful.

It started with a bad miss then seemed to clear some but not fully. It has no power. Same exact behavior as if it's missing on one cylinder and that cyl is dragging the accel down. It's a dead miss and at the speed of one. Not sure why its multiple cyl but it was worse till it ran for 30 sec so maybe I need to run it longer?

There's no initialization for anything to do with the ignition, but you should do an Idle Air Volume Learn and a Closed Throttle Position Learn. IAVL matches the MAF to the ECM, so not doing it can cause all kinds of issues. Is it throwing any codes?