Push button start not working, no keyfob detected. BCM? [FIXED: iKey unit]

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EniGmA1987
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Push button start not working, no keyfob detected. BCM? [FIXED: iKey unit]

Postby EniGmA1987 » Mon Apr 05, 2021 12:56 pm

So my battery terminal connectors have gotten loose over the years and this past weekend I was replacing them. Anyway, long story short while cutting the OEM negative terminal connector to put a proper lug on it I accidentally touched both positive and negative terminals for a slit second with my tool and caused a short. Seems like it shouldn't do much damage considering the short was between my tool and right at the battery, but after getting the new terminals on and everything tightened up again the car won't start. The car has battery power, all lights work, windows work, doors work, etc. However, when I press on the brake pedal the dash doesn't show the icon it normally does for how to start the car. The push button to start the car does not light up. When I put the key fob in the socket the car does not do a beep like it used to. Basically, everything seems good except nothing relating to starting the car functions. An interesting bit though is that if I leave the key fob in the socket and open the door, the car does beep at me to remind me not to forget the fob and will stop beeping when I take the fob out of the slot with the door open. I did already check all fuses in the car and everything checked out good. The car did function perfectly fine before I replaced the battery terminal connectors.

So my thought is that little short somehow fried the Body Control Module? I know that has to do with controlling the starter and all that. The other thing I was thinking was that may the Intelligent Key Module got fried? I dont entirely know what that unit does other than receive the data for the key fob. I do know it is connected right near the push button to start the car so maybe it also sends power to the button? Could it be a relay somewhere that is fried?

What do you guys think should be the place to start looking?



edit: another odd thing is that the steering wheel is locked up. I was reading up on putting the car into neutral while off to roll it since the car is in my garage and if I have to get it towed I need to be able to get it down the driveway. The information said that when I get it into neutral with the car off the steering wheel lock should release as long as there is battery power. Well I know battery power is fine, and I put it into neutral, but the steering wheel stays locked. Would the BCM be what tells the lock to disengage and so maybe if the BCM is fried that is why the steering stays locked?


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VStar650CL
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2004 Nissan Altima 2.5 S

Re: Car wont start, not pushbutton light up, no keyfob detected. BCM?

Postby VStar650CL » Mon Apr 05, 2021 1:53 pm

Sparky shorts and reverse jumps often blow fuses, the doghouse and I-key Unit are both powered off fuse 22 in the inside fuse block. The steering lock is powered by the I-key Unit, so that would be dead too. Use a test light to check so you can also identify if a fuse is cold on both sides. If fuse 22 shows no power on either side, check the fusible links at the battery and in the fuse/relay box, those are closest to the short and most likely to pop. If they all check good, then it's possible you cooked something.

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VStar650CL
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Re: Car wont start, not pushbutton light up, no keyfob detected. BCM?

Postby VStar650CL » Mon Apr 05, 2021 2:08 pm

06 M45 Fusebox.png

EniGmA1987
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Re: Car wont start, not pushbutton light up, no keyfob detected. BCM?

Postby EniGmA1987 » Tue Apr 06, 2021 7:24 am

Ya I checked the fuses at the start and they were all good. I went and replaced almost every fuse and relay in the car last night since I was able to get them all for about $20. Still no luck, it has the same behavior. I think I will start working on getting the BCM out of the car and see if I can find a part number match on ebay for cheap. Looks like a lot of used ones where for around $40~ Hopefully Ill get lucky.
Only problem if the BCM gets replaced is my keys will no longer work. I am hoping that I will at least be able to see power again which would let me know I was on the right track, but Ill have to try and find a locksmith who can reprogram the keys for me and pair them with the new BCM.

Any other ideas besides the BCM or i-key module at this point?

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VStar650CL
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2004 Nissan Altima 2.5 S

Re: Car wont start, not pushbutton light up, no keyfob detected. BCM?

Postby VStar650CL » Tue Apr 06, 2021 8:37 am

Since the I-Key Unit powers the doghouse, I'd say it's more likely that's the culprit than the BCM.

EniGmA1987
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Re: Car wont start, not pushbutton light up, no keyfob detected. BCM?

Postby EniGmA1987 » Tue Apr 06, 2021 9:40 am

I was looking around trying to find the part number for the i-key unit and came across this thread here from a few years ago:
2007-m35-won-t-start-t613922.html#p6733373
2007-m35-won-t-start-t613922.html#p6735348
It does sound like my symptoms as well so I think you are right, I should look at the i-key unit first instead of BCM. Unfortunate as that unit is not nearly as common as used BCMs and is much more expensive. Thanks for your help putting me onto this thrack first

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VStar650CL
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Re: Car wont start, not pushbutton light up, no keyfob detected. BCM?

Postby VStar650CL » Tue Apr 06, 2021 3:57 pm

You're most welcome, hope it works out okay. Sometimes this kind of stuff is a bad guessing game. :frown:

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Re: Car wont start, not pushbutton light up, no keyfob detected. BCM?

Postby EdBwoy » Wed Apr 07, 2021 12:50 am

You said you replaced a lot of the fuses in the car, but I would like to clarify does that mean inside the cabin or car in general?

I ask because there are some fuses and fusible links in the engine bay that I would be interested in checking first. These are located in front of the battery, and while at it, you might as well visit the IPDM.

I have a high level guide, but apparently I have never gotten around to uploading the labels of each of those fuses.
major-fuses-relays-and-modules-and-thei ... l#p6780240

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VStar650CL
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Re: Car wont start, not pushbutton light up, no keyfob detected. BCM?

Postby VStar650CL » Wed Apr 07, 2021 4:25 am

EdBwoy wrote:
Wed Apr 07, 2021 12:50 am
You said you replaced a lot of the fuses in the car, but I would like to clarify does that mean inside the cabin or car in general?

I ask because there are some fuses and fusible links in the engine bay that I would be interested in checking first. These are located in front of the battery, and while at it, you might as well visit the IPDM.

I have a high level guide, but apparently I have never gotten around to uploading the labels of each of those fuses.
major-fuses-relays-and-modules-and-thei ... l#p6780240
True, depends what "checked" means. The only right way to check fuses is to probe both sides with a test light, if it lights on only one side then it's blown. If it lights on neither side then it has no power, which tells you something is wrong upstream like a fusible link or open wire. If the OP only pulled and checked the fuses visually, then the links will also need checking.

EniGmA1987
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Re: Car wont start, not pushbutton light up, no keyfob detected. BCM?

Postby EniGmA1987 » Wed Apr 07, 2021 7:49 am

EdBwoy wrote:
Wed Apr 07, 2021 12:50 am
You said you replaced a lot of the fuses in the car, but I would like to clarify does that mean inside the cabin or car in general?

I ask because there are some fuses and fusible links in the engine bay that I would be interested in checking first. These are located in front of the battery, and while at it, you might as well visit the IPDM.

I have a high level guide, but apparently I have never gotten around to uploading the labels of each of those fuses.
major-fuses-relays-and-modules-and-thei ... l#p6780240
Once I have gotten the battery hooked back up at the start of this whole thing and saw the car was not starting and had the dead behavior of the pushbutton, the first step I took was to check fuses. I looked up a diagram with label of what each fuse in the cabin was for and checked the 3 fuses that had anything to do with the car starting up. I pulled the fuses out one at a time, visually inspected and then tested with a multimeter and got a nice 0 Ohm reading. When those 3 checked good, I started back at the beginning and checked every fuse starting with #1 inside the cabin one at a time with a visual check and multimeter. This included a double check on the 3 I had already done first, which was fuse 22, then fuse 21, then fuse 1.
With the cabin all checking out good, I moved to the engine bay. I did a check on every fuse in both fuse boxes located there. The "weird looking fuses" that are shaped funny I also checked visually and with a multimeter.
When every fuse in the car checked out good with a 0 Ohm reading, I started to get worried that I had fried something important and came to post here about my thoughts on it being either the BCM or i-key unit.
edit: I used this site to find a description of the fuses and their location: https://fuse-box.info/infiniti/infiniti ... and-relays


I did not know specifically what the IPDM was so I looked it up just now and it appears this is it?
https://partsbeast.com/Infiniti/M35-Par ... Box/306888
If that is correct, I checked all the fuses in that unit. I did not know it was a specific controller, I just thought it was a board with fuses and routed power to the relays.



I looked on Amazon and found a pack of fuses for about $10 and a 5 pack of relays for around $5. So I bought all that because it is prudent to have some automotive fuses around anyway for issues that arise. Just for good measure, I replaced every standard fuse in the car. By that I mean every "mini low profile fuse" in both the cabin fuse box, the engine bay fuse box, and the other engine bay fuse box which is apparently the IPDM. The only fuses I did not replace are those special shaped ones in the long skinny fuse box.
I also replaced all the 4 pin relays in the IPDM just for good measure as I came across something in my searches that said one of them was related to the starter and another the ignition. I also read that the ECM relay ties into those systems but I do not know how correct that is. So with 3 of those relays being involved in the system having trouble I decided I should replace them just to check. I figured with the relays being 15 years old and a pack of replacements was only $5 I might as well replace all of them for good measure. I know at work we replace relays about once a year so they do wear out. granted the machines at my work run much more time than the ones in the car, but still after 15 years they have to be getting old.
VStar650CL wrote:
Wed Apr 07, 2021 4:25 am
True, depends what "checked" means. The only right way to check fuses is to probe both sides with a test light, if it lights on only one side then it's blown. If it lights on neither side then it has no power, which tells you something is wrong upstream like a fusible link or open wire. If the OP only pulled and checked the fuses visually, then the links will also need checking.
I did not check yet with a test light probe as I did not have one yet. I bought one to have on hand and it should be here today so I can check after work. I believe power to the fuses is fine though as all other electrical system in the car work fine.



I will post pictures of the 3 fuse boxes when I get off work so you can see all the fuses and which relays I replaced.

At this point I believe VStar650CL's opinion is correct, it is most likely the i-key unit.

edit again: I did not check the fusible link block on the positive side of the battery other than a visual inspection of them. I believed with it visually looking ok, not hearing any loud pop from one of those blowing, and with every other electrical system in the car being fine that those main links were ok.

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Re: Car wont start, not pushbutton light up, no keyfob detected. BCM?

Postby VStar650CL » Wed Apr 07, 2021 8:28 am

EniGmA1987 wrote:
Wed Apr 07, 2021 7:49 am
I did not check yet with a test light probe as I did not have one yet. I bought one to have on hand and it should be here today so I can check after work. I believe power to the fuses is fine though as all other electrical system in the car work fine.

edit again: I did not check the fusible link block on the positive side of the battery other than a visual inspection of them. I believed with it visually looking ok, not hearing any loud pop from one of those blowing, and with every other electrical system in the car being fine that those main links were ok.
Using a voltmeter and then ohming is equivalent to using a test lamp. The advantage to a bulb-type test light is that it tells you immediately that the circuit can carry power, since the bulb itself consumes some. For the fusible links, it's very rare for one to blow without highly-visible evidence, so your visual inspection was fine.

EniGmA1987
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Re: Car wont start, not pushbutton light up, no keyfob detected. BCM?

Postby EniGmA1987 » Wed Apr 07, 2021 6:13 pm

Here are the pictures of the fuse boxes in my car with the fuses and relays I replaced:

In cabin fuse box:
Fuse Box 1.jpg


IPDM "fuse box"
IPDM.jpg
According to my search, the far bottom relay is the ignition relay. The one just above it to the left is the starter relay. The very top left one goes to the ECM/ECU among other things.



Fuse box "3" in the vehicle:
Fuse Box 3.jpg
I didnt replace the square and weird shape fuses as I did not know what they were called to search for them. I have since found that apparently the square ones are "J Case". Whether they are low profile or standard I am not sure. I have since found the weird shape ones are custom Cooper Bussman fuses for Nissan that are "3 pole". Meaning they have 1 input side and 3 fused output sides with a high amp and two lower amp poles. Why go through the trouble just to take up more space than using normal fuses IDK. The models of the two weird custom fuses are: Bussman MPF-533X (stands for multi-pole fuse 50A, 30A, 30A) and Bussman MPF-433X
Hopefully anyone who ever needs those fuses will find this post with those model numbers. They are about $15 on Amazon, and I would bet probably double or triple from a dealer.

EniGmA1987
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Re: Car wont start, not pushbutton light up, no keyfob detected. BCM?

Postby EniGmA1987 » Sat Apr 10, 2021 3:47 pm

I got a used i-key module for a decent price in last night and installed it into the car today. My car has power again! Looks like the problem is solved. The only thing left to do now is either find a mobile locksmith who can program the key fobs to the new i-key unit or tow the car to a dealer to have them do it. Hopefully a locksmith around me is able since the dealer is a lot of money.
Thank you for all the help VStar650CL and EdBwoy. For steering me to the ikey first and for helping me find the ikey unit location.

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Re: Car wont start, not pushbutton light up, no keyfob detected. BCM?

Postby VStar650CL » Sat Apr 10, 2021 4:30 pm

You're most welcome. Hopefully you can find a 'smith for the repro and get it done in the driveway, for an '06 there's a good chance of that. Happy motoring!


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