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no start/computer modual questions

6K views 14 replies 3 participants last post by  DatMan 
#1 ·
I am new to the forum and was just gifted an 04 fx35, with 97k miles, that is in texas (i am in washington state) the car is having the typical starting issue where it cranks but wont fire up. from what i understand the car had hail damage but was repaired and apparently did get some water inside. because of this i plan on replacing the a/c amplifier(this sounds like a common issue), the bcm(door locks and trunk dont work but seats and other electronics do) and the ecm as these seem to be the culprits when reading through other threads.
i also plan on replacing the crank sensor, cam sensor, and spark plugs. can any one think of any other electronics that should be replaced or be the culprit? i want to get all my ducks in a row before i fly to texas to fix it as i dont wanted to get stranded on a 2000 mile road trip home.

now for the second part of my post:
when i search on ebay for the ecm and bcm i see alot that say "for 03,04,05,06" with no part number, but when i did a little more research it looks like each year has its own part number. i called a local infiniti parts department and they told me that both the ecm and bcm are year specific. i was told i need the ecm part no. 23710-cg700. my fx is rwd without active cruise control so i know i would need one specific to that but has anyone tried using an ecu or bcm from a different year?

i can get the part through infinit but its about $200 dolars more than on ebay and i would rather not spend $350 if the part dosnt even need to be replaced but i am prepared to bite the bullet if need be.

any advice would be most helpful.
 
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#2 ·
**UPDATE**
I just had a friend start the car by putting it in neutral. not sure if that bypassed any of the computers or ac amp to start it or why it would start in neutral instead of park. transmission computer maybe? or transmission safety lock out over ride. my friend is going to hook up a scanner next week to see if it is flashing any codes
 
#3 ·
Yeah... Would really need codes before replacing anything... Especially the sensors... And if the sparkplugs have been replaced recently, they won't need replacement again for a LONG time, so see if you can check into that too...

But honestly, if the modules had issues, it shouldn't start in N either... Wondering if it was just a coincidence... Car has sat for a while, maybe things have dried off enough that it was going to start that time regardless if it was in P or N...
 
#4 ·
Thanks For your Input Datman, It has definitely sat for a long while and dried out there was no evidence that it had ever been wet inside. my understanding is that it has been a few years since the hail storm and that it has had some intermittent start issues since then. i got the car from a friends father who passed away so unfortunately i am not able to get all the details as far as what was fixed from the storm and what wasnt, as well as what sort of weird electrical gremlins have been happening. i got the car for free so it seems worth the money and effort to fix it, up to a certain degree.
 
#5 ·
If you got it for free, it's DEFINITELY worth spending some $$$ on it! I'm sure you'll agree after you take it for a spirited drive. When I first got my FX, a few people took it for a spin, expecting it to be a glorified MURANO. They didn't know it was built on the same chassis as the Z and the G, and were pleasantly surprised. Almost everyone mentioned it was the best driving SUV they've ever driven. A couple of mods into mine, and it drives even better now... :)
 
#6 ·
I had the hard-start issue for a while. I recently had the battery replaced and the car starts better than ever. Half a spin and it fires right up. Also, an intermittent issue with the door locks using the smart key has gone away.

I think these cars are real sensitive to low battery voltage and that is the source of a number of issues as the electronic components in the car increase in age. Also, a lot of connections throughout the wiring harness might develop a higher resistance due to corrosion over time, and lower voltage might trigger some issues related to that.


Just a thought...
 
#7 ·
I think these cars are real sensitive to low battery voltage and that is the source of a number of issues as the electronic components in the car increase in age. Also, a lot of connections throughout the wiring harness might develop a higher resistance due to corrosion over time, and lower voltage might trigger some issues related to that.
Thanks BigDan
I think there sensitive to grounding as well, i saw a technical service bulletin some where (now cant find it) that said to clean the grounding points and replace the bolts grounding the negative bat terminal, the ecu and 4 other grounds under the hood.
 
#8 ·
Yeah... There's a TSB with regards to killing ignition coils that refers to grounding... I'll be doing some extra grounding work this summer... There's a DIY ground kit in the HOW-TO section I'll be looking at, as well as doing what's recommended in the TSB...
 
#9 ·
since the car starts in neutral i am starting to lean away from the ecu,bcm, ac amp being the issue. i am starting to think maybe the shifter needs to be adjusted and when its in p its not fully in park, or maybe it is the park neutral safety switch. the only thing that is throwing me off about that is that it still cranks in park but wont catch. what is throwing me off is that i would think that if it was the park neutral switch or neutral safety switch it wouldn't allow the car to crank at all. has anyone had experience with either of those switches going bad?
 
#10 ·
Sorry... Never heard of this issue, but I'd agree with you that it should theoretically not crank at all... Wondering if there might be a glitch with the immobilizer that only comes up in this situation... There's an immobilizer chip in your key and if not programmed properly, it would theoretically stop your engine from turning over... But if the engine was already started, a thief could just drive away... Wondering if it was a dumb design and they only thought to have it "immobilized" when in P and never thought of someone trying to start the car in N, which if the car was already started and you were driving it, the immobilizer circuitry would not be kicking in...
 
#13 ·
Yeah... All cars have the immobilizer chip... Last part I don't know, so wondering...

Either way, it's a weird electrical gremlin that I've never heard of, so it could be the Parking Switch or something else entirely... The only time I've heard of an issue with the Parking Switch, the shifter have problems "clicking" into gear... I think the OP had spilled some soft drink or something and it didn't allow for the lever to shift properly into P anymore so he had a lot of weird issues...

Again, hard to diagnose without seeing the car... One thing you may want to do is to pull the center console... There's a DIY here with reference to switching out the finisher around the shifter... It's pretty easy to do... So pull the center console out and see if there's any water damage inside or if there are any wires that are broken / unplugged...
 
#14 ·
Well, I am glad i held off on replacing any of the computers. Datman got me in the right direction looking into the nats system (thanks Datman). Turns out one of my 3 keys had a dead transponder chip and it was the one key i was i was using. So if anyone is wonder, yes the car will crank but wont start if the nats is engaged.
I hooked up an obd reader and the only code it had was a nats key code. Deleted that and i am good to go.
Thanks everyone!
 
#15 ·
Glad it was an easy fix! Weird that it'll crank in N though...
 
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