gas gauge level not working
 

Quick Update: some of you know that I was having a lot of problem when the gas gauge was not reading the gas level properly for the longest time the level was stuck at 3/4 no matter what, I brought the car to 2 infiniti they said paid $150 for diagnostic
the first one said to change the sending unit and fuel pump,
the second shop said they do not know the problem and are waiting for infiniti to send some for the fix and a lot of infiniti are having the same problem
I brought it to another local shop on Thursday and they did test the wiring and continuity, they even change the sending unit and fuel pump that I had bought on ebay and at the scrap but nothing. the mechanic had a software that he pays 200 a month and looked again and saw something called A/C amp. He said if we can get this part we can try if it work it work if not we will do more test. Unbelievably I took one from the 2010 g37x at Kenny u pull from Montreal couple of months ago, brought it to the shop at 5 AM and I took apart the center of the dash and connected the A/C amp and we started to do some test.

1- We took 2 other sending unit and fuel pump
2- both level from the sending unit and fuel pump were on empty
3- We turn the key to ON and the gas gauge on the cluster showed empty
4- We turned the car off
5- We took both level from the sending unit and fuel pump we raise to half a tank
6- We turned the key back to ON and the gas gauge showed half a tank and the mechanic was happy he said there you go it worked.
7-He said that sometime even experience mechanic would of never find that problem
8- He said to keep him up to date when the gas gauge goes under half So If you change the sending unit and fuel pump and still are having the same issue where the gas level will not read past 3/4 of a tank no matter what you do, the way to fix it is to change the Climate Body Control Amplifier Controller Module BCM https://cimg8.ibsrv.net/gimg/www.myg...ff94c23a1b.jpg
its behind the radio removal and installation took 15 min top and everything would go back to normal.
hope you guys could pass it on to the other driver.


I praise that those mechanics, Infiniti should of known how to fix this issues especially when I paid $150 to have the car diagnose. not cool from them.

Gas gauge issue
 

Hello I've been having a fuel gauge issue where my fuel gauge needle is always passed full. My mechanic changed the fuel pump with sensor and it didnt work so we returned it. Would the amp unit controller fix my gas gauge issue or would it be the cluster? Please someone help, I've had this problem for almost 2 years and I never know how much fuel I have and I get stranded on road half the time. Thank you guys

I know I'm really late replying, and only because I'm having the same issue, but you can run diagnostics on your cluster to see if its the problem. if not, it is most likely the AC Amp.

With the car turned off, hold the trip/a/b button. While its pressed, press the ignition button twice with foot off the brake. release and press the trip button 3 times. This should put you in diagnostic mode. Holding down the trip button will move the coolant and fuel gauge to half, and letting go will move them back to 0. If they do this behaviour and look symmetrical left and right, your cluster is fine. If the fuel gauge doesn't move, doesn't go to 0 or doesn't reflect what the coolant gauge is doing, its a faulty cluster.

I have the same problem. I replaced both sending units but the fuel gauge stays full. You said the Body Control Module is behind the radio but when I goggle how to change the BCM it shows it by the passengers feet and does not look like the part you are showing. Can you help me out?

It's not the BCM, it's the AC Amplifier module. Make sure you look at yours first and find the exact number because they're manufacture year and month specific.

So just remove the radio and its right there? any other things I should know?

Nope, that's it

Thanks for the help guys!!! It was the ac control module. Fuel gauge finally works

Awesome, congrats. Glad we figured this one out. Took me a year to figure it out haha.

I should mention for the next peeps doing this you will need a torx screw driver to remove the module and I had to reset the air bags after cause it started blinking after, what was easy to do after a google search. I have a 2013 and I ordered one on ebay from a 2012 different part number but it worked,

Right, I forgot to metion that part.

Thanks to all just ordered AC module, gotta pass inspection next month. Fingers crossed!!

So, if the gauges both move up and down in sync then the problem ISN'T the Climate Body Control Amplifier Controller module - correct? Wondering because I have a 2015 Q40 that is having this problem and I am wondering if it is the sending unit or something else. Thanks in advance for any feedback and of course for the info that you've already posted - hugely helpful!

I think it only affects the fuel level signal, not any other gauges.

I'm having the same problem with my fuel gauge. 2008 G37 base.

I replaced the whole fuel pump assembly, sending unit, and AC amplifier.

AC amplifier I replaced with 2 different units. Both numbers matching. Same issue,

Is there any sort of reset that needs to be done to get it to work correctly?

Nope, it just worked after new AC amp in my case and same for a few others that have tried this fix.

Thanks for the quick response. I was really hoping there was an additional step I could take.

No chance anyone knows how to fix one of these? I don't want to keep throwing money at used parts that are broken.

I'm honestly stumped. The AC amp is usually the last resort when all else failed. Maybe a wiring issue? Like fuel sending unit signal being cut somewhere. Grasping at straws. Gauges worked when you did diagnostics, right? So not the cluster? Really stumped on this one.

Checked the cluster, it works as it should.

I'm assuming the replacement AC amps were bad because the airbag light started flashing after those were installed. The airbag light does not come on with the original AC amp.

Hmm, now that you mention it, if I remember right the airbag light was flashing for me too because the panel with all the buttons was disconnected. Had to do the reset for the airbag light. You just cycle ignition a few times. Just YouTube resetting SRS airbags light on g37. But that wasn't really related with the AC amp as much as it was because things got disconnected. I can't say for sure in your case though.

Do you know where I can find instructions for swapping this out? I'm willing to pay for an online manual.

Thanks,
Bill

Factory Manuals- Free
Navigate to your specific year and type and download section:
MWI (Meter, Warning Lamp & Indicator). I would recommend you download the whole manual while you can.

There is also a video that shows how to remove the gauge cluster.

⚠️Keep in mind that your mileage will change if you swap in a different cluster. This may or may not be a issue for you.

I changed out everything and mine ended up being the AC amp. Just look up videos on removing the navigation and the Ac Amp is behind all that. It is not cheap so if you can find it at a pull a part. Just to refresh you remove the shift knob and then you can get to the screws to remove the navigation and stereo.

Might be in the dit section, but I'm not sure. I just went in there and figured it out by sight.

I’m sorry I’m late to the party and I hope I don’t anger anyone who replaced the HVAC Control Module. You can solder a resistor and fix it for the cost of a solder. See pics for reference. Literally registered here to save some fellow G37 owners a few hundred dollars if you have soldering experience!!! I realize after posting, the picture is poor quality. I pulled the Control Module apart and found the resistor had a crack on the original solder. If it is shifted or cracked, that is your culprit. It can be any of the resistors in that set. I did not buy a new resistor or whatever it really is exactly (believe it is a resistor). They just tend to break for some reason, resistor will still be reusable. Just cover up the crack, and you will be good to go. The circled resistor in red is my bad one, you can see the line going through the solder and that was my case.

https://cimg8.ibsrv.net/gimg/www.myg...0b85d416e.jpeg

Did you have any luck correcting this problem? I also have 2015 Q40 and just wasted $900 with my mechanic on replacing the sending units. Did you try the AC Amplifier Module?

yes i did replace the ac amplifier and i did the same and bought all the random parts but the culprit was the ac amplifier behind the head unit. Go to a pull a part if you can.

Thank you!
 

I just wanted to create an account and give a big thank you to all of you who have identified this issue. I know this is very late, however, I was able to re-solder the resistors and my fuel gauge is working again after replacing the fuel pump, etc. thank you guys so much!

Glad that worked. Mine was the white box behind the navigation lol

Good to know. I paid a lot of money to have my mechanic replace the module. Will look at re-solder if the problem reoccurs.

A/C Amp Meter / Fuel Gauge Not Accurate
 

- Hey, I own a 2011 G37x Premium and I took my car to the dealership for a diagnostic and “A/C Amp Meter” came up. Because my fuel level haven’t been accurate even after I change my fuel pump system. I found an A/C Amp Meter online for $180. My two questions are, is it “Plug in and Play” ? Once you swap that did it start to work ? I love this website hopefully someone get back to me ASAP.

Well it is plug and play as long as its the right version of the AC Amp. it has to match to the one in your car, so hopefully you bought the correct one. I found one on ebay for $25 and that fixed my issue.

I would not pay $180 for a used unit. There are plenty on eBay for a lot less- you just have to search thoroughly for them. A trick I have found is to search for used AV headunits ("G37 25915") as many sellers do not separate the amp from the headunit and sell the whole unit. Plenty can be found for $50-75 and, upon receipt, just swap the amps and toss the headunit.

As hexotic mentioned above, completely plug-and-play but you must stick with your car type (ie. Coupe, sedan, 'Vert). It is not suggested to "mix-and-match."

hey guys just made an account to reply to this!! I’ve been having the same problem man! I had my fuel pump replaced and the sending unit replaced too. But as most of you guys here the fuel gauge still isn’t back to normal. I will try doing the diagnostics on my cluster to see if that’s the problem! Thank you guys so much for this information and I’ll keep you guys updated too!!

So i tried to run diagnostics on the cluster but I can’t seem to do it right. I followed the steps exactly how they were explained above and I can’t seem to get it in that mode. Now I have a 2010 G37x Coupe and not sure if that makes a difference. Any help would be appreciated!!


Edit: now I replied to this thread last night but some reason it’s not showing. But I got a p0462 code and my gas level wouldn’t go down at all as it stayed at full all the time. So i was told to replace the fuel pump did that and still stuck with the problem. Replaced the fuel sending unit too and still my problem wasn’t fixed. So by reading through this it could be my ac amplifier so I’ll probably order one soon and get it swapped. Hopefully it’s not my cluster but as stated above I can’t seem to self test it myself so any help would be appreciated thank you!!

99.9% of the time when the fuel gauge acts up it is the amp, not the cluster. The only common issue these clusters have is the LED backlighting which is unrelated to your issue.

That said, with your car running, are you able to cycle between the TRIP A and TRIP B odometer readings? If you can cycle through the A/B, then the switch is good. If not, then there's a different issue.

Here is the method. Timing is key! https://cimg2.ibsrv.net/gimg/www.myg...a94df52f8d.jpg
https://cimg0.ibsrv.net/gimg/www.myg...8a5163ee95.jpg
Key must be ON, not in ACC.

I can cycle through Trip A and trip B just fine while the car is running. So I guess then it’s the Ac amp? If so I read that you mentioned to buy a “AV headunit” and Just take out the Ac amp and install it. Might do that since the ac amp itself is quite expensive too. I’ll keep you updated!

Did you try running the diagnostic again? Never hurts to try and verify the needles move.

On eBay, many sellers lump the AC amp with the AV headunit and more often than not the price is significantly lower than buying just the amp. Take your time searching and try to buy from reputable sellers.

Just note: you have a Coupe. The donor part must be from a Coupe. It is not suggested to "mix-and-match" from the sedan or 'Vert.

Okay I just went into diagnostic mode and everything is working well. I made sure the gas and the coolant went to halfway in sync and they did. Everything else moved in sync too so I’m guessing it is the ac amp then? Thank you so much for the instructions too it helped a lot!

Hey guys so I found the part number which I need and it’s 27760-Jk71B, now I can’t find any of that exact number but I did find some but it’s 27760-Jk71A. The only difference is the last letter . Now would that make a difference just wanted to ask this before purchasing.

As long as it is from a Coupe (same as your car) you should be fine.

Alright thank you! Now I also did find one with the same year as mine and a coupe. But it was from a g37 not a g37x which is the model I own. Would that be a problem as well? Sorry for so many questions I just bought the car and I wanna make sure I do everything correct!!

You're good to go as long as it is from a Coupe. That is the only differentiator in this case.

Alright thank you so much! Will update when it comes in and when installed !

It goes without saying, but I must point out two things that are VERY IMPORTANT to this repair:

1) Be sure to disconnect your battery BEFORE starting this job.

More importantly:
2) The amp has 2 connectors. Take a sharpie marker and MARK which connector goes where BEFORE unplugging them from the amp.

It is VERY easy to mix up connectors for the amp with some from the headunit. Take 2 minutes and mark the 2 connectors for the amp so as not to mix them up when you put everything back togrther. This step will save you from potentially bricking the car.

Alright will do. Thank you so much yet again, hopefully this will resolve everything!!

Hey, I also have the P0462 code, I just re-soldered the resistors and reinstalled the amp but my code didn't go out, also at a full tank so I'm gonna run down the gas to see if it fixed my gauge at least, I took my scanner and manually erased the code so ill see if it comes back on, please let me know if replacing the amp clears the code for you so ill know if my amp is faulty or I'm just a bad solderer.
​​​​​​​

Yes fixed it
 

Yes! Resoldering the resistors managed to fix the fuel gauge and my service light hasn’t come back on
https://cimg8.ibsrv.net/gimg/www.myg...7930b3ba0.jpeg
The 4 resistors in the middle of the board I only resoldered the 2 but just incase im gonna resolder the other 2, might need a magnifying glass and good light to see the cracks

Fuel gauge or something else??
 

So I’m having an issue and trying to figure out what it could be before start throwing $$ away.
Long story short, I was having the issue of the amber key light and most of the time couldn’t start or turn off the engine, so like every one else, went to my mechanic, supposedly the issue was the BCM, no fix, then steering lock module, no fix, took it to the dealership, replaced ipdm, half fixed and now I figured out that I had water leaking in and going for the wires and making the car go crazy, so my guess those modules never were the issue.
My concern here is that although my fuel gauge seems to read correctly, the huge fluctuations I have in range it’s just nonsense, after filling up, sometimes shows 373km range and by the end I only make around 280km, last time I filled up I only had 243km range, already did 79km and it shows now 254km range, according to the info in the cluster/screen shows 24L/100km…..but the needle gauge works properly, I think.
I’ve noticed the first 100km the needle drops 1/4 tank so technically it should last around 400km, but nope, once it hit half tank, I get little over 100km with the remaining half tank.
Every morning I turn on the G and let it warm up, everything seems normal, as soon I start driving, just like that 10-15km range just “disappears”.
I have this G for 6 years now and the highest I’ve seen was 15L/100km during the winter since it takes longer to warm up at negative temp.
Already replaced the control unit btw and same outcome, so at this point I’m thinking the sensors.

I tried this but it didn’t work so you have an idea of what it can be

G37x Fuel Guage Issues
 

Not sure if this thead is still alive. Similar issues to other posts about. Normal cluster self check, replaced fuel pump, Driver Side float sensor, AC Amplifier. Fuel guage works not but is very erratic, sometimes 50 mile swings in range with moving fuel level needle. Is this normal? Seems to go to full when topped off. Also had issue with leaking sunroof on BCM. Does Fuel level power come through BCM? Trying to get this behaving correctly and wondering if a BCM fault (no codes) might be causing voltage variations within normal range causing displayed fuel levels.

Thanks,

Tim
2013 G37x

Ac amp
 

It is the ac amplifier or was for me. I did all you mentioned and it was the stupid box

Hello Everyone , I just wanted thank OP @flipmode007 Thank you. Your posting helped me resolve my gas gauge issue and eventually save me some $$$.
I just wanted to point out that i had to take very close look at this before applying solder thanks to harbourfreight i was able to do buy and solder this all in afew hours
Note that you do have to look very closely, using my phone camera and zooming helped me.

https://cimg2.ibsrv.net/gimg/www.myg...16aa0c58eb.jpg


Thanks
J

Coming in with another question re: part #'s, quick background:

I have a 2012 G37x, ~120k kms, same issues as many posters; fuel gauge started getting slightly wonky, then very wonky, and now throwing SES light. I'd be fine with just going with trip reset for fuel but the SES light is beyond my ADD tolerance. Looking to replace AC amp as first step before pulling apart fuel system components. I pulled the center console today and found my AC amp part number "27760-1NM7D", and, alas, there are no used parts available with the exact match. Closest I can find is "1NM6D". Having read through many posts, I understand best practice is to replace with an exact match, otherwise various problems can spring up, however:

Would anyone know what the difference is between "7D" and "6D"? If the potential issue/feature loss is something extremely minor I could live with it. If it's playing with fire to go with non-exact match, though, I'll pull it and find someone to solder the resistors.

Any advice appreciated.

Great question, I wont be able to tell you whats the difference but I know that most parts are interchangeable. . All I know, I went to the scrap yard and grab one from a 2010 and mine is an 09.
Anyone can correct me if I am wrong.

Follow-up: I finally managed run the tank low enough without the wife filling it prematurely out of fear (ran out of gas when it started acting up a few months ago) and managed to dump fuel system cleaner into the tank before a fill. Cleared the CEL and went round trip Toronto to Montreal (1,000km) and some other around town driving the last two weeks, 3 fills since the cleaner and things seem to be back to normal.

Hoping it was only some gumming up of the sender units in the tank and system cleaner at every oil change will keep the issue at bay. Will update as things go along.

I guess i spoke too soon, my gas gauge now stuck at 3/4 mark . I have driven 204 miles since fillup and that should put the gague right between 1/2 and 1/4 mark Any suggestion on what i should do to fix this

Thanks
https://cimg2.ibsrv.net/gimg/www.myg...437e97cd89.jpg

A huge thanks to @BlackG37CT for pointing out the cracked solder joint on the resistor on the AC Amp board!

My story;
Tank ran dry the other day in traffic even though the car was showing a 1/4 tank...
So I had to do the whole coast to a stop, make that phone call ... 'sure it said 1/4 tank Beefy, i trust you...' then filling with a gas can for the enjoyment of every passer-by, etc. : (

-BTW, I almost never run it this low, so who knows how long this issue was baking - although I have been ignoring the P0642 code for about a month. so I am partly to blame.

Anyway, after getting home and vowing to never go below a 1/4 tank again, I ran my issue through the forum search to see what was out there for help and guidance.
And after a first run and skimmimg through the topics, I resigned myself to opening the tank to clean the sending units and locating and saving an AC Amp on eBay for possible future ordering. And priced some sending units at Napa.
But before completely giving in to spending $$, I read a bit deeper into the threads and discovered @BlackG37CT 's post about the cracked resistor joint. A reprieve was offered! And accepted!

So with all the enthusiasm that I could muster at my age, I tore into the dash, expunging it of many vital components, various screws and other unmentionables that happened to be inside there. This activity occuring a mere few hours ago.
And all that effort paid off in a big way. Because as soon as I extracated the Amp and disemboweled it, I found one of the four resistors on the board had a cracked solder joint. Holy poor manufacturing processes, Batman.
I did my best micro-min solder job (will not share that picture...) and put it all back together nearly the way I found it.

Then powered up everything, made sure none of the smoke escaped from the wires and boxes, put away the extra screws for some project down the road and ran it through a nice op check.
Not only did everything work, but the CEL was cleared as well!
I claim victory and accept my points for this round.

Now I will have to do some real world testing and watch my mileage as the needle goes down and hopefully it will dip below 1/4 tank and provide a trust worthy indication.

Time will tell and I plan to update this post with the results.

here is a pic of the bad solder joint.

https://cimg5.ibsrv.net/gimg/www.myg...2a50b3e5ba.jpg