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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.
just a quick update, I ran it down to almost empty while monitorling the mileage and the fuel gauge indication was accurate the whole time. I claim it as fixed!
Just stumbled on this thread and think I'll have to give this a shot. I have the same issue where the gas needle was halfway and then the next time I took it out, its now stuck at 3/4. Also did the on-board diagnostic to confirm that the needle works so not the instrument cluster. And when I did re-fuel all the way, the gauge went back up to full until it did the same thing once the tank was half-empty. Funny thing is that I never soldered anything but I'll probably give this a shot within the next few weeks (once I can find a good deal on a soldering iron) and update this post with new information.
EDIT 7/14: I took the AC Module eout and my part number was 27780 1NN2A. Check the resistors and no cracks. I scrolled up and found @ro0kie post about the same issue and it looks like they also tried replacing the AC AMP and it didn't work. So I'm guessing its the fuel sensor because my tank does read correctly when filled up but only 1/2 way it starts to go haywire.
I'll probably go ahead and try to clean the fuel sensors but I also bought a fuel treatrment and will probably see if the next fill up does anything different.
UPDATE #2 So when I took the AC Module out and didn't notice any cracks, I decided to plug it back in. I did wriggle the resistors with tweezers that I had laying around. Plugged eveyrthing back in and the gas read correctly. So unless it was a bad connection or the unit is acting up I'll probably evntually swap it out if needed.
UPDATE #3 I drove the car around last night and something weird happened. On startup, the gauge would start at 3/4 but then it would slowly go down to halfway (about where the gas should be). Thinking it could still be the AC AMP, I ordered a new one. For some information, the part number I originally had is 27760-1NN2A which I've confirmed it supersedes 27760-1NM6B, 27760-1NM1B, 27760-1NM6D. I found a replacement on eBay for $50.
When searching the part on eBay, I used the keyword "Infiniti G37 OEM AM FM Stereo Single CD Player Receiver" and make sure the AC AMP labels the part number with one of the above.
Replacement delivered today in and it came with the part number 27760-1NM6B. Went ahead and swapped it and immediately the gas gauge was correct. Note that you can switch the initiation to ON without the brake pedal and the gas gauge immediately went down instead of staying at the 3/4 mark. I tested it a couple times by swapping the defective one back in and it all but confirmed the issue.
Sidenote: My car which was a 2015 Infiniti Q40 has the part number 27760-1NN2A and the one I replaced it with came from a 2011 G37x. Theoretically you should be able to use any of the part #'s that are superseded.
06-01-2024, 03:35 PM
