Page DI-25 shows the wire schematic for the cluster, it's pin 7 a white/black stripe wire. You should have the EXACT same resistance to ground on that pin as you would from pin1 on the sub unit to ground. Also verify that the cluster harness pins 1, 24, and 25 have no resistance to ground (should be grounded/bonded to chassis with a green screw right behind the cluster. Page DI-9 has a picture of the harness with the pin layout.

 

Did you find a replacement for the old one that actually fit? If so, from where?

 

Howdy all. First post after lurking for months as I repair the many issues of my 06 G35X. Bought the car a few months ago w 175K miles and have replaced the radiator, the water pump, belts and pulleys, power steering pump, RF half shaft, and F brakes. None of the repairs gave me many problems, but the car recently was purring in the driveway over the weekend when it suddenly died. It had 1/2 tank of gas, and new filters, fluids, and fire (I.e. spark plugs but I wanted to use another F). So after much sensor testing and wire wiggling, I decided to positively eliminate the most obvious possibility by pouring a gallon of gas in the tank. Lo and behold, it fired right up! Guess the gas gauge doesn’t work! LOL. I filled up the tank and now it is 1 & 1/4 full. It’s like having 125% of the gas for the price of a full tank.

So, I’ve been reading a lot about the issue but haven’t had time to start testing, BUT this thread, specifically the post from jbarnett250, is the only 1 I Have read that mentions gas gauge showing way over full. With that being the case, similar to JBarnett’s issue with the gauge, would you all recommend starting with the gauge first? I mean testing the resistance at the tank is not hard, but is it a waste of an hour to pull the back seat and test?

 

Bill, just do the gauge self test and see where your needle points. My guess is it's going to point right at 3 o'clock. Everybody that I recall posting their self test results say it's slightly below more like 4 o'clock or two tick marks below half. Did your gauge ever read correctly? I don't recall anyone ever reporting a symptom of reading high due to problems in the circuit that require repair. The gauge reading half tank when empty is fairly common. You need to fix that problem first. And debugging that usually starts with measuring the senders. If those are good, I'd go to the combo meter next.

 

It takes 5 seconds to pop the back seats, there's two little tabs that you pull forward and the seat bottom lifts from the front and slides right out. No tools needed.

Definitely check the resistance values at the harness, that will tell you positively that the problem is with the sending units or that the problem is NOT with the sending units. You can remove the back seat, unplug the harnesses, take readings, and be done in under 5 minutes the first time, once you've done it a few times it's a 2 minute job.

It's about a 50/50 split whether it's the sending units or the dash that failed.

If you have an overfull reading you don't even need to wait for a full or empty tank, just take the resistance reading and see if it's within spec, you can probably guess how much fuel you think is in the tank just by going off the odometer since your last fill-up.

 

Thanks for the reply J. I’ve only owned the car a couple of months and it came with a “full” tank. I’ve driven the car a bunch but never put gas in it because it had “half” a tank. Joke on me. Just an odd issue to have on any car. The only vehicle I’ve ever owned with a gauge that never reads right is my 78 Super Beetle. The problem there is that the new aftermarket parts have a different impedance than the OEM stuff, so getting them to talk to each other requires a change to the voltage. But I digress.

i found the gauge self test on this forum (turn key on while holding the trip reset, wait for all 0000’s then hit the reset 3 times within 7 seconds). I must not be doing it right, because my gauge(s) never do anything. It’s supposed to make the water temp and the fuel gauge go to half, right?

thanks for the resistance values, cleric. I will start the diagnostics tomorrow and see what the senders show. Right now the tank is completely full, so I should see a resistance of ~3 ohms. If it checks out OK and the gauge is the culprit, I just might add an aftermarket gauge w 0-90 range to keep an eye on things. Should be able to run it directly off of the primary sender (on the pump).This car is a family car (me, wife, and oldest daughter all drive it). Hate to have somebody out and about run out of gas.

 

it sounds like you're doing it right to get into self test mode. but once in self test mode you have to push the button to get the needles to go to the test positions. this thread has my description of how i did it.

https://g35driver.com/forums/g35-sed...ter-reset.html

 

Well gentlemen, worked on the G35 this weekend to determine if it was a gauge problem or a sending unit problem. Definitely gauge. I pulled both senders out and check resistance at top and bottom. Both were very close to spec. Main sending unit read 6.xx ohms full and 78.xx empty. I consider it with the tolerances of my old Craftsman meter. Reinstalled and plugged it all back in, but no change. Without getting into the hassle of repairing the cluster, my options are limited.

1) install aftermarket gauge somewhere or

2)use the trip counter and fill up every 250 miles. The car has the nav and info system that pops up from the center of the dash. There is a function that estimates fuel economy and distance to empty. It estimates current DTE of 250 (car is not quite full. I took out 2 gallons before I tested the sending units).

think I’m goin for option 2 unless I get a wild hare and want to dig into the cluster (not)

speaking of fuel economy. I was surprised to find the car only getting 20 MPG. It’s a big motor, but I thought it should be better. I have changed all fluids and filters. Tires are high full (10% high BC I live at 7000+ ft) but I had yet to change the plugs.

old plugs were NGK R and the gap on them was obscene! Old plugs ranged from 0.65-0.73. Factory plug gap is 0.44 so I’m impressed how well the car ran with old plugs. Wonder if they were original?

new NGK iridium plugs installed and the car sounds and run beautifully!

well, almost. After I replaced the plugs and got everything put back together, the engine.started to make a weird buzzing noise on the top end of the passengers side. It almost sounds like a fuel injector going bad. So I grabbed my long screwdriver and listened to the bearings, the igniters, the CPS, and anything else that didn’t move. Still couldn’t find the noise. Only by dumb luck did I find the sound.

drum roll please; the new PCV valve! Replaced the old one w off the shelf from O’Rielly. It makes that weird buzz/rattle. Pinched off the breather hose and the noise stopped. Ordered OEM from Nissan so it should eliminate that noise.

I’m getting a crash course in Infinity. Have to admit, they have a lot of “personality “

 

I would just source a used instrument cluster off eBay. There are also folks on eBay who rebuilt the OEM cluster but I've heard both good and bad experiences from people getting that done.

 

I'm not 100%, but I recall reading somewhere on this forum of a place that rebuilds the instrument cluster, somewhere east coast. IIRC, there are some resistors that burn out causing the gauge to read wonky. I had an 05 sedan, and the gauge always read F to 3/4 tank, so I just drove off of the trip meter since it was a high mileage car, aka not worth fixing. My current 04 sedan gauge has worked flawlessly (knock on wood) but I still reset the trip every time I fill her up!! I guess its a good habit lol.
I do mostly short trips home and to work, and I average 17.5 to 18, same for both this and my last G. When I have taken longer trips (to take my dad to the hospital mainly) I get 22-24 depending on traffic.
Oddly enough, I replaced my PCV valve with a brand new one from Nissan weeks ago. It made the same damn noise for 10 minutes when my buddy and I first replaced it and fired up the car. My buddy and I were looking/listening all over the engine bay trying to find that damn noise, drove it around the block and it stopped. Been a few months and it never has buzzed since. Maybe the internal valve rattles when there is no oil vapor sticking on it.

As goofy and quirky the problems are that these cars have, I'd still take these over anything german. With good tires, these cars can handle very well. My 05 had 250k+ and it pulled a 328i in the canyons. 335i's well.... not a chance

 

New PCV from the dealer is good. No more buzzing. Maybe 90% of aftermarket are fine, but I’m so **** retentive that it was worth the $ to get rid of that noise.

And don’t even start on handling/suspension. I’ve been so busy fixing all the other problems due to neglect that I haven’t even touched the front suspension. I have a definite clunk in the front driver’s side when I hit a bump. And I’m not confident about my FL wheel bearing. Seems like there is a bit of noise coming from the bearing since I replaced the half shaft. May be paranoia since I just went through this w my wife’s Toyota. Spent a weekend pulling the half shaft and reinstalling. Turned into a nightmare of a job since the axle carrier bearing was rusted into the pedestal. That job involved a lot of creativity. But I had to go back the very next weekend and tear out the front wheel knuckle because the wheel bearing started grinding after I put in the new shaft.

ive seen “complete front suspension kits” on line that consist of upper/lower control arms, ball joints, etc. Anyone gone that route before? Not interested in “performance” upgrade or lowering the Sedan (the car is used by all 3 drivers in the family) just wanna stop the clunk and make sure it doesn’t destroy tires.

 

The complete kits are fine for daily driver duty. I wouldn't expect to get another 100k out of them, realistically more like 60k before low grade components wear out on the front of a G but that's still a pretty good amount of time before things START to wear out.

I do recommend you try to find a budget set of adjustable upper control arms. There is no camber adjustment on the OEM ones and having the ability to adjust it means better spec and more tire life. The downside (maintenance perspective) is that they will typically have poly bushings and will require a little grease every other oil change or they start to squeak.

 

I'd start with checking the sway bar end links. Both my G's needed them when I initially purchased them. If they're bad, don't get cheap AC Delcos, I got them and they were very poorly made. OEMs are about $45 each, aftermarket are around $30 on ConceptZ's website as I remember. Next guess would be compression rods.
I've heard plenty of good and bad about aftermarket suspension parts. My opinion is any part with a ball joint you should try to go OEM, I've had garbage luck with aftermarket ball joints failing in 10k miles on other vehicles. I like the idea of adjustable upper control arms! Z1 makes some nice units I may pick up sometime

 

I have the Z1 FUCA, they're good, and when the ball joint wears out you can buy another one to replace it.