UPDATE: a full flush and fill of the brake fluid (using dot 4 synthetic) fixed the issue. No more lights. apparently, when the fluid gets really low (according to nissan), the system needs to be completely flushed (in some cases) and filled/bled. So even just topping off your fluid MAY not solve this issue. NOTE: have have ICC, and this fix MAY only be related to models with that option, as per the ITB listed in this thread.

ok ok ok... i know this question has been asked a thousand times, but I have been unable to determine the cause of the really fun "vdc + abs + slip" lights on my 07 G35S.

I have read every single thread related to this so:

1. lights came on about 2 weeks ago
2. The fluid was at the low line, filled it up. drove it for 20 miles, no issue. drove it for 2 miles the next day, lights on again.
3. added a touch more fluid. lights went away. for awhile. came back 20-40 miles later
4. also noticed clutch reservoir was low. topped it up.
5. brakes + rotors were changed summer 2015. I also bled the brakes.
6. checked brakes: they look new and the rotors are very unlikely to be out of spec at this point.
7. checked the wires going to the wheel speed sensors. they "seem" ok. tapped on them per some comments and made sure the sensors were mounted tight.
8. reset the ecu by disconnecting the battery for an hour.
9. drove over 60 miles, no lights, then lights again after a 4 mile drive.
10. checked rear brake lights. they're all working.
11. ABS is NOT on when the car is off, as some have reported hearing when these lights come on. so no battery drain, etc...
12. the lights do not come on when starting the car...
13. I have no engine codes, at least none that I can read with my abs sensor
14. cleaned everything with brake cleaner
15. did not take the rotors off to inspect the speed sensor heads, but doubt there is damage... :/
16. I have a small squeal in the front brakes only for the first 1-2 minutes of driving after being parked over night. it's been there for over a year. noisy brakes I guess.
17. my brake pedal has begun to have what sounds like a small squeak or noise when braking. the pedal feels a bit soft as well, which probably means I need to bleed them again.

This leaves me with a few things...
* maybe a bad wheel sensor/some other sensor? How do I test them?
* trying to determine WHEN the lights come on, and it seems mostly random. I have, however, noticed that it happens very quickly IF i'm parked on even a minor incline. once flat, if I restart the car, the lights tend to go away for awhile.

So I'm leaning at this point to going to the dealer an hour away and seeing what they find.

WTF?!? any suggestions?

 

Just throwing out a WAG, but given some of the symptom variability around brake fluid levels, it seems like it could possibly be a faulty level sensor in the brake fluid reservoir.

 

i guess anything is possible. I just drove 65 miles without a light, though. ugh. this type of intermittent problem drives me crazy!

 

so it appears that when the lights come on, they only do so when the brake pedal has been pressed. I'll have to do more monitoring to see for sure but it happened at least 3-5 times today, only when the pedal was pressed. brake pedal feels a bit soft on first press, as well. second press immediately after the first is much firmer.

that says to me one of the following:
1. brake pedal switch is bad
2. brakes need bled/fluid changed.
3. brake fluid sensor is going out, and has an issue when hitting the brakes as the fluid level in the reservoir may shift at that point.



probably time for a dealer visit

 

I think you are on the right track.

1) I have seen the lights all go off due to one of the brake pedal switches being out of adjustment (the "brake pedal depressed" switch), although it was also accompanied by the ECU going into limp mode. Essentially, the ECU thought the brake pedal was being depressed simultaneously with the accelerator, which is a no-no.

2) If you have a spongy pedal, it could well be air in the line, but I would think if there was enough air to cause fluid displacement in the reservoir to the extent that the fluid level switch was triggered, then you'd have a serious loss of braking force, which you are not reporting.

3) This is sounding more and more plausible. The good news is that the part is not expensive ($25):
https://discountinfinitiparts.com/pa...&siteid=215255
http://www.trademotion.com/parts/200...Level%20sensor

 

for $25, i'll just order it and see what happens

 

Please be sure to follow up here with the results. Yours would be the first bad sensor that I have heard of, but as these cars age, there will undoubtedly be new things that start to go.

 

while I am waiting to pick up the sensor (nearest infiniti dealer is an hour away), a few additional observations:

1. the lights are seemingly random. I can't really pinpoint when they are going to come on.
2. the lights most definitely only come on when brakes are applied.
3. I wiggled the connector on the sensor. immediately after, the lights would come on the moment I would use the car/brakes. I "re-adjusted" and found that it went back to the "normal" way of lighting up Interesting...

 

Two thoughts:

1) I would not buy the part from a dealership, as they will overcharge the crap out of you. Buying it online will offer near wholesale pricing, and the part will most likely come from an actual dealership just the same. (lots of dealers have backroom online parts businesses) The part is small, so shipping will probably be a minimum, and you often don't have to pay taxes.

2) It is actually good that you are able to somewhat localize the problem to a physical area of the car and effect some sort of change in the symptoms. It could still be the sensor that is damaged (internally ?), but it could also be a wiring issue. Is there any sign of rodent activity under the hood? Sometimes those little bastards can get in and chew up critical sensor wires in places you can't readily see.

 

I found the part on ebay and at the links you provided. good to go...

I am taking the car to the Nissan dealer this afternoon. they're cutting me a break on a quick diag to see if the consultiii can detect the issue where my odb scanner can't.

given that touching the sensor made a change in behavior, I went ahead and ordered the part.

and no, no rodent evidence.

 

Ah, ok, I though you were saying that you were waiting until you could make the 1 hour drive to the dealer. It will be interesting to see what the Consult diagnostics can pick up.

 

I was, but the nissan dealer said they could scan the car today. I'm still going to do a full diag for an hour next week.

Here's what I got... they ran the check with the car on and the christmas tree all lit up. then reset the readings and only got the following:
ABS
1. C1142 PRESS SEN CIRCUIT
2. C1185 ACC CONT


I also came across this pdf, which relates to my car:

https://g35driver.com/forums/attachm...-itb07-027.pdf
from this thread:

https://g35driver.com/forums/g35-sed...-vehicles.html

Past Readings:
ICC/ADAS
1. C1A26 ECD MODE MALF
C1A04 ABS/TCS/VDC CIRC
C1A16 RADAR STAIN

BCM
B2562 LOW VOLTAGE

AUTO DRIVE
B2127 Parking Brake

4WAS(MAIN)/RAS/HICAS
C1909 CONTROL UNIT ABNORMAL6
C1920 STEERING ANGLE SEN (no signal)
C1927 CONTROL UNIT ABNORMAL 5

4WAS (FRONT)
C1686 4was MAIN ECU

so.... what does this all mean? Seems that:
a) the level switch is probably fine
b) the abs system is F'ed up.
c) most likely, the brake switch is the issue. Everything is pointing to this. The bulletin above suggests an adjustment, but it might be just worth a replacement.

 

It must just be a coincidence that when you fiddled with the fluid level sensor wiring it coincided with the brake pedal switch acting up again, which is odd, but not altogether improbable. I had wondered about the brake pedal switch (back in post#5), because I have actually seen it be the culprit myself (and never seen a fluid level sensor before).

The good news is that I doubt there is anything wrong with your ABS, since ITB07-027 sure seems to solidify the pedal switch as the likely culprit there, particularly seeing as how in the IMPORTANT NOTES it says if a [C1142] is combined with all the other codes, those other codes can be just be "in sympathy" from the [C1142] and doesn't mean there is anything wrong with any of those other systems. I'm betting that the fix is just a switch adjustment at this point. (Can you cancel the order for the level sensor?)

IDK how handy you are with DIY stuff on your car, but you can probably adjust that brake pedal switch yourself. The Factory Service Manual section for it is here: http://www.nicoclub.com/FSM/G35/Seda...5_Sedan/br.pdf
The pedal adjustment procedure (beginning page BR-7) includes the switch adjustments, while BR-19 shows the parts diagram, and BR-62 has the measurement specs for the adjustments.

 

I'll definitely give that a try. I have no problem diying it. thanks for the manual link!

 

ok. so before I dig into the parking brake switch adjustment, which is a tricky little bit... I decided that since my brake pedal was a bit squishy and I had added fluid that may have been old, that I would flush and fill the brake fluid.

Drained all 4 corners and refilled with DOT4 synthetic. While this helped a bit with the spongy feel, it had the side effect that I have been unable to get the lights to come on at all 4 2 days. I'm at 45 miles on it, and by the end of the day will be at 80 miles.

I'm still going in for the diagnostic tomorrow, but I have a strange feeling that the brake fluid may have taken on water (as it was older) and that there may have been air in the system even though I had bled it, leading to issues when braking. I'm going to try all the tricks to get the lights to come back on tonight... but... maybe fixed?

ugh.