Intermittent ABS Problem on 2006 G35

Hi everyone,

Having an intermittent issue with my G35 and I think I know what the problem is. I'm just looking for some guidance this problem appeared after I fixed the following:

1. Both rear wheel bearings
2. Replaced rear diff axle seal
3. Replaced RAS motor
4. Replaced my parking brake hardware
5. Cleaned up the ABS sensor and tone ring on my rear diff output flange (It was covered in dirt, grime, and gear oil). I was pretty delicate using electrical cleaner, but I think I might have ruined the sensor itself.

Basically, what happens is this:

When I am driving at low speeds < 35 MPH and I press the brakes my ABS kicks on making it hard to stop. The ABS, VDC, and SLIP light all turn on and then my RAS turns off until I turn the car off. When I restart the car the cycle repeats itself more frequently now. After the lights get tripped the sensor I cleaned will display 0 MPH on my Autel. When it's working fine I see the speed at which the car is moving. The code I pull from the ABS module is C1105. I believe the computer sees 0 MPH from the wheel sensor, so it engages the ABS thinking the wheel is stuck.

I have access to the FSM for my car and I believe my ABS sensor is an magneto hall effect sensor and it only has two wires going to it. If I understand this correctly one is the 12V supply and the other is the signal wire. I have an entry level Picoscope (non auto), but if I probe the signal wire I should see a square wave correct? I plan on doing another visual inspection before I condemn my sensor, but I was hoping for any other suggestions.

The FSM also has this caution:

Do not measure the resistance value and also voltage between sensor terminal with tester etc., because sensor is an active sensor.

Does that just mean you can''t use voltage and normal resistance checks, because it's a digital sensor?

On these active hall effect sensors the signal is actually a change in the current flowing through the sensor. The ABS module supplies near 12v power to the sensor on one wire and it returns to the ABS module on the other wire. The ABS module monitors the current on the return wire.
Doing resistance checks or looking for a voltage from a disconnected sensor although unlikely to damage the sensor just won't give you any useful result. Also the ABS module shuts down the power supply to the sensor if it detects an electrical issue after power on self-test.

The hall effect digital on/off/on square wave BUT because there only two wires the sensor is powered and grounded through the same wires the signal current is superimposed on the 7ma or so current used to power sensor.



With an osciloscope set to measure AC voltage you should be able to see a similar pattern back probing the sensor.

This type of sensor is really sensitive to the clearance air-gap between the toothed wheel and the sensor as it will cause dropouts in the signal.

Andy has the right idea as far as testing these sensors. To be clear, what year is your G35? Two or four door?

You can totally do resistance measurements, but you get stuff like this:



The manual says not to them because some techs will see that number and (incorrectly) call a bad sensor.

Because most G35's I've seen integrate both rear sensors into one harness (as you saw), scope testing will be a bit easier. If it's truly a RR WSS problem, you'll have the LR sensor signal at the same connector to compare to. :lol:

For reference, I dug up some known good waveforms from other Nissan digital sensors. The exact voltage values will vary depending on if the engine is running or not, but you're looking for around 800mV difference from high to low on the sensor output.

Thanks for the detailed answers guys. My G35 is an 06 coupe. When I have some free time I'll check out the sensor visually and figure out how use my scope, since I'm a DIYer and only bought one (albeit cheap one) after watching a ton of scannerdanner videos.

Let us know what you find. Post up the captures, if it's not too much trouble. I'd be interested to see, as this sensor clearly works at least some of the time. :silly: