My G was having repeated faulty ABS actuation. It would actuate a few times when I first started to drive, then the ABS/slip/VDC lights would come on, and the car would drive fine. My assumption was the computer was disengaging those systems. I checked the ABS code, and it was C1108. I had the car in to replace upper control arms (and ended up with new CV axles as well ) and I asked the mechanic to check the ABS sensors. He said it was bad. I had already ordered a new one and have replaced several sensors with no issues. After putting in the new sensor, the car will not go over 10 mph. I tried putting the old sensor back in, but still, I cannot get the car out of limp mode. Any thoughts? I'm worried that the ABS system may need to be reset somehow, or may be damaged.
Thanks for your help.

 

C1108, front left wheel sensor.

You can disable the ABS system by unplugging the relay box, it's mounted right next to the brake booster, on the back of the fender well. There are three harnesses on it, disconnect your battery, then disconnect those 3 harnesses, then hook the battery back up.

This will keep the ABS/VDC/TCS system from putting your car in limp mode. Your ABS/VDC/SLIP lights will be on though, it's a band aid until you get the wheel sensor fixed.

You will not have antilock brakes, or traction control, until you get the issue fixed and hook the relay box back up so don't get squirrely going around corners.

 

Thanks!!! I eventually pulled the VDC fuse, and that seemed to work as well. But I like your solution better. When I was double checking my installation of the right ABS sensor, I noticed that the CV axle doesn't seem to have a tone ring with teeth. There is just smooth metal under the sensor.

passenger cv axle
Is this my problem? I've heard of some CV axles having smooth ABS rings now, but I feel like this couldn't work the same as 46 raised teeth. Did my mechanic give me the wrong axle?

 

I would certainly think that would cause your problem that you are having. If it can’t read the speed of the wheel it will freak out. You mentioned you replaced the sensor, but the sensor in the pic looks original or like it’s been there for quite a while.

 

Yes, good eye! This pic is with the original sensor. I didn't want to confuse the issue with the entire story, but here goes. I was getting an 1108 (driver front ABS) code when I took the car in to have new tires mounted and balanced. Upper control arms had to be replaced because ball joints were shot. I asked the mechanic to just test the left front sensor while he had everything off. While changing the passenger side control arm, I guess they tore the boots on the cv axle, so they replaced that axle as well (but probably had to scramble for the part since they weren't planning on replacing it). Then they tested the sensors, and told me both left and right were bad. I was skeptical because I only saw a code for left when I brought it in, but when they returned it, it showed both sides. I figured it might have been damaged while testing, or whatever. No biggie. Here's the key, the car drove home fine because the computer had already disabled the ABS/traction control (3 lights) when I took it in (due to the left front sensor's inconsistency). I had already ordered a left front sensor (but not the right!), but saw another 05 g35x had just arrived at the pull your parts junkyard. So I grabbed one there just to test. I put that in along with the new one on the drivers side and then made what might have been an error. I cleared the ABS code with a scanner. Limp mode... etc ensued. Honestly, my right sensor wire looked in way better shape than the junkyard one, so I put mine back on when I realized the problem might be lack of a reluctor ring on the axle. Sorry, now this is way too long.

Main question, does anyone know of a reluctor ring out there that could work with my sensor that looks like that? My understanding is that these are simple magnetic devices that create an on/off current as each tooth goes by the sensor. It seems unlikely (but possible?) that the smooth ring shone above has 46 magnetic poles inside that would match a toothed ring's signal. My mechanic wants to charge 5 something to replace both sensors to fix the problem. I don't want to drop 200 (his price) on a new sensor if the axle is the problem.

 

I'm almost 100% sure that's the wrong axle. They always have a pickup ring on them nowadays.

Go down to an auto parts house like Autozone, Napa, etc and have them pull a front axle so you can see if it's got a ring on it.

If it does then take it back to your mechanic and tell them they used the wrong part.

 

It's not magnetic either, the sensor is a little coil of wire sealed inside plastic. When the metal teeth of the ring go past the coil it generates a slight magnetic field that quickly rises and falls. This is creating a FREQUENCY that is read by the computer.

Wheel speed sensors
Cam sensors
Crank sensors

They all work the same, they're called "hall effect sensors", you cannot read them with an OBD2 scanner or a digital multimeter. You use an oscilloscope.

Camshafts and crankshafts have a unique configuration of teeth on their pickup ring. This way the ECM knows which one is which

Wheel speed pickup rings are typically just evenly spaced teeth.

 

Limp mode was definitely caused by the lack of tone ring on the axle. Mechanic agreed and replaced the axle. But my new left front abs sensor still appears to not work. I sure hope there isn't a fault in the wire between the abs relay and the sensor harness clip. That's one complicated (and hard to reach) set of wires in the harness running between the two. I guess I need to get an oscilloscope. I have a junkyard pulled left sensor and relay. I could try those first...

 

Now im a bit iffy on changing my abs sensors up front, had these 3 lights on for awhile but never had a limp mode issue and im positive its those sensors after messing with the wheels when trying to change the ball joints. Im definitely gonna take a look at the CV axle

 

Did you check section BRC of the FSM? There's a few steps that use a simple meter to check the wheel sensors, wheel sensor power supply, etc., before you go dragging a scope into this.

 

So MikeG35Coupe's advice led me to check continuity next. It then finally occurred to me (DUH!!! ) to check and see if the right and left sensors were the same part. Yep! same number on the wire. That could clarify any continuity question right there. So I just swapped sensors, cleared abs codes, and sure enough it was 1103, right side abs sensor. Nothing about the left (so far, anyway). I have some ideas on why the new and junkyard pulled sensors don't work (slightly different harness clip, don't seem to mount as snug). I ordered another one from parts geek that seems to look exactly like my original (although not the same part number, that no longer exists from what I can find online). Fingers crossed. I'll let you know. If you are wondering about an after market ABS sensor, I can tell you this. If the original wire clip is grey, the blue one has a slightly different shape (wide side slot and narrow side slot are reversed in position). The oval shape of the cross section of the sensor may also be oriented 90 degrees differently. If my new grey clipped sensor works , my study of one says don't buy the blue clipped sensor even though amazon, rock auto, parts geek, and everyone else seems to say it works on your g35 sedan.