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Seems the A7/3 is called different things, but it looks like an ABS controller. I'll see if XENTRY has test procedures for it.
ahhhhh that makes sense. That was my #2 suspect behind the yaw sensor. I found a company that will go through your existing one and repair/rebuild for something like $450 and it mentioned that since it was your original unit it didn’t require separate reprogramming. Maybe the smart path would be to see if they charge the full amount if they determine nothing is wrong. On a generic iOS code reader I got an inactive c3266 code and that code was mentioned on their page. Although the code definition was something generic like companion fault or something to that effect. It did not show up on my icarsoft scan interestingly enough
I thought about that. When the problem first presented it was on old pads that were about spent. I put new ones on and it still happened. Not that that would rule out the caliper piston, just my line of thinking was that piston is in a completely different spot now that when it started. Still a possibility, but I had seen either OP or possibly another person with same problem who had tried new calipers to no avail.
if it was calipers though, would it have instantly released when I opened the bleed screw? (I’m asking- that’s not rhetorical)
If there is some dirt trapped between the caliper piston and bore, or the dust boot is not correctly seated, then the piston may not always retract when the bleed screw is opened. But, reading through the latest posts it looks like your piston is being commanded to close rather than the problem being mechanical in nature. I think you're on the right path with the ABS control unit.
Any idea what it means if anything that those two codes are listed as “archived/inactive”? I assume that means they were recorded faults that aren’t actively faulting at the time (which would go along with the intermittent nature of this problem).
btw I appreciate everyone’s insight and input on this. I just needed a sanity check before I started slinging (moderately expensive) parts.
i recently had an equally bizarre problem on my daughters jeep where it felt like the AWD driveline was binding. After loading it up and towing it 4 hours home it turned out to be a wheel sensor that ohmed out just fine but when viewing it in live data would drop out and make the ABS grab a random wheel and brake hard. I’m not entirely sure what I did to **** off the car gods for weird stuff to keep coming at me hahaha.
So the abs rebuild folks said it very well COULD be that but that even with the part on their bench they wouldn’t be able to tell for certain. She at this point I think I have to toss a coin and either pull the trigger on the yaw sensor or the module rebuild. I hate shooting in the dark but at this point I think I have to just get moving forward. I’m gonna do some more poking around this weekend and choose a path by next week I guess.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Well, neither part is cheap if bought new. There are some salvage yard sites that sell at least the ABS controller reasonably cheap. Here's an example.
Well, neither part is cheap if bought new. There are some salvage yard sites that sell at least the ABS controller reasonably cheap. Here's an example.
So I’m leaning towards the yaw sensor. Does anyone have experience with what the readings should be when sitting still? I see brake pressure despite not pressing brakes (which I assume is normal) but the rotational and acceleration readings seem maybe suspect? I’m sitting on not perfectly level ground but the car is not moving at all.
From my research im thinking that sensor measures how fast the car is tilting, not just how level it sits. So im thinking the numbers should be reading zero or close to zero.
Im wondering about that steering angle. Is there a way to recalibrate it?
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Are the numbers static or changing while you sit still? (Sorry, but it is too cold, wet and miserable outside today for me to go check. Maybe tomorrow.)
There is an adjustment/calibration for steering angle, but maybe the steering wheel really is at 18°.
From my research im thinking that sensor measures how fast the car is tilting, not just how level it sits. So im thinking the numbers should be reading zero or close to zero.
Im wondering about that steering angle. Is there a way to recalibrate it?
ok that makes me think the sensor might be screwy afterall which kinda tracks. Especially the rotational speed reading.
steering angle would zero when wheel was dead straight but is very sensitive. I think the icarsoft has a calibrate for the steering but I haven’t gone into it to see what it entails
Are the numbers static or changing while you sit still? (Sorry, but it is too cold, wet and miserable outside today for me to go check. Maybe tomorrow.)
There is an adjustment/calibration for steering angle, but maybe the steering wheel really is at 18°.
they stayed static while still but moved when moving. I couldn’t really correlate though how they were moving much.
its sunny and 67 in south Texas so I’m getting projects done! 😄
Update: I replaced yaw sensor. It was pretty straightforward except for the fact that the hold down bolts were rusted 😡. One bolt snapped off. The other one the threads collapsed on. So I ground off the broken one and ran a new bolt through the floor pan and the stripped one I re tapped to a smaller size. The harness had been spliced and was kinda craptacular so I cut out the splice and re soldered the four wires. I cleared the codes and the readings seem more what you’d expect now. The hill assist definitely works more predictably now and only engages when on an incline and initial shakedown run everything felt good. So I turned the wife loose w it and I’ll kiss your *** 15 miles later they were dragging again. I checked codes and readings and everything was good. So I had her disable ESC and they didn’t drag the rest of her way.
So I think my next step is I’m gonna pull the seat again and leave the yaw sensor unplugged which from what I can find will disable ESC but not ABS. I’m gonna drive it a while like that. If they drag again, it’ll have to be brake hardware related and I’m thinking maybe the master cylinder will be the next thing I try. If they don’t, I think I’ll send off the ESC module to be gone through.
I’m also gonna check the MC cap to make sure the vent is working on it.
Any thoughts?
In the meantime, it looks like my VGT actuator crapped out on the Cummins so I gotta tackle that in the next week or so. The joys of owning high mileage vehicles….
01-02-2024, 06:25 PM
