128i ABS Issue - Triple Lights

[rivesalex21]

Hello all,
Recently I've undertaken a project that involved removing the rear subframe, and replacing all the suspension components with new parts (except the springs), and replacing all other parts with something that is not oxidized. The rationale behind this is that I'll have a car that is refreshed, and a secondary, fully built subframe that I can sell off to recover some of the costs.

The following have been replaced:
Subframe - Used
Differential (3.73) - Used
Left and Right Driveshaft - Used
Shocks - New
Control arms and Trailing Arms - New

Pics attached

However, it seems that the rear left wheel speed sensor is causing an issue, and I am trying to find out what is causing it. Here are a couple of things I've noticed:

Codes:
5DC1 -

- The lights go away if reverse the car, and drive under ~15 mph.
- Driving between 15-20 mph causes the lights to show at different speeds, the gear I'm in doesn't matter
- Driving over 20 mph definitely causes the lights to show up

- I monitored the car using INPA and found that all four wheel speeds are consistently very close to each other, but the rear left dips sporadically, I could be driving 15 mph and the speed drops to 8 and right back up to 15. The higher the speed, the more drastic the drop.

- With the car jacked up, and with codes cleared driving past 10 mph or so causes the DTC to kick in and attempt to stop the rears. Disabling the DTC and driving past 15 mph will cause the codes to flick on again.

- The last thing I noticed is that the ABS ring on the left rear axle is a little banged on one of the notches. I added two pics that show the condition. I'm not sure if that would be enough to mess up the readings


So to me it seems that the sensor is not the issue, but the readings the DTC gets. I hope it is not electrical, and just an issue with the ABS Ring.

Has anyone been through something like this before? Can you share your experience? Through this project I've learned it is sometimes better to pull back a bit before doing something stupid.

Thank you for reading!

[Papa Popov]

The left rear ABS sensors are notorious for failing on these cars due to contact with a component (that I can't think of off the top of my head). Mine took a dump around 115k.

Unless there's something seriously whack going on with your car your best bet is just replacing the sensor. If that doesn't work you can just return it (don't forget to sign up for PayPal's free return shipping program if you buy online).

[rivesalex21]

Originally Posted by Papa Popov

The left rear ABS sensors are notorious for failing on these cars due to contact with a component (that I can't think of off the top of my head). Mine took a dump around 115k.

Unless there's something seriously whack going on with your car your best bet is just replacing the sensor. If that doesn't work you can just return it (don't forget to sign up for PayPal's free return shipping program if you buy online).

Problem is that placing the rear left sensor on the rear right works without issue. I end up having the same issue where the wheel speed readings are consistent, but drop sporadically... That is why I think its either the ABS ring, or a problem with the DTC unit/wiring-electrical issue, which I really hope is not the case.

[Pistolpete2911]

Your last picture shows that the ring is not Ok anymore.
I´d change it.

[rivesalex21]

[QUOTE=Pistolpete2911;29128670]Your last picture shows that the ring is not Ok anymore.
I´d change it.

I agree, I had some free time today to remove the driveshaft and its ABS ring. Tomorrow I may receive a new one (theyre only 10 or so dollars) and I'll install it and see if anything changes.

[rivesalex21]

After changing the ABS Ring the lights went away. DCT and Brake light remained on and left after doing a steering angle sensor calibration through ISTA , not INPA.