Abs Sensor Replacement

[TheCoach]

Is it possible to remove and replace the rear wheel sensor without taking off everything down to the brake drum? This is the Meirtor Wabco pneumatic system I know the manual says that you are supposed to remove both rear wheels and the brake drum. It would appear that once you remove the rubber grommet and the spring loaded retainer clip that the sensor would come out. I know it sounds too simple but I just had to ask. :@

Thanks in advance
Robert

[TheCoach]

67Charger wrote:
My ABS light stays on for a few minutes when the engine is first started on my Freightliner XC chassis . It then comes on and off speratically. Would a sensor cause this . If so how could I tell which one?

If your system is a Meritor Wabco there will be a button located somewhere near the dash or in an exterior compartment The ECU itself will be either a frame mounted or an interior mounted unit. There are many different blink codes. Most contain three digits mine has only two. The best way to find out is to locate the serial number which will be located on the face cover of the ECU and then contact Meritor. They have very good customer support. Once the unit is identified you will be able to download an operator’s manual. From there it is very straight forward. As an example my error code was 4-4 which tells you that the problem is with the driver’s side rear wheel sensor. That problem can be anything from a sensor all the way to the point that the wire harnesses connects to the ECU. The abs light should only come on when you first start the engine and then stay off.

[dougmac]

67Charger wrote:
My ABS light stays on for a few minutes when the engine is first started on my Freightliner XC chassis . It then comes on and off speratically. Would a sensor cause this . If so how could I tectll whch one?

Do you know if you have Wabco ABS? If it is Wabco, it has blink code diagnostics that can direct you to the problem.

[67Charger]

My ABS light stays on for a few minutes when the engine is first started on my Freightliner XC chassis . It then comes on and off speratically. Would a sensor cause this . If so how could I tell which one?

[TheCoach]

mscamping wrote:
That's way different than ours and the ones I've changed.. That's a bummer.. Sorry for the miss info,sounds like a job for a truck shop, and I do mean truck shop, don't take it to an RV place.. Mike Mathews..

I'm to old to even think about doing that kind of job. I took it in yesterday and picked it up this AM. The cost was very high but they
have to jack up the entire MH so lots of labor

Total $458.00 to install a $14 part :M

[mscamping]

That's way different than ours and the ones I've changed.. That's a bummer.. Sorry for the miss info,sounds like a job for a truck shop, and I do mean truck shop, don't take it to an RV place.. Mike Mathews..

[TheCoach]

mscamping wrote:
No it is not necessary, I've changed many without doing that.. I go to NAPA and get a kit and crawl under and change.. They are in the backing plate for the brake on the inside of the dualls..Kit should have sensor with about 4' harness that just plugges into the harness on the chasiss..There'll be a round spring clip that you put into the hole before you install the sensor, take the old one out first, don't use it even tough it looks good.. Just follow the directions.. You need to run the coach, I think 10 mph to reboot the system to make the light go out.. Mike Mathews..

After many calls to Meritor and attempting to replace the sensor myself I discovered that my sensor is internal. The wire goes thru the rubber gourmet on the outside of the brake backing plate and continues inside to a holding clip. The sensor in angled at 90 degrees. End result required taking off both wheels and the brake drum. Part cost $14.00 labor $150.00

Lesson learned
Thanks to everyone for their help

[Nomadac]

dougmac wrote:
Here is an online manual:

Wabco ABS Service manual

Page 67 has a picture of the sensor and clip

Thanks for the website for the Service Manual.

[Nomadac]

dougmac wrote:
Here is an online manual:

Wabco ABS Service manual

Page 67 has a picture of the sensor and clip

Thanks for the website for the Service Manual.

[dougmac]

TheCoach wrote:
Do I put the sensor in the new clip before I put it in the hole?

The clip should stay in the hole. You will need a pick or something similar to pull it out. You will place the new clip in the hole before installing the sensor. If the clip is a problem to get out, consider just leaving it in the hole and reusing it. I have done this on occasion without a problem.

[dougmac]

TheCoach wrote:

dougmac wrote:
Here is an online manual:

Wabco ABS Service manual

Page 67 has a picture of the sensor and clip

I assume that the sensor holder is connected to the brake backing plate??

Thanks for the info for the service manual

The sensor shown on page 68 is mounted to the through the spindle and can be removed without taking the wheels off. If you have the arrangement shown on page 69, the wheels and drum need to come off.

[dougmac]

The 90 degree plastic piece that the wires come out of is part of the sensor. Pulling on that should pull the sensor out. Twisting it as you pull it out will help free it.

[TheCoach]

dougmac wrote:
Here is an online manual:

Wabco ABS Service manual

Page 67 has a picture of the sensor and clip

I assume that the sensor holder is connected to the brake backing plate??

Thanks for the info for the service manual

[TheCoach]

dougmac wrote:

TheCoach wrote:
Are all pneumatic sensors the same? I would assume that I would need my system number to get the correct part. The rear sensor is a bear to get to but I have had my arm up there and I think I can get it out.
Is it necessary to compress the sensor clip to get it out? If so that could be a challenge Please let me know

Thanks

The sensors I have seen are pretty much the same. The harness length may be different and I have seen different connectors also.

You don't need to compress the clip. They just pull out. Sometimes they can get stuck and it takes some effort to get them out.

How does the rubber grommet seat itself? I would assume that if I pull out on the grommet it will slide out on the wire. At this point will the sensor also slide out or does it require some force to free it from the sensor clip? . Do I put the sensor in the new clip before I put it in the hole? I know I have many questions but if I had these answers I think I would attempt the repair. The worst thing that would happen would be I might have to take it to Freightliner and have them install

Thanks Again for your help

[dougmac]

Here is an online manual:

Wabco ABS Service manual

Page 67 has a picture of the sensor and clip