Turning Off the ABS Warning Light

[Jackm]

Last summer, one of our front calipers locked up on our W-20 chassis. A service technician came out and disassembled the caliper, lubed everything up and put it back together. When we arrived at our destination, we had all four brakes inspected by an authorized Workhorse shop to make sure that they were in good working order. As it turned out, the sticking caliper did not damage any of the brake components (i.e. the rotors or the calipers). Fortunately, when the lock-up occurred, we got off the road as soon as the ABS light lit up and prevented any real damage.

However, our ABS warning (Idiot) light is still on. Is there any way to turn the light off so that it can be used to indicate possible incidents in the future? Besides, I'm sick of looking at it since it reminds me of a very long day on the New Jersey Turnpike. Thanks in advance.

Jack

[DriVer]

Quote:

Originally Posted by Jackm However, our ABS warning (Idiot) light is still on. Is there any way to turn the light off so that it can be used to indicate possible incidents in the future? Besides, I'm sick of looking at it since it reminds me of a very long day on the New Jersey Turnpike. Thanks in advance.

Jack, You can pull out the sensors, clean and lube them and reseat them in the sensor holder. Oemtech's website I believe has that procedure documented.

In more times than not this corrective action will turn off the ABS lamp. If the ABS lamp remains on, a quick scan by a dealer can determine exactly which sensor(s) is bad and needs replacing.

With the lamp lit, the ABS is not working.

[max49]

Was it on when the WH svc cntr said 'all was well'? Did the heat damage the ABS sensor?

[Jackm]

DriVer,

I'll check out Oemtech's website for the details. Thanks.

Max,

I don't know specifically what originally triggered the ABS light. Since there was no visible damage to any of the primary components, I'm not if the ABS sensors were affected at all.

Jack

[Capt Joe]

Jackm,

I'm sure that the instructions will include the info that you need to drive the MH a little ways...a few hundred yards...for the computer to tell the ABS warning light to go out. If you only clean and lube them, it will stay on until driven and the signal is received that the sensors are seeing the little toothed part of the rotor.

If the light does go out and then comes back on, you may have a problem like I had on my 2nd brake failure (out of 3 I have had). The center part of the rotor where the teeth are that the sensor uses to determine the individual wheel speeds is thinner than the actual part of the rotor where the brake pads actually apply to stop the vehicle. In my case, while the heat generated was not enough to damage the thicker part of the rotor, it did get hot enough to warp the center part and moved the teeth out far enough to hit the ABS sensor and move it out far enough so it couldn't 'read' the teeth. After cleaning, lubing and reseating (an easy job btw) the sensors, the ABS light would go out after driving about 50 or 100 yards but after just a little more driving, it would come back on....I would reseat only to get the same results. The toothed part is an integral part of the rotor and the only way to fix it was to replace the rotor.....at MY expense, so far. I have submitted claims for reimbursement to WH for that invoice as well as one for my first failure but have not received anything yet.

Good luck and please report back as to your success.

Oh yes, if you have a good OHM meter, as in Volt/OHM, while you are cleaning, lubing and reseating the sensors, it is a simple job to check the OHMs on the sensors. I believe OEMY's site also has instructions on doing this. This can identify a bad sensor for you and after picking up a new sensor you could pop one in very easily.

[Jackm]

Capt Joe,

Thanks for then insight. I'm sure you brought up a possibility that few people are aware of. However, I'm hoping that it's just a matter of cleaning and lubing. I assume that the sensors incorporate a thermistor that yields a different value (of resistance) if and when its been overheated significantly. I'll try to chase down the details for checking the sensor with a VOM.

If the light does go out, we'll all be praying that it stays out. Otherwise, it looks like a new rotor. Thanks again. I'd be lost (and a lot poorer) without the folks on this forum.

Jack

[BEBOP]

MY abs light is one whenever I am in storage, or sitting in an RV park for a few days.
However once I start the engine and drive about 100 feet the abs light goes out until the next time it has been sitting for a few days. I have told the workhorse shop twice to check it but they just don't get to it as it always seems to have the last priority on the job work order and they apparantly don't schedule well.

[Jackm]

Nothing worse than a temperamental idiot light. I've encountered the same issue at many RV service shops. There's always a couple of items that invariably get dropped.

Jack

[DriVer]

There were times before I had my brakes repaired that my ABS light would set ON after startup. Once I got on the road and made a little headway the ABS lamp would go out.

During my repair we replaced all 4 sensors. Since then I haven't had an ABS indication. Fortunately the ABS sensors are not the most expensive thing on the brakes however there's no benefit or need to replace sensors if you can't ID which one may be bad.

[Bob (WA0MQE)]

Maybe someone can chime in here since my issue is also with the ABS sensors. For the first time at 24000 miles the ABS Light came on while traveling thru Texas. It was on for about 15 or so miles until I stopped at a campground. I shut the engine off while I set up for the night. After about 20 minutes I restarted and the light did NOT come back on. Due to the many posts on this forum regarding brakes I climbed underneath and checked each sensor and inspected the rotors. All seemed okay, except the left rear. I could see where it looked like the sensor had been nicking the cogs on the rotor. I pulled the sensor out, the end of the sensor was covered with a blob of grease, so I cleaned it and reinserted.

This brings up a couple of questions. One, when you push the sensor all the way in it bottoms out (on something). Is this bottoming out the sensor touching the cogs? Because of the nicking on the cogs I assumed it was so after bottoming out I backed the sensor back out just slightly.

Question two is: On Oemy's web site he mentions after cleaning then apply a little dab of lithium grease. What is the purpose of this grease? And, are you suppose to put the grease on the end as well as the sides?

We've continued on our journey and have traveled another 350 miles and so far the light has not come back on.

[DriVer]

Quote:

Originally Posted by Bob (WA0MQE) This brings up a couple of questions. One, when you push the sensor all the way in it bottoms out (on something). Is this bottoming out the sensor touching the cogs? Because of the nicking on the cogs I assumed it was so after bottoming out I backed the sensor back out just slightly.

There should be an air gap in between the face of the sensor and the rotor.

Wheel Speed Sensor Tone Wheels
Each Wheel Speed Sensor uses a tone wheel in order
to produce an AC voltage signal. Tone wheels are
metal rings with teeth (toothed ring) on the outside diameter.
The AC voltage is produced as the teeth pass through
the magnetic field of the WSS pole piece. The tone
wheels are attached to the rotor. Any imperfections in
the tone rings, such as a broken tooth or a missing
tooth, can cause an inaccurate wheel speed signal.

Quote:

Question two is: On Oemy's web site he mentions after cleaning then apply a little dab of lithium grease. What is the purpose of this grease? And, are you suppose to put the grease on the end as well as the sides?

Oemy will most likely reply to your question however this is what I have so far.

Installation Procedure

Important:

You may have to use the wire retainers
from the old wheel speed sensor wire on the new
sensor. Do not damage the new wire when installing
the retainers.

Important:

When the wheel speed sensor is fully
installed in the block bore, it contacts the tone ring
which is attached to the wheel hub. Normal bearing
play (0.001"-0.010") between the sensor tip and tone
ring in the wheel hub will move the sensor tip away
from the tone ring. This automatically establishes the
proper air gap.

1. Install the wheel speed sensor retaining clip
completely into the bore. The clip should stop at
the retaining tabs. Insert the wheel speed sensor
into the clip. The wheel speed sensor should
contact the tone ring.
2. Secure the sensor wire to the brake line with a
wire tie in the location noted during removal.
3. Connect the electrical connector

The wheel speed sensor installation does not specify the need for grease however I expect that a light coating of grease may facilitate the installation of the sensor in the holder. The face of the sensor should be kept clean so it doesn't offer a sticky surface for brake dust and dirt.

How's that?

[dieselclacker]

I believe the grease is for ease of installation, plus anti-corrosion between sensor and bore. I always used silicone grease on automobiles. As DriVer stated above, airgap between stator teeth and sensor should be between .003 and .010 inch. I always bottom the sensor out, then back out just a smidge. (thats about .005) Sounds like you found your problem with the placement of left rear sensor.

Dieselclacker

[-Gramps-]

Correct me if I am wrong but isn't it important to keep the surface of the sensors clean? I have read on other web sites (notably BMW cycles) that dirty ABS sensors can cause a spontaneous brake lock up and well result in death or injury for Cycle riders. If a lock up caused by a dirty sensor can happen with a motorcycle why not an rv?

[dieselclacker]

The sensors only function is to sense wheel speed and send that info to ABS computer. The computer releases brake pressure on a particular wheel before it locks up and begins to skid.
I would imagine that on a two wheel motorcycle ,if the rider has became dependent on the ABS, you would want to keep the sensors clean and functioning to avoid a lock up of either or both wheels. (especially that front one) yikes!!!!
I think some folks here are forgetting that the motorhome brakes function perfectly well with the ABS light on. It just means the brakes are capable of sliding the wheels. Granted if you have overheated and melted the wheel sensor, you can use the light as a warning signal, and you should check for overheated brakes if it does come on. I personally feel the sensor being knocked out of adjustment is probably the cause of the vast majority of ABS light events.



Dieselclacker