ABS light on dash

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ABS light on dash

July 21, 2011, 07:06:29 pm

I know that the ABS light comes on when starting the engine but is it not supposed to go off after the engine is running? When I drove the MH yesterday the light stayed on. Only drove it about 5 miles. Did I do any damage? What would cause that to happen? Your input would be welcome. Thanks, Richard Bark

Re: ABS light on dash

Reply #1 – July 21, 2011, 07:30:07 pm

Quote from: rbark – July 21, 2011, 07:06:29 pm

I know that the ABS light comes on when starting the engine but is it not supposed to go off after the engine is running?

Richard,

The coach should go through a startup check and turn off the ABS light if everything is OK. Listen for the clicks, one per wheel. On our tag axle coach it's 8 clicks. If you don't hear one or more, the unit is not getting a signal from one of the sensors. If you don't wait for the clicks at the first ignition position, before the cranking position, sometimes that will cause the ABS light to stay on.

You can get the blink code by accessing the under-dash toggle switch. Barry's site has instructions on how to retrieve the codes and what they mean

ABS Troubleshooting

Our Wabco box is particularly cranky about bumpy roads, and several times we've had the ABS light come on with a fix simply being unplugging and replugging the connectors to the box. The Wabco box in our '03 is on the back wall in the streetside bay that houses the HWH aux compressor, inverter, 12V circuit breakers, and HWH control boxes. It's silver and says "WABCO" on it.

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When we've had a legitimate ABS light issue, it's always been one of the tag wheel sensors. The last time, Bob Irland at FOT rerouted the wiring so it wouldn't be under tension when the tag was raised.

No worries - you shouldn't have damaged anything.

Michelle

Re: ABS light on dash

Reply #2 – July 21, 2011, 11:22:08 pm

Steve and Michelle,
Thanks for the information. I think I didn't wait long enough before starting the engine.as it's too late now, I'll do the tests tomorrow. With your input and Barrys site for trouble shooting I should be able to figure it out. Thanks again.
Richard B

Re: ABS light on dash

Reply #3 – July 21, 2011, 11:26:50 pm

By the way, how loud are the clicks? It's not that I'm deaf, I just can't hear too well. All those years in an engine room on a boat does something to your hearing!

Re: ABS light on dash

Reply #4 – July 21, 2011, 11:32:29 pm

Quote from: Steve & Michelle – July 21, 2011, 07:30:07 pm

Quote from: rbark – July 21, 2011, 07:06:29 pm
I know that the ABS light comes on when starting the engine but is it not supposed to go off after the engine is running?

Richard,

...................The coach should go through a startup check and turn off the ABS light if everything is OK...............................

Michelle

Michelle,
Richard,
My ABS Warning light on the dash stays on, at each engine start, until the coach attains >5MPH. The FT Owner's manual reflects same.
Is that expectation different in later model years?
BTW, my ABS "clicks" are readily apparent, more apparent without a window open, because it's the ABS relays firing, that make the noise.
Neal

Re: ABS light on dash

Reply #5 – July 21, 2011, 11:45:21 pm

Hi Richard,
Our 1997 U 320 keeps the ABS light on after starting. It has never turned off until the coach is moving a few miles per hour. It has been that way for the past nine years. After a factory brake service/repair, on the rear brakes, the light would not go out. Bob Irland, and a huge pry bar, moved the sensor back in place. Never a problem since.

Raymond

Re: ABS light on dash

Reply #6 – July 22, 2011, 12:30:27 pm

Did some digging around on http://www.meritorwabco.com site and found the following

ECU Rev C : The ABS warning lamp comes on when the ignition switch is activated. The lamp goes out when the speed of the vehicle reaches approximately 4 mph (6 km/h). If the warning lamp remains lit or comes on at any other time during vehicle operation, it signals a malfunction in the ABS

ECU Rev D (started around 2000-2001): ABS lamp comes on at ignition momentarily for a bulb check, then goes out. If there is an Existing Fault the ABS lamp does not go out at ignition. If Lamp does not go out at speeds above 4 mph (6 km/h) — a fault still exists in the ABS system.

ECU Rev E (somewhere around 2010?) Same start-up as Rev D

I also read "In the event of a malfunction in the system, the ABS in the affected wheel(s) is disabled; that wheel still has normal brakes. The other wheels keep the ABS function." I always thought it turned off the ABS function completely so this was new information for me (read this in C,D & E revisions)

Re: ABS light on dash

Reply #7 – July 22, 2011, 04:03:09 pm

Steve,
Thank you. I've had that nagging question for some time and even looked at the Web Site, but never uncovered the info. I don't know why I didn't find the info before but, at least, now I know why various coaches display their ABS warnings differently.
Neal

Re: ABS light on dash

Reply #8 – July 22, 2011, 08:37:14 pm

Steve,
I have the Midland-Grau ABS system. My right front sensor was malfunctioning. Code .02, the chart is inside the box. Very convenient, plus the tech at MOT helped me out.
Thanks again!

Re: ABS light on dash

Reply #9 – July 04, 2012, 10:32:27 am

Quote from: Steve – July 22, 2011, 12:30:27 pm

I also read "In the event of a malfunction in the system, the ABS in the affected wheel(s) is disabled; that wheel still has normal brakes. The other wheels keep the ABS function." I always thought it turned off the ABS function completely so this was new information for me (read this in C,D & E revisions)

I saw this in a Motorcader magazine some years ago

My ABS light is on - Do I stlll have air disk braking?

Yes, when the ABS light on the dash is illuminated, the vehicle has all regular braking capabilities. Only the anti-brake skid feature is not operational. If your light stays on, contact a qualified service professional for repair as soon as possible.

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ABS light on dash

July 21, 2011, 07:06:29 pm

Re: ABS light on dash

Reply #1 – July 21, 2011, 07:30:07 pm

Re: ABS light on dash

Reply #2 – July 21, 2011, 11:22:08 pm

Re: ABS light on dash

Reply #3 – July 21, 2011, 11:26:50 pm

Re: ABS light on dash

Reply #4 – July 21, 2011, 11:32:29 pm

Re: ABS light on dash

Reply #5 – July 21, 2011, 11:45:21 pm

Re: ABS light on dash

Reply #6 – July 22, 2011, 12:30:27 pm

Re: ABS light on dash

Reply #7 – July 22, 2011, 04:03:09 pm

Re: ABS light on dash

Reply #8 – July 22, 2011, 08:37:14 pm

Re: ABS light on dash

Reply #9 – July 04, 2012, 10:32:27 am

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