ABS and ATC lights on dash

[Skier013]

2004 Windsor. I have ATC and ABS warning lights coming and going on the dash. How do I fix this? Coberg Oregon thought they had fixed them but they returned. 
Bruce

[Russ R]

On my 2003 Windsor, it is because of the ABS/ATC Board located in the FRB. It is no longer available. I have been told that it can be sent to KIB and be repaired. It looks like the picture that I attached. I have removed it and cleaned it and it works for a couple of months. Then it comes back on.

Edited November 19, 2023 by Russ R

[jacwjames]

X2 on the diagnostic board. 

It is there so you can run diagnostics on the ABS system.  Attached is a correction to the way you can retrieve fault codes.

Pretty straight forward but one thing to be careful with is not to hold the button down more then 2 seconds otherwise you will put the system in DYNO mode and won't be able to retrieve codes. 

Technically if you do put it in DYNO mode it should go back out of it when you drive it but in my case it did not.  I had a ABS stay on and when I checked fault codes it indicated it was in DYNO mode.  It would not come out.  After doing hours of searches and reading I found a procedure requiring two people, one in the drivers seat and one at the ABS module.  Had to follow the step by step procedure, wife in the cab pressing the bark pedal and me at the ABS module pressing the button.  Finally got the light to go out and made sure to never to hold the button down for more then a count of 2. 

A fault code is a two digit blink code.  If there are not codes it will give you a 1-1 blink.  If there is a fault you can do a search for ABS Bendix fault code and you can find info which probably be a downloadable manual.

Over the years I have had the ABS light come on.  One potential problem is that the ABS module needs a good ground to work, so I added an additional wire from the ground buss bar on the front fire wall and ground it to the module via one of the mounting screws. 

I have had a legitimate fault code, front drivers side wheel sensor out of spec, gap too wide.  So I pulled it and cleaned and pushed back in.  Drove it and the ABS light went out. 

 

 

abs_atc_system Monaco Addendum.pdf

Edited November 19, 2023 by jacwjames

[Bob Wightman]

On my 2004 Monaco Knight, when the ABS light comes on it is because the sensors on the rear wheel that reads the "Tone Ring" inside the brake drum is dirty.  This usually happens when the coach sits a lot and dirt/rust builds up on them and they won't get the magnetic pulse from the tone ring.   The sensor can be removed and cleaned or replaced without removing the wheel and drum, they pull out from the back side of the brake plate.  I had a shop take the wheels off and clean everything and check the brake pads at the same time, which fixed the problem.  From time to time since I've had the ABS light come on and it usually will go on and off during the trip to wherever I am going, then it just stays off.  The ATC light comes on every time I start the coach but goes out as soon as I step on the brakes.

[Happycarz]

One issue that has been talked about at length as a reason those lights coming on is that the fuel filters get restricted and cause an imperceptible engine stutter. You won’t feel it, in many cases, but the ECM does and interprets it as an ABS or ATC issue.

Many folks have fixed the light issue with replacing fuel filters.

[Skier013]

My ATC light will go off if I tap the brake while driving but comes back after a while. ABS comes and goes when ever it feels like it. After a stop and restart it will be off for a while.

I’m due for an oil change- I will look forward to the filter change fix. Thanks 

Bruce

[Happycarz]

It certainly would be nice if it were as simple as the fuel filters. Most of the occasions when the lights came on were when coach was under a load, like going uphill. 
 

Sometimes pushing the wheel sensor in, so it is closer to the tone ring,  also alleviates the lights.  You might try that remedy first, and go for a road test.  If you do both at same time and issue goes away, you will not know which one solved the problem. 

[jacwjames]

If you do have a ABS diagnostic module I try it next time you get an ABS light to come on. 

[Venturer]

On our new to us 06 coach, the ABS light would occasionally come on at startup. It would usually stay on till it was shut down. Then the next startup, it might be off. We checked the voltage drop at startup and noticed it dropped down to 9.5 volts till the engine started. That seemed to trigger the ABS light. When I held the battery boost button in, the voltage only dropped to 11.5 volts. I'm replacing two battery cables that had the bolt on ends with new cables with crimped ends. Hopefully, that will correct the problem.    

[Russ R]

Your ABS/ATC light should come on at start up and shut off when you reach air pressure and step on the brake.

[Venturer]

That's the way I thought it should work, however, sometimes it would not shut off. When plugged into the diagnostic at the rear, we could watch the low voltage (9.5v) when cranking trip the ABS fault. When reset and using the battery boost, the voltage did not drop below 11.4 and no fault was tripped.  Might just be coincidental, but time will tall as I've replaced the questionable battery cables. 

[Ivan K]

My ABS light comes on for a second when I turn ignition ON, runs a configuration self check, lamp check and goes out. That's also what I had to demonstrate to get an Air Brake endorsement. It stays ON if I had a previous fault code on a wheel sensor that I repaired because it can't confirm the repair while stationary. It goes out after few yards of driving if good. That's with a Bendix system.

[top flight]

Had the ABS light come on intermittently.  Inland Truck & Trailer (fantastic service in Thorold, Ontario), found right front brake needed bleeding.  Problem solved for very low cost.

[Georgia Mike]

My ATC light is on all the time it never shuts off. I thought that was normal but maybe there is a problem.

[jacwjames]

Go back to the post I did on Nov 19, I attached a document that explains the ABS and ATC system.

Do you have an ATC switch on the dash, wonder if it is on.

[Georgia Mike]

No the switch is off. The atc light has been on since I bought it two years ago. I thought I read somewhere that it was supposed to be on but now from what I’m reading it’s not. My abs light came on once while driving but shut off after a while and hasn’t come back on so I assume it’s ok. 

After doing some reading I see if the wheel sensors are defective or out of alignment it would cause the ATC light to come on but I would think the abs light would be on as well so I am thinking it’s something else since my abs light is off

[Ivan K]

Does the ABS light come ON for a second or two when you turn ignition ON? It should, for a lamp test.

[96 EVO]

On 11/20/2023 at 8:43 AM, Happycarz said:

One issue that has been talked about at length as a reason those lights coming on is that the fuel filters get restricted and cause an imperceptible engine stutter. You won’t feel it, in many cases, but the ECM does and interprets it as an ABS or ATC issue.

Many folks have fixed the light issue with replacing fuel filters.

Wow.... Who'd have thought!

Good 'head's up' Harry!

[Georgia Mike]

1 hour ago, Ivan K said:

Does the ABS light come ON for a second or two when you turn ignition ON? It should, for a lamp test

I haven’t looked for it specifically on startup being since there is so many that come on for a few seconds but I will look next time just to make sure the abs light IS working correctly.  Thanks Ivan, good place to start. I change all the fuel filters every year so I don’t think that’s the issue.

[Ivan K]

47 minutes ago, Georgia Mike said:

I haven’t looked for it specifically on startup being since there is so many that come on for a few seconds but I will look next time just to make sure the abs light IS working correctly.  Thanks Ivan, good place to start. I change all the fuel filters every year so I don’t think that’s the issue.

Yeah, because if the lamp was burned out and ABS not working due to a sensor for instance, ATC couldn't work either. Of course only one of possibilities. 

[jacwjames]

Do you have a way to recover/check for ABS codes??  It should be in your manual.

[Georgia Mike]

I found this in the owner’s manual about the atc light. I sounds like it’s saying it should stay illuminated at all times and blink when there is wheel slippage or when an event occurs. So I wonder if there is even anything wrong.
ATC Indicator Light:
During normal operation, the ATC indicator light will illuminate steady when the ignition key 
is turned ON. If an ATC event occurs, the indicator light will fl ash quickly. The indicator light 
will fl ash slowly if the ATC switch is activated. 

[96 EVO]

Can't say any vehicle I have owned with ATC normally went down the road with the lamp illuminated 🤔!

[cbr046]

1 hour ago, Georgia Mike said:

I found this in the owner’s manual about the atc light. I sounds like it’s saying it should stay illuminated at all times and blink when there is wheel slippage or when an event occurs. So I wonder if there is even anything wrong.

That's  *WITH*  the ATC switch on.  In the off position it will stay lit after engine start until the first application of brake.  Then it stays off for the rest of the voyage. 

You might pull an engine diagnostic.  There's a procedure in the manual (you have put a jumper on the diagnostic plug) or if you have a ScanGauge D . . . .

- bob

[96 EVO]

Ok, out of curiosity, I pressed the button in my SUV. Pressing the button turns ATC 'OFF'!

Lamp on the dash illuminates and reads 'ATC off'.