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heybc2 · 06-10-2023, 10:23 AM

2004 Dutch Star Spartan Chassis getting intermittent ABS light. Scanguage says open circuit or low voltage. Happen twice so far. First time we were stopped at a rest area and did not shutdown. Light came on while pulling out of parking spot and went out after braking once. Second time came on after start-up while pulling out of campsite and stayed on until shut down and restart. Any ideas on what to look for?

Skip426 · 06-10-2023, 10:53 AM

ABS light can be a poor connection at one of the wheel speed sensors ; and your issue being erratic sounds like just that.

ABS Module requires a special diagnostic program and not all code readers have it , checking the module for codes when the light is on is the only way to narrow the problem down.

prafersno · 06-10-2023, 10:54 AM

two thoughts:

It sounds like it happens when you are turning, so I would thoroughly inspect the wires near the front wheels. Unplug and inspect contacts for corrosion. Also, make sure there's no tension near the plugs when you turn.

On cars/trucks, this occurs when the wheel bearings(hubs) start to wear and have play or 'slop'. Chamber (side to side) forces change when turning and the gap between the ABS sensor and the stator ring can go out of tolerance, causing an intermittent signal loss. On a big chassis, I don't think this would happen except at parking lot speeds when turning.
The simple test for this is to lift the front wheels, hold top and bottom, push/pull to see if there is any play/slop.

Good Luck!

mackwrench · 06-10-2023, 03:02 PM

Just fyi, but abs light will not affect brakes working, only keeps the tires from locking up on hard/panic stops. I've had vehicles towed to shop for ABS light on...nor will it cause engine shutdown.

The system goes through a self test every time you switch key on, that's the series of clicking you'll hear before engine starts. It cycles the air valve solenoids and pistons.
The open / low voltage is saying a wheel speed sensor was not functioning, sometimes the light will go out as soon as the wheel rolls ..

The air brake ABS system is very simple. As Skip posted, Your intermittent ABS light probably is you have a wheel speed sensor that's out of adjustment, meaning it's too far away from the sensor ring, or you have a sensor cable connector issue.....or as posted, a bad wheel bearing.
If it was a control module or an air valve, usually the light is on all the time.

With our a scan tool to see DTC or live sensor Data, it's all a guess.

But if you're comfortable crawling under coach, the wiring harness is probably zip tied to the brake chamber air supply hose, you can follow the harness to the sensor, use a screwdriver try and push the sensor inward toward the wheel hub... it'll touch the tone ring, also following the harness the other direction, it'll plug into the control module usually located in frame cross member above axle. Probably not easy access.

Jake21 · 06-11-2023, 02:38 PM

Not meaning to hijack, but how do you remove the sensor? I need to replace mine. Do they just pull out?

mackwrench · 06-11-2023, 03:56 PM

Quote:

Originally Posted by Jake21

Not meaning to hijack, but how do you remove the sensor? I need to replace mine. Do they just pull out?

Yes, the sensor is held in with a round spring clip. If it's a front sensor, You maybe able to turn the wheel sharp to access it. Rears are fairly easy to see.
It'll have some resistance but it'll pull out. Sometimes there's enough of it to pull on with a pair of pliers.
A shot of penetrating spray will help.
A quick search on YouTube will get some results...

mackwrench · 06-11-2023, 03:58 PM

Sensor stock photo

Click image for larger version

Name: shopping.jpg
Views: 17
Size: 10.9 KB
ID: 395094

Jake21 · 06-11-2023, 04:04 PM

Quote:

Originally Posted by mackwrench

Yes, the sensor is held in with a round spring clip. If it's a front sensor, You maybe able to turn the wheel sharp to access it. Rears are fairly easy to see.
It'll have some resistance but it'll pull out. Sometimes there's enough of it to pull on with a pair of pliers.
A shot of penetrating spray will help.
A quick search on YouTube will get some results...

Cool. Thanks.

Jake21 · 06-11-2023, 04:05 PM

Quote:

Originally Posted by mackwrench

Sensor stock photo Attachment 395094

Yep. That is what i am replacing. Thx

Ray,IN · 06-11-2023, 09:24 PM

FWIW, when we bought this MH the ABS light was on constantly. I asked my auto mechanic about it and he said to KISS -keep it simple stupid. He told me to use my pressure washer to clean the backside of each wheel from the opposite side with the straight stream washer.
I did and it worked, it cleaned out the slots in the tone ring that the sensor detects. Ever since the ABS light only comes on at initial key on self-check.