ABS Issues - 98 FDS

[florida egg]

I apologize in advance for the long winded question and my limited knowledge of RV systems.

I have a 98 36 foot FDS Alpine that is being serviced. Part of the service was to determine why my ABS light will not go off. Based on an ohm (?) test, the service technician found one of the rear ABS sensors to be defective and another one to be questionable. My extended warranty provider approved replacing the defective sensor but not the questionable sensor. Replacing the defective sensor has not corrected the problem. I have been told that the ABS light is still on (after driving over 5 mph) and the ABS system is not operating. The extended warranty provider has told me that they will cover replacement of the questionable sensor IF it corrects the problem. If it does not correct the problem I will have to pay for it (~$300) out of pocket. The service technician believes it will correct the problem but would like to "plug his computer" into the ABS system to run a diagnostic to determine if there are other issues. He has not been able to find the "ABS diagnostic port" to plug in his computer. Is there an "ABS diagnostic port" on the 98 model? If so, is it suppose to be located under the dash by the steering column?

Thank you in advance for your assistance.

[Algoma]

There is no diagnostic port on the Type C ABS ECU, which is the one you have. A special cable and test unit is needed to test the ECU which no one has. I can send you a copy of the manual (PM me your email address) which shows you how to do some diagnostics with a switch (not installed by WRV). My insurer would not pay for a new ECU without proof and I would have been out $1400 if that proved not to be the problem. I gave up, removed the ABS bulb and have never been bothered since.
FWIW the ECU is in front of your left foot and the side panel has to be cut back to remove it. The test connector is behind the cover below the transmission selector.

[jetar]

There are a couple of other things it could be. First and I assume the technician did this, the sensors can be removed easily and cleaned so that can "read" the lugs turning on the wheel that they sense off of. I believe it is posted on the forum about this if you search the alpine site. Second, the lugs can get dirty and may need to be cleaned so that the sensor can "read" the rotation. Regarding this I found that I had a rear axle seal leaking on my 01 and this coated the inner left rear wheel which then picked up dirt and made the lug rotation unreadable by the sensor. These may not be your problem, but something to consider.

[Alpine Dave]

The ABS light on my 1999 Alpine would not go out. I discovered that the sensor slots on the rotors were rusted badly enough that there was not sufficient magnetic coupling for the sensor to get a strong enough signal to determine the rotation speed. I replaced the rotors (for other reasons) and ABS light went out the first time I drove the coach.

[Tom and Patty]

$300 dollars?
We had to replace a sensor and the cost of the sensor was around $50.

It is pretty much plug and play.