I have a 2000 HR Ambassador. On mine, the procedure to read out the ABS codes is to remove the ABS bulb from the instrument panel, then turn the key to the “ON” position, reinstall the ABS bulb and read the blink codes from the ABS bulb. There is about a 1.5 second delay between the first code digit and the second, then a about a 4.5 second delay before the code is repeated (or a second code stored).
I was able to get, online, a manual that explained the codes. The manual I got is available at www.meritorwabco.com/MeritorWABCO_document/mm39.pdf.
This manual is for my MH, so you might want to check which manual is applicable to your MH.
Hope this helps identify your problem.