ABS Light

My 98 with 177K miles will illuminate the ABS light at intermittent times. Brake fluid has been flushed and topped off but it will still light up when ever it feels like it. Suggestions? Is there dirt on the sensors?

Pretty sure I read here as a first step that the sensors at the wheels can act up, be cleaned & sometimes works.

By far most ABS problems are sensor and sensor harness related, giving all kinds of problems. I am not surer about the values used on yhe 1998 model, only what my 1995 Transport has. I too had intermiitent ABS light. Each wheel has a 2 to 3 foot flexible harness from the wheel to the body, disconnect that jumper from the body harness, turn the key on but don't start the engine. You should read a voltage at each connector on the body side, for my 95 it was around 3.5 Volts. Then take an ohm reading on the jumper side, and for 95 it sould be 1800 to 2200 ohms for rear sensors, 800 to 1200 for front ones. I suspect you will probaly have an open there at one wheel. Diconnect the jumper harness and measure for continuity, and measure the sensor directly to see if it is the flexible wire has broken or shorted, or the sensor has gone bad.
good luck
Jeff

I'll start at the sensors and I guess I should see if I have any DTC recorded. It did set a CEL a few weeks back but it cleared itself.