ABS - Grunts When Doing A Self-Check

SOURCE:
Honda Service News March 2004

TITLE:
ABS Grunts When Doing a Self-Check

APPLIES TO:
1998-04 Accords, 1996-04 Civics, 1997-04 CR-Vs, 2000-04 Insights, 1998-04 Odysseys, 2003-04 Pilots, and 2000-04 S2000

SERVICE TIP:
Are owners of vehicles with a "compact" ABS complaining of hearing a short grunt or groan when backing or moving the vehicle forward after it's been sitting awhile? It could just be the ABS doing its self-check. A compact ABS has a modulator, a pump, and an accumulator all rolled into one. (Later model vehicles don't even use an accumulator.) The system is designed to do a self-check when the vehicle reaches a speed of at least 7 mph either forward or backward after sitting. So the grunt is normal; it doesn't mean there's a problem with the ABS. On some models, you'll even feel a vibration through the brake and accelerator pedals when you hear the noise.

You can show your customer just how this ABS self-check works by connecting the Honda Diagnostic System (HDS) to the 16P data link connector, and running the ABS function test. (This test cycles the ABS solenoid and runs the ABS pump.) The noise from the test may be louder than the noise made by the actual ABS self-check, but it lets your customer hear the noise and helps you to determine if the noise is ABS-related or coming from another source.