special service message 15747

[ocbaud]

15737
A Mechanical Noise (Buzz, Growl, Scraping, Zip) May be heard on drive away after initial start-up.
Some 1992-2002 vehicles equipped with anti-lock brakes may exhibit a mechanical noise (Buzz/Growl) on drive away after initial start-up. Each time the vehicle is driven. As vehicle speed reaches approximately 11-32 KM/H (7-20 MPH). The anti-lock brake control module turns on the pump motor and valves for approximately one half second. At this time a mechanical noise (Buzz, Growl, Scraping, Zip) maybe heard. This is a normal function of the self-check by the anti-lock brake control module for additional information refer to workshop manual section 206-09.


anyone have any more info on this? my car has this problem and it kinda gets annoying. It not only makes the sound, but you feel the brake pedal pushing back at you when it does it along with the headlights dimming

 

[sgarlic]

What the message describes is normal. Sounds to me like you've got a weak battery or bad alternator as well.

My Jeep ZJ also states a similar thing (about the ABS self test thing) in the owners manual.

 

[ocbaud]

What the message describes is normal. Sounds to me like you've got a weak battery or bad alternator as well.

My Jeep ZJ also states a similar thing (about the ABS self test thing) in the owners manual.

so when it makes the testing sound, its normal for the brake pedal to push back while pressing it?

 

[wannabe2000GT]

mine does that sometimes at low speeds. i was also gonna say that my jeep says the same thing in the manual. id say its a pretty normal thing to happen since both my vehichels do it.

 

[sgarlic]

Depends I guess on what your defintion of normal is. Normal to me would be a momentary thing.. if it's doing it for several seconds, or affecting your braking real badly, then perhaps there's something else going on.

 

[ocbaud]

Depends I guess on what your defintion of normal is. Normal to me would be a momentary thing.. if it's doing it for several seconds, or affecting your braking real badly, then perhaps there's something else going on.

yeah, its momentary. just does it usually within the first 2 minutes of driving at very low speeds(coming to a stop)

this is my first car with abs, so maybe i'm just not used to it.

 

[d90212]

Principles of Operation

The anti-lock brake system (ABS) module receives wheel speed readings from each wheel speed sensor and processes this information to determine if an ABS event is necessary. The wheel speed sensor electrically senses each tooth of the wheel speed sensor indicators as it passes through the wheel speed sensor's magnetic field.

The ABS module continuously monitors and compares the rotational speed of each wheel, and when it detects an impending wheel lock, modulates hydraulic brake pressure to the appropriate brake caliper. This is accomplished by the ABS module triggering the hydraulic control unit (HCU) to open and close the appropriate solenoid valves. Once the affected wheel returns to normal speed, the ABS module returns the solenoid valves to their normal position, and normal (base) braking resumes.

The ABS module is self-monitoring. When the ignition switch is turned to the RUN position, the ABS module will do a preliminary electrical check, and at approximately 12 km/h (8 mph) the pump motor is turned on for approximately one half-second. Any malfunction of the ABS will cause the ABS to shut off and the yellow ABS warning indicator to illuminate, however, normal power assisted braking remains.

The ABS module has the ability to store multiple DTCs in memory.

- why not read the service manual as well since you have the SSM

 

[merc123]

i've never heard this.