Carole Cobb

Hello; Sure hope someone can help. I bought a 2008 GL450 from a reliable dealer ( I thought) $5000. later (after replacing Trans valve body, Intake manifold,, programming TCM, ABS rear wheel speed sensor, I could still hear a loud noise after the car was driven and warmed up. I replaced the cooling fan assembly. Didnt stop the noise! Realize now its the ABS pump located under hood drivers side. It comes on when the car is driven a short way and continues . It continues to run sometimes even when the motor is turns off (if it has been driven a long way ) It has never ran hot temp stays same. If i dont use the brakes very much it takes a little longer before it starts to run. It is a fairly new ABS It was replaced right before i bought it. Someone suggested I have the dealer bleed the ABS and brakes in case there was air left in. My Check Engine light comes on but goes off since i have bought the car. The tire pressure monitor shows active but after the noise starts it will flash inoppertable. The noise is coming from the ABS pump.Could anyone give me some advise as to what I can do? I would appreciate and thank you very much.

Max Blast

is your brake pedal constantly pulsating when this noise is heard?

Carole Cobb

Thank you for responding. No it doesnt't.

DarthVaderpa

I would recommend to replace all ABS sensors. If one sensor failed probably the other three will fail. In addition to ABS warning light and Engine Check on the dashboard plus your vehicle will go into LIMP mode and the transmission may no longer shift properly. That happened to me.

Max Blast

Have the computer codes read by a MB star DAS compatible tool and report back. Odds are your ABS pump is going crazy trying to react to implausible signals from one or more of your sensors.

a code rear will narrow down which corner to begin looking at.

it doesn’t sound like you’ve had the system opened so that air has gotten into it, but that is also a possibility - check the fluid level.

Carole Cobb

Thank you. I'll check them. Funny thing my ABS light has never came on. Check engine comes on sometimes if I drive long but then it goes away.

Carole Cobb

Ok thank you very much. The ABS pump box has been replaced ( i dont know when) because the box is still shiny while the connecting bolts are dirty metal color. The noise is coming from this pump box.

Max Blast

well, either it’s just a noisy pump and it will burn itself out one day or;

something is commanding it to run constantly and it will burn itself out.

you’ll need to have codes read to figure out what that something is in order to address the root cause.