Front brakes pulsing under acceleration
Thread Starter
Junior Member
Joined: Apr 2019
Posts: 45
Likes: 1
'03 CL55
Front brakes pulsing under acceleration
2003 CL55
Front brakes pulsing while accelerating, straight line or turning. Wheelspin or no, anything above about 1/3 throttle input.
No lights or warnings, no reduced engine power. Seems like only the front. More throttle input the harder the pulsing.
Not speed related, does it from a dead stop or rolling.
The sound is like when the ABS is activated. not subtle like the dsc.
No codes related to the abc, esp, dsc, bas, abs etc.
Thoughts ?
Front brakes pulsing while accelerating, straight line or turning. Wheelspin or no, anything above about 1/3 throttle input.
No lights or warnings, no reduced engine power. Seems like only the front. More throttle input the harder the pulsing.
Not speed related, does it from a dead stop or rolling.
The sound is like when the ABS is activated. not subtle like the dsc.
No codes related to the abc, esp, dsc, bas, abs etc.
Thoughts ?
Last edited by Hispeedlowdrag; Sep 26, 2025 at 02:06 PM.
Member
Joined: May 2020
Posts: 247
Likes: 57
From: Fort Worth
2005 CL55 AMG || 2005 CL65 AMG || 1989 560SEC
2003 CL55
Front brakes pulsing while accelerating, straight line or turning. Wheelspin or no, anything above about 1/3 throttle input.
No lights or warnings, no reduced engine power. Seems like only the front. More throttle input the harder the pulsing.
Not speed related, does it from a dead stop or rolling.
The sound is like when the ABS is activated. not subtle like the dsc.
No codes related to the abc, esp, dsc, bas, abs etc.
Thoughts ?
Front brakes pulsing while accelerating, straight line or turning. Wheelspin or no, anything above about 1/3 throttle input.
No lights or warnings, no reduced engine power. Seems like only the front. More throttle input the harder the pulsing.
Not speed related, does it from a dead stop or rolling.
The sound is like when the ABS is activated. not subtle like the dsc.
No codes related to the abc, esp, dsc, bas, abs etc.
Thoughts ?
Thread Starter
Junior Member
Joined: Apr 2019
Posts: 45
Likes: 1
'03 CL55
I was going to unplug the ABS fuse / relay but it seems like those do not exist. Looks like its all part of the dsc / bas / esp module ? Can't find anything to do with the abs itself.
Will try driving in dyno mode when I have the chance.
Will try driving in dyno mode when I have the chance.
Member
Joined: May 2020
Posts: 247
Likes: 57
From: Fort Worth
2005 CL55 AMG || 2005 CL65 AMG || 1989 560SEC
pretty sure ABS and all driving aids are turned off with dyno mode, double check that though. Maybe the flex discs (AKA "Giubos") are bad? That's all I got. Wheel hub maybe?
Thread Starter
Junior Member
Joined: Apr 2019
Posts: 45
Likes: 1
'03 CL55
The dash display says all those systems are disabled in dyno mode. I will try to disable the speed sensitive steering next, maybe its acting up. Then onto testing all the wheel sensors, yaw sensor etc. Fishing expedition.
Thread Starter
Junior Member
Joined: Apr 2019
Posts: 45
Likes: 1
'03 CL55
Pulled the #34 fuse for the ESP, BAS, ABS systems. Still get the pulsing, less than before but the car is in some kind of limp mode so reduced power. Coming through the steering wheel, not even sure its the front brakes anymore. This is getting weirder.
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Member
Joined: May 2020
Posts: 247
Likes: 57
From: Fort Worth
2005 CL55 AMG || 2005 CL65 AMG || 1989 560SEC
I'd jack up the front end and start checking for loose suspension components. Might be a ball joint, steering rod, wheel hub, etc. You can grab the wheel at the top and bottom once it's off the ground and jerk it back and forth like you're trying to wobble it off. you'll feel clicking or movement if something's loose. Do the same on the left and right of the wheel, pull with the left hand, push with the right, back and forth. left and right clicking is usually steering or wheel hub bearing, up and down is usually a ball joint or wheel hub bearing.
Might see what shops charge for diagnosis and take the $150-$250 dive to have them find the issue for you.
Might see what shops charge for diagnosis and take the $150-$250 dive to have them find the issue for you.
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Thread Starter
Junior Member
Joined: Apr 2019
Posts: 45
Likes: 1
'03 CL55
Unlikely it is suspension. I did check the front end, everything was good except the lower shock control arm bushings need replacing but even they aren't terrible.
This vibration is not speed related as in it doesn't matter if the car is even moving ( hard launch with wheelspin creates the same problem as going 30 mph with 50% throttle applied) and there is no problem under braking at any speed. Only happens under mid to heavy throttle application (25% or more).
Can't imagine what system is still at work when all the electronic aids are disabled.
This vibration is not speed related as in it doesn't matter if the car is even moving ( hard launch with wheelspin creates the same problem as going 30 mph with 50% throttle applied) and there is no problem under braking at any speed. Only happens under mid to heavy throttle application (25% or more).
Can't imagine what system is still at work when all the electronic aids are disabled.
