BAS ASR warning - PeachParts Mercedes-Benz Forum

graysilm · #1 02-18-2011, 05:23 PM

On my way home from work, my BAS ASR warning light and message appeared suddenly. I have not noticed any other symptoms. What could be causing this, and how expensive is this problem? Thanks.

graysilm · #2 02-21-2011, 10:26 AM

After reading some others posts, I see that this issue could be caused by a faulty brake switch. What is the brake switch? My brakes and brake lights seem to be working just fine, so this confuses me a bit. Thanks

Diesel911 · #3 02-21-2011, 10:35 AM

The Brake Switch is connected somewhere to the Brake Pedal. When you depress the Pedal the Switch is applied and your Brake Lights go on.
(In the old days on Brake systems with a proportioning Valve (switch) if you had a leak or air in one part of the brake system the proportioning Valve switch would apply and your brake light would go on. But, I do not think the all around disc brakes have that.)

I do not know about the newer cars but the older ones have wires going to the Brake Pads to indicate when they are worn out and there is also wires going to the Brake Fluid reservoir that I assume are there to let you know if the Brake Fluid is low.

If you have any sort of antiskid or antilock Brakes I guess there could be an issue with that.

graysilm · #4 02-21-2011, 12:05 PM

thanks. does anyone know how to troubleshoot this system?

Olivier · #5 02-21-2011, 03:21 PM

A low battery voltage will trigger this too.

whunter · #6 02-21-2011, 03:53 PM

If you need it.

DIY ASR Defeat Switch
DIY ASR Defeat Switch

.

TMAllison · #7 02-21-2011, 10:22 PM

Quote:

Originally Posted by Olivier

A low battery voltage will trigger this too.

Drive around with screen 24 on the CCU running and monitor voltage.

Key on, or start engine. Press and hold REST for five secs, change screens using AUTO L/R buttons.

KarTek · #8 02-21-2011, 10:40 PM

Are all four of your tires up to the proper pressure?

graysilm · #9 02-22-2011, 12:26 PM

Kartek, all of my tires are not inflated properly. I have a hairline crack in one of my front wheels and I have been adding air regularly. I plan on replacing this wheel soon. My car is not equipped with a tire pressure sensor. Do you think this could be causing the issue?

TMAllison, What is a CCU? Im assuming it is some kind of diagnostic computer. Where can I get one?

whunter · #10 02-22-2011, 12:39 PM

Quote:

Originally Posted by graysilm

Kartek, all of my tires are not inflated properly. I have a hairline crack in one of my front wheels and I have been adding air regularly. I plan on replacing this wheel soon. My car is not equipped with a tire pressure sensor. Do you think this could be causing the issue?

TMAllison, What is a CCU? I'm assuming it is some kind of diagnostic computer. Where can I get one?

YES, tire pressure has a direct impact.

The CCU = Climate Control Unit.

graysilm · #11 02-22-2011, 12:47 PM

I am going to check my tires and add the correct amount of air. After I do this, will I need to reset the computer? I don't have a obd tool, so can I disconnect the battery to do this?

graysilm · #12 02-23-2011, 11:34 AM

Update. After adding air to get all tires to proper pressures, the BAS ASR is warning is not coming immediately like it was. Now it comes on about 10-15 minutes into my drive. Very strange. This is getting annoying and i just want the warning to go away.

Question for TMAllison: What is screen 24 of the CCU?

KarTek · #13 02-23-2011, 12:12 PM

Here's my understanding of the way the system operates which may help your troubleshooting. Others may correct me where I'm not quite accurate.

The ASR system uses a steering angle sensor to provide input to the ECU. For a given steering angle, there's a table of allowable speed differentials for all 4 wheels. That way, if a wheel is out of spec, the system interprets that as a spin or skid and pops up a warning or sets a code if the condition is persistent enough. That's why tire pressure is important to proper system operation.

The steering angle sensor can be reset or re-calibrated but I can't recall the process. I think Terry knows. Hope this helps a little. (or more than a little)

graysilm · #14 02-23-2011, 04:11 PM

This issue is really annoying me. Does anyone know if there is a way to disconnect the warning feature of this system without causing any other problems? Thanks.

whunter · #15 02-23-2011, 08:03 PM

Quote:

Originally Posted by graysilm

This issue is really annoying me. Does anyone know if there is a way to disconnect the warning feature of this system without causing any other problems? Thanks.

You have e-mail again.

I hope it helps.