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Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3663
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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I have a 2002 mercedes ml 320 and there is a warning

Customer Question

i have a 2002 mercedes ml 320 and there is a warning triangle in the center of the dash when it came on it tried to apply the brakes and the ESP/BAS light came on i took it to a german automotive shop and they had it a week and said they could not get the light to come on and said that it showed no codes so they didn't charge me the owner said that usually when the ESP & BAS light comes own you have a bad brake light switch so i bought a brake light switch and installed it and the light still not go out till after about 5 miles of driving but after about 13 mile of driving
JA: Have you checked the dashboard control switch? Have you checked the fuses?
Customer: after 13 miles of driving the BAS/ESP came back on and won't go off
JA: Are you hoping to fix this yourself?
Customer: yes i have a snap-on verus scanner that checks for ESP/BAS problems but it showing no codes just as the shop said
JA: Great! What have you tried so far?
Customer: i have replaced the brake light switch was i said before the auto shop said that it showed no codes and to confirm that i hooked my scanner to it also i also looked at the voltage and wave pattern on the wheel sensors
JA: Is there anything else the Mercedes Mechanic should be aware of about your Mercedes?
Customer: no thats the only problem i have had in the 14 years i have owned it
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Mercedes Mechanic about your situation and then connect you two.
Submitted: 4 months ago.
Category: Mercedes
Expert:  Lou P. master tech replied 4 months ago.

Hello. If you have a esp/bas light on there will be a code. The scanners you are using and the shop is using must not be able to retrieve the codes. You need to get a star diag machine. The only instance I have ever seen this is when there is a bad ground at the ground lug behind the drivers side headlight. That was common to rust and break. That is about all you could check. I had this happen to me personally but the warnings only came on when the car started moving above 15 mph. Drove me crazy lol. But again other than that you need access to a star diagnosis machine. Lou.

Expert:  Lou P. master tech replied 4 months ago.

Also when you install a brake light switch they need to be adjusted. You start by pulling the center plunger out all the way and press the brake pedal down and while holding it down insert the switch and lock it down then release the brake pedal. You will hear the switch click and self adjust. Never pull the brake pedal up or it will go one click too far. Hope this information helps. Get a code with the star diagnosis machine and I can assist. Lou P.