|
gelenda
Veteran
Date registered: Mar 2012
Location: Great Bay, New Hampshire
Vehicle(s): '03 G500, '16 E63S AMG, '15 Grand Cherokee Diesel
Posts: 122
| Brake lights always on
Even after disconnecting the battery for a while, as soon as I turn the key into the 2nd position (without actually starting the engine), the brake lights come on and I get a dash warning message "Brake Lamp Visit Workshop". This happens without pressing the brake pedal at all.
I replaced the brake light switch behind the brake pedal (twice!), and tried re-seating it a bunch of times, but is there another switch somewhere that controls the brake lights?
Also, I noticed one of the hose clamps on this thing was broken so I replaced it, but I don't know what it does or if it's related to the brake pedal.
 (IMG_0878.JPG)
Attachments
----------------
 IMG_0878.JPG (39KB - 1 downloads)
|
|
| |
|
Floobydust
Veteran
Date registered: Mar 2014
Location: Massachusetts, USA
Vehicle(s): 1995 E320 Cabrio, 2003 G500, 2000 SL500, 1980 TR8
Posts: 284
| RE: Brake lights always on
Do you have a trailer hitch and trailer light plug? If so, check the plug for corrosion and the wiring harness for damage. A cross connection here will back feed the brake lights and trigger an error at the SAM. You can also disconnect the trailer light harness I the compartment that holds the CD changer just to be sure.
I don't think it is the brake light switch because if that were stuck on, the engine would cut back power (e.g., the "Audi" function to prevent union tended acceleration).
If it's not these, I would suspect a bad rear SAM.
|
|
| |
|
gelenda
Veteran
Date registered: Mar 2012
Location: Great Bay, New Hampshire
Vehicle(s): '03 G500, '16 E63S AMG, '15 Grand Cherokee Diesel
Posts: 122
| Re: Brake lights always on
Funny you should mention the trailer hitch because I reached the same conclusion.
I re-installed the brake light switch again and now the dash warning message is off but the brake lights are still on. Then I thought about the trailer wiring which the dealer installed for me when I bought the truck more than 10 years ago. I went to check the fuses for the trailer, which there should be 2 (#17 and #18). Well, my truck doesn't have fuse #18 which is the trailer socket fuse. Maybe the dealer forgot to install it...
I'll try disconnecting the harness to see if that makes any difference. Thanks!
|
|
| |
|
fernweh
Date registered: Apr 2006
Location: Calabasas, CA - Centenario, BCS - Luebeck, Germany
Vehicle(s): Few Mercedes-Benz, a Toyota Amphibious and a Vespa
| RE: Brake lights always on
Does the "third" brake light in the rear door, is lit as well?
That light is on a different circuit than the brake lights in the tail lights, right and left.
It could not being "back fed" from a problem in the trailer harness.
If all three brake lights are on, the problem could be the rear SAM or a CAN bus communication fault (brake switch/wiring) |
|
| |
|
gelenda
Veteran
Date registered: Mar 2012
Location: Great Bay, New Hampshire
Vehicle(s): '03 G500, '16 E63S AMG, '15 Grand Cherokee Diesel
Posts: 122
| Re: Brake lights always on
Yes, all three brake lights are on.
I disconnected all that trailer related stuff behind the CD changer but the lights are still on.
It doesn't make any difference if the brake switch is plugged in or not. From the wiring diagram it looks like the switch is wired into the SAM and the ESP control module too. If I turn the engine on I get ESP/ABS/BAS warnings instantly, like it's a stored code that won't go away.
Is it possible the ESP control module in the passenger footwell is fried? Swapping out the rear SAM probably requires removing the center console. I already cut a bigger hole in the rear SAM opening in the center console to check relays but the passenger seat is in the way.
|
|
| |
|
fernweh
Date registered: Apr 2006
Location: Calabasas, CA - Centenario, BCS - Luebeck, Germany
Vehicle(s): Few Mercedes-Benz, a Toyota Amphibious and a Vespa
| Re: Brake lights always on
gelenda - 3/22/2015 6:35 PM
Yes, all three brake lights are on.
I disconnected all that trailer related stuff behind the CD changer but the lights are still on.
Yes, I was afraid of that.....
I had discovered a faulty SAM in Harald's truck some time back. One of the brake lights would not work. Traced the wiring all the way back to the SAM - nada.
Finally rigged something up, to get all three lights working.
"Swapping out the rear SAM probably requires removing the center console" It is more than "Probably"......it's called "commitment"!
Clear the playing field, and take both seats out, and start by remove one item after the other. Everything is indexed nicely, can't mix it up.
Good luck to you.
Edited by fernweh 3/23/2015 4:05 PM
 (IMG_3879.JPG)
Attachments
----------------
IMG_3879.JPG (241KB - 1 downloads)
|
|
| |
|
gelenda
Veteran
Date registered: Mar 2012
Location: Great Bay, New Hampshire
Vehicle(s): '03 G500, '16 E63S AMG, '15 Grand Cherokee Diesel
Posts: 122
| Re: Brake lights always on
Wow, unbelievable that they put so much vital electronics in a place that requires ripping apart the interior of the truck to get to. There is that lateral acceleration sensor module which sometimes goes bad too. Meanwhile the stupid CD changer is like 4 screws and you're done.
There was definitely something weird going on with the SAMs though when I got the truck back from the dealership a few weeks ago after they fixed a power steering hose that leaked. The left low-beam bulb wouldn't come on at first and the passenger door lock now doesn't work. Then when all this brake-related stuff started happening a week or two later, I had trouble with one of the rear windows, and even the speedometer stopped working for a short while. It just feels like the CANbus is falling apart in the truck. All these different things failing in different parts of the network in such a short period of time.
EDIT: I was able to scan a new code that I didn't see before, this time it's P1817 "back (reverse?) light component short circuit to positive"
Edited by gelenda 3/23/2015 4:38 PM
|
|
| |
|
gelenda
Veteran
Date registered: Mar 2012
Location: Great Bay, New Hampshire
Vehicle(s): '03 G500, '16 E63S AMG, '15 Grand Cherokee Diesel
Posts: 122
| Re: Brake lights always on
I didn't have time to play with it anymore so I took it to a mechanic and he said its the ESP control module located in the passenger footwell (part 4635451632). I looked around and its a part that's between $1250 and $1800 new depending where you look. Any chance of finding this thing used somewhere or getting it rebuilt? |
|
| |
|
AlanMcR
Expert
Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
| Re: Brake lights always on
Find out if it needs to be coded to the vehicle. If not, plead for a parts swap with someone with a known good one.
|
|
| |
|
gelenda
Veteran
Date registered: Mar 2012
Location: Great Bay, New Hampshire
Vehicle(s): '03 G500, '16 E63S AMG, '15 Grand Cherokee Diesel
Posts: 122
| Re: Brake lights always on
Yeah I think it needs to be coded. There are different hw/sw versions depending on the year.
Basically the car will not function properly if this module goes bad. On the way to the shop I got a "differential lock active" message on the dash for a moment. Another symptom I got earlier is the transmission going into limp mode. |
|
| |
|
gelenda
Veteran
Date registered: Mar 2012
Location: Great Bay, New Hampshire
Vehicle(s): '03 G500, '16 E63S AMG, '15 Grand Cherokee Diesel
Posts: 122
| Re: Brake lights always on
So the problem turned out to be a corroded ESP control unit found in the passenger footwell. Apparently the windshield was leaking a bit on that side and water got into the connector, causing the ESP module to totally malfunction. Something worth checking, I guess, to avoid costly repairs.
Also, there might have been a small drip from the heater core that could have contributed.
Edited by gelenda 9/23/2015 10:26 AM
|
|
| |
|
atg
Veteran
Date registered: Nov 2014
Location: Los Angeles
Vehicle(s): 2005 G55, 1985 300tdt
Posts: 129
| Re: Brake lights always on
I have the inverse problem, and it is intermittent.
I get the "brake light - drive to workshop" warning. The brake lights flicker but then go out.
If I turn the truck off then back on, light goes away, all three brake lights work fine. For awhile. Then warning light comes on again.
Seems like maybe the ESP, although I have not replaced the switch yet, mainly because I cannot find the part number, and it is saturday night and the dealer would not stay open an extra five minutes for me to pick up the new switch!
Ideas welcome. I see some later 2008-9 E-class cars had problems with the switch and this warning came on. Hoping it is that.
K |
|
| |
|
atg
Veteran
Date registered: Nov 2014
Location: Los Angeles
Vehicle(s): 2005 G55, 1985 300tdt
Posts: 129
| Re: Brake lights always on
Switch is P/N A 001 545 64 09 per startek for my 2005 g55. |
|
| |
|
DUTCH
Administrator Doppelgänger
Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
| Re: Brake lights always on
Any chance it might be as simple as bulb(s) loose in the socket(s), building up a bit of heat due to the poor connection and opening the circuit? |
|
| |
