ESP - BAS - ABS Locked in Park

[Lozzar]

also, does this model have the cable release from brake pedal ?
Not being cleaver, just read it somewhere in the past.

Yes, the Foot Pedal puts the 'Handbrake' on and a Handle near the Door releases it.

 

[joderest]

No, you mis understood, I read somewhere some time ago that some Mercedes have a cable release from footbrake to gear selector, hence stopping shifting lever to drive with out foot on the brake, if your vehicle has one and it has snapped or something else, would prevent shifter moving.
Of course, may just have been older Mercedes, i am not sure.

 

[joderest]

Oh, and ir brakes anything like my 2003 ML, the footbrake operates brake linings contained within the disc, not on the rear brake pads, hence they are separate systems, not linked in any way.

 

[Lozzar]

Oh, and ir brakes anything like my 2003 ML, the footbrake operates brake linings contained within the disc, not on the rear brake pads, hence they are separate systems, not linked in any way.

Yes I sensed the Foot operated Handbrake had 'Shoes' inside the Disc drum because the car motions forward (or backwards) when you apply it and then release main brakes with the main foot pedal. I'll look for a cable to the gearbox selector but i have stripped this area of all carpets and even removed the accelerator pedal and i think i would've noticed a cable doing this job but i wasn't looking for it so I'll take another look. I felt i needed to see as much as i can in the foot well, especially the wires that go into looms across the back of the dash board and down the channels at the side of, and under, the drivers seat. All this area is thankfully very dry so i don't suspect water or damp has contributed to these issues. Thanks for suggestions.

 

[Lozzar]

Done the Front ABS Sensors no change. Checking the connectivity and resistance of the rear sensors next. Thought I'd change the focus to the CAN Bus. Done a lot of research and felt comfortable attempting to trace the connectivity resistance of 60 Ohms on the Bus system (2 x 120 Ohms in Parallel) and then I was going to check the Can High Voltage (v2.5/v3.5) and the Can Low voltage (v1.5/v2.5). Both of these checks use the OBD Pins 6 & 14. Tested the OBD Battery voltage on Pin 16 using ground at Pins 4 & 5 and that's ok. However when I came to use Pins 6 & 14 I couldn't understand the absence of the Ohms reading or a Voltage reading. Closer examination of the OBD connector on the Car shows no wire connected to Pin 6 !!!! See attached images of the connector on the car. CAN (no pun intended) anyone explain why no Pin 6 wire? How does a Scanner compensate for this? I Purchased the "iCarsoft MB V1.0", it was a recommended scanner from Diagnosticworld.com for MB Cars. Do MB bespoke scanners take account of Pin 6 being missing and the Bus uses a different PIn?
Every video and file I have looked up point at pins 6 & 14 as the Can High & Can Low pins.
Has anyone got an answer to this anomaly?? My next stop is to contact MB Stratstone in Leeds for an explanation but I'm not sure they are obliged to help me?
Regards All.

 

[Lozzar]

CL500 2092 W215: I contacted MB Stratstone by telephone about my OBD connector. The lad who answered sought advice from one of the Master mechanics and he offered the explanation that the wire will not have been removed, if it's not there it never was. I can confirm that the wire loom going into the connector looks intact and correct. So this would suggest that there isn't a "Bus" as such, instead a series of individual control modules.??
Another question I have is about the Fuse Box on the driver side (RH Drive). When the Ignition is turned there is the sound of a Fan coming from the fuse box. Is this normal? Is there something in there keeping two modules cool??
Appreciate any info.
Cheers

 

[joderest]

most large fuse boxes/relay boxes have a small fan to keep everything as cool as possible.

 

[mattkh]

Appreciate any info.
Cheers

I wish I had seen your post earlier. Your thread has been very inspirational to me.
The answer I have is :
There can be some CAN bus designs that use only ONE wire. In your case it is using the low voltage line Lo.

 

[Lozzar]

Wow, thankyou for that. I'll re-investigate that tomorrow, at least I'll be able to test the Can Low voltage which may tell me the health of the Can circuit. The temperature is dropping now so it will be tomorrow now. My next target is to examine the ABS pump electrics. See if theres anything obvious like corrosion. Struggling to get clearance to one torque screw because the power steering chamber is in the way. and the bracket holding it has such a long screw thread above the nut my small sockets dont cover the hex nut, they foul on the crazy long thread?? I'll buy a socket to do the job tomorrow. Clearly its something between the ABS pump, the ESP BAS control unit in the passenger fuse box and the Brake Switch. Diagnostic simply said the Brake Swich reading "ImPlausable". Hate that word. Cheers.

 

[Lozzar]

This is my next move (tomorrow March 7 2021). I especially like the test where you can connect the pump direct to a battery live and you should hear the pump engage.
Mercedes ABS pump Test, Diagnose, Removal Brake pressure Sensor

 

[Lozzar]

Anyone with the same Fusebox as mine (on a 2002 CL500) I've identified the ABS Pump Relay, See attached image. Bridge across Relay pins 30 + 87 (as per the video) simulating the working Relay, and you get direct voltage to the Pump and it makes a noise if the actual pump is ok. Mine made that noise. I am now testing the long connector plug for good voltage and good ground on the relevant ports (1 to 15). Pin 10 should be 5 volt, Pin 14 battery voltage. Again, watch the video above for an excellent demonstration. Next will be the smaller connector on the ABS pump, the Brake Switch connection. The Pins 30 + 87 are the pins which are 90 Degrees to each other. All ABS checks show the ABS unit is OK. Even pressing the Brake Pedal with ignition on raised the voltage on the ABS switch from 0.7 to 1.1 (without the Servo assisted). So I'm stuck now.

 

[mattkh]

Anyone with the same Fusebox as mine (on a 2002 CL500) I've identified the ABS Pump Relay, .

Well done.
A few thoughts I have.
When you say that on turning the ignition, the brake lights come on permanently, do you mean the 2 lamps at the boot .? What can be the reason for that..?
On another line of thought, is the level of the brake fluid in the reservoir OK.?
When you start the car, and press the brake pedal, does it feel softer than before..?

 

[Lozzar]

Another issue, which I suspect has no link to my main issue, is that the heater blower doesn't appear to be working. I didn't put it on during the last journey so I didn't notice it wasn't working. I'll look at it because I'm curious and who knows with this machine, it may in fact be connected?? I believe it's under the passenger glove compartment. I wonder what other surprises there might be??
I could try and check the single CAN Bus low for voltage I guess. Unfortunately I'm lost how to check the resistance. The obvious connection to check is CAN Low to battery positive and ground I guess, that might tell me something. Thanks for all your suggestions. I'll continue to check things and if I don't make any progress before the end of March I'll put it on Sorn. It has a nice number Plate, M500 GJA. The letters don't line up with my initials but it's still a nice plate though. I might put that on Retention as well because you can't do it once the MOT expires in September. Bit deflated now. back to the drawing board. I might visit my friendly Stratstone Mercedes people during the week and see what they say. Cheers.

 

[Lozzar]

Well done.
A few thoughts I have.
When you say that on turning the ignition, the brake lights come on permanently, do you mean the 2 lamps at the boot .? What can be the reason for that..?
On another line of thought, is the level of the brake fluid in the reservoir OK.?
When you start the car, and press the brake pedal, does it feel softer than before..?

Thank you Mattkh, yes the lights in the cluster at the back of the car. It's simulating the conditions when you press the brake pedal. That's why most peoples reaction is to blame the Brake Pedal Switch. The Brake light coming on without touching the pedal is a common symptom of the Brake Switch fault. The fluid level is ok, yes. The pedal feels ok I guess. Maybe there is a sensor on the brake reservoir that is giving false data? I could look into that.

 

[mattkh]

........ Carrying out the voltage check on this connection I had to set the multi-meter setting to 200m on the voltage scale (the scale goes from 600-200-20-2-200m) to detect the voltage on this connection. I reasoned that a switch only needs a small voltage to trigger something.
Kind regards.

Your mention above of a small voltage to trigger something got me thinking.
Please check your fuse box and any other documents you may have for a brake lights relay. I do not know if MBenz use one.

 

[Lozzar]

Your mention above of a small voltage to trigger something got me thinking.
Please check your fuse box and any other documents you may have for a brake lights relay. I do not know if MBenz use one.

There are a lot of Relays in there so yes, one may well be linked to the Brake switch and the ESP Module, thankyou, a great shout. I'll check every one. I did check all the black ones in the previous image which helped me to determine which relay linked to the ABS pump. Checking them all is not a difficult task. I will need to make sure I can use battery voltage on the pins that act as the "gate" to switch open the relay circuit. I don't think they're particularly expensive but I don't want to blow something else with an excessive voltage. There's usually a diagram printed on each relay. Cheers.

 

[mattkh]

Thanks.
We need a wiring diagram.
Relays are expensive, about £30-£50. But normally, they just need the flat pins to be cleaned.
Pin 30 is 12v from the battery, and you jump it to Pin 87, and as you say this is printed on the relay.

 

[Lozzar]

Thanks.
We need a wiring diagram.
Relays are expensive, about £30-£50. But normally, they just need the flat pins to be cleaned.
Pin 30 is 12v from the battery, and you jump it to Pin 87, and as you say this is printed on the relay.

I keep looking on the internet but it's not easy to find the exact diagram. They're all intellectual property to someone I guess. There are only 3 wires in the back of the Brake Pedal Switch (the two others are cruise control). I've already checked continuity (resistance) tracing it to the ESP BAS Module, housed in the same fuse box as the ABS relay. I need to check the voltage and the ground between the switch and the module on all three wires and then compare it to what it should be. Cheers.

 

[Doug1234]

2000 CL500 Brake Lights Stay ON All The TIme:

Interesting problem on this car. The vehicle came to us after visiting several other area MBZ private shops. The ABS Control Unit had been replaced, along with the rear S.A.M. and the brake light switch. Anytime the key was switched on, the brake lights came on and stayed on. I did not use a...

www.benzworld.org

Brake lights stuck on - MBWorld.org Forums

S-Class (W220) - Brake lights stuck on - I have a 2002 Mercedes s500 and when I turn my lights on or even if there off my brake lights don't turn off like I have my foot on the brake constantly so I was thinking maybe I need to change my brake light switch I do that and still lights do the same...

mbworld.org

Both the above threads mention either control unit faulty or fuses.

 

[Steve@Avantgarde]

So...

Having briefly scanned this thread, I would suggest you have missed, mainly because you probably arent able to, some basic diagnosis here.

Can you read the live data with your scanner? If so, you should be able to see the brake light switch function on/off. If that is the case, you could simply know that your switch, wiring and ABS controller are working perfectly without having to swap out sensors and modules.

Next can you read the ESM module with your scanner? If the answer is yes, can you look at live data? The live data on STAR has a value for brake light switch operation. Is the ESM seeing the brake light switch function? If the answer is yes, then comms from the ABS pump to ESM is ok. That confirms wiring, CAN and ABS module function and the fault is with your selector module.

The way I can be sure of all of that is because none of it would communicate without being able to talk to one another. Also, if you were using a half decent scanner, the CAN for the ABS runs off the chassis network, if you had a CAN issue, it would take out the whole network and report it as running in single wire mode affecting other modules along the way.

Throwing bits at it and swapping modules and pumps is a sure fire way to (a) costing you a shed load of time (b) money (c) a lot of frustration.

Diagnostic tools in the hands of the right people will save all of your messing around.