A 2007 Mercedes S600 had a CAN bus communication code on connector N47-5 to the ESP module. An ohms test on pins 18 and 19 reads 122 ohms and should be 60 ohms. What is the problem?
Thanks for your reply. A complete code scan revealed only a few other CAN bus issues; however, they were all related to and directly connected to this ESP module. The main code of concern was "No CAN Message Was Received From Control Unit N47-5(ESP Control Unit)." After looking at the wiring diagram and the Mercedes diagnosis information for this module, it says that those two pins should have a 60-ohm measurement. So I'm guessing that the next step should be tracing where those wires are coming from, which happens to be a connector under the passenger seat, so my next step was to go there and look at the wiring to see if there are any breaks or green crustys in the wires at that point. Does that sound right?
Thanks for your reply. A complete code scan revealed only a few other CAN bus issues; however, they were all related to and directly connected to this ESP module. The main code of concern was "No CAN Message Was Received From Control Unit N47-5(ESP Control Unit)." After looking at the wiring diagram and the Mercedes diagnosis information for this module, it says that those two pins should have a 60-ohm measurement. So I'm guessing that the next step should be tracing where those wires are coming from, which happens to be a connector under the passenger seat, so my next step was to go there and look at the wiring to see if there are any breaks or green crustys in the wires at that point. Does that sound right?
Yes, that sounds right.
Follow that bus around eith its distinctive colors (there are other non-similar buses).
List what are ALL the partners of ESP (is theABS-Brakes module) - There are less than 10 count but are all VIP Modules (ECU + TCU + SAM + ....)
Account them one by one...
one module is gonna be missing!
Concentrate on identifying that particular module.
Based on your scan report... now take a good guess to pin-point your "bad module".
Does your chassis have "BUS-BARS"
near front doors threshold or near footwells...
These areas routinely store rain water to help build green crusties.
Inspect for soaking evidences...
So you can see pin 1819 on the n47 connector shows it going to the x-30/28 connector. My star finder is not really a complete version of it and it doesn't have all the connectors as far as a picture of them and the pin out location of the connectors which is the case with the connector x-30/28. I'm new to reading wiring diagrams so if you could help me understand when looking at this picture of x-30/28, does it say that it is a seven-pin connector and somehow pin two is a double pin or something where the can low and high is coming in on the violet and the violet with white wire?
So you can see pin 1819 on the n47 connector shows it going to the x-30/28 connector. My star finder is not really a complete version of it and it doesn't have all the connectors as far as a picture of them and the pin out location of the connectors which is the case with the connector x-30/28. I'm new to reading wiring diagrams so if you could help me understand when looking at this picture of x-30/28, does it say that it is a seven-pin connector and somehow pin two is a double pin or something where the can low and high is coming in on the violet and the violet with white wire?
GREAT!
You have landed on the CAN-Bus BAR X30-28. It connects all the modules of this one bus.
Mercedes bus bar connector
Locate it physically and test each node.
Beware each slot is "private parking":.. don't scramble positions.
Keep each plug to its specific position.
Starfinder says this connector is located in the passenger-side front seat area. Do you know specifically where it's located and what has to be removed to reveal it?
Starfinder says this connector is located in the passenger-side front seat area. Do you know specifically where it's located and what has to be removed to reveal it?
This is 80% likely at the door threshold under long plastic cover piece.
(or 20% likely on the side of footwell, sometimes bus-bar there also)
Go with wire colors... many other twisted bus pairs found there as well.
REMEMBER bus connectors all look identical BUT EACH have their own unic location on the bus-bar.
RECOMMEND to Number them yourself before unplugging for testing...
If anyone has starfinder and you wouldn't mind looking up the w221 vehicle dynamics CAN connector location and screenshotting the pictures that it pulls up for the location on the passenger side floorboard I would appreciate it.
In the beginning, I discovered that on the N-47 connector, when unplugged, pins 18 and 19 had 120 ohms of resistance when they should have been 60 ohms. Next, I traced it back to connector X30/28. I located the x30/28 connector under the passenger seat (picture attached). X30/28 connector under the right front seat, passenger side
After locating this connector, I figured I would find some sort of green crusties, water intrusion, or cut in one of the wires but I didn't see anything obvious. Without referring to the diagnosis instructions, I immediately tested each pair of wires for resistance without unplugging anything. I got a reading of 60 ohms on each pair, and I was confused as to why I was getting 60 ohms when I was expecting to get some sort of out-of-range measurement on at least one pair of wires. At this point, I ran out of time and had to leave. I have since referred to this connector's diagnosis instructions (picture attached), which leads me to my next question. X30/28 pinout diagnosis.
1. How do these wires unplug? (CaliBenzDriver I appreciate the advice ("RECOMMEND to Number them yourself before unplugging for testing...")
2. Is this just like it sounds, and after unplugging each pair of wires to test, I should receive a reading of < 20 kOhm?
3. What would be the next step after receiving a reading outside this parameter?
For some reason, you are interested to test for Ohms...
Personally I don't have reason to test that besides knowing where R value stands (not so meaningful to test).
The termination resistor are built in the distribution bar... nodes are going to test equal...
(Where you're getting 120.Ohms is interesting to note what branch that is).
> What's more important is ...
what nodes are working ok
what nodes are faulty
what nodes are missing from network
Knowing that you can decide to focus on your bad guys.
I'm testing for ohms because that's what the Mercedes Xentry diagnosis says to test for. I had no communication with the ESP module, so I disconnected the connector and, per the diagnosis information, with the ignition off and the plug disconnected, N47-5 ESP connector
found pins 18 and 19 to have 120 ohms instead of the 60 ohms, as you can see in the picture attached.
I'm testing for ohms because that's what the Mercedes Xentry diagnosis says to test for. I had no communication with the ESP module, so I disconnected the connector and, per the diagnosis information, with the ignition off and the plug disconnected, N47-5 ESP connector
found pins 18 and 19 to have 120 ohms instead of the 60 ohms, as you can see in the picture attached.
So what does the Xentry test procedure conclude:
your ESP module is pass/fail?
Personally I don't think you can rule out a module as bad from measuring it at 120.Ohms
Check it ESP is getting power on +12V pins and chassis GND.
that is +12v and GND with ESP connector plugged in live, right?
So your test says ESP Module is not waking up to work over CAN?
After I did the scan tool and it said "No CAN Message Was Received From Control Unit N47-5(ESP Control Unit)." I went to the connector to the ESP and I actually unplugged it and tested pins one and two from battery ground and got 12 volts like the diagnosis said. I didn't see any way to get to the connector to back probe it with it plugged in because it had a huge shield on it and I didn't know if it was supposed to be tested when it was plugged in or disconnected because the diagnosis information did not say but at least the test worked and I got 12 volts on both pins. So I don't know.
After I did the scan tool and it said "No CAN Message Was Received From Control Unit N47-5(ESP Control Unit)." I went to the connector to the ESP and I actually unplugged it and tested pins one and two from battery ground and got 12 volts like the diagnosis said. I didn't see any way to get to the connector to back probe it with it plugged in because it had a huge shield on it and I didn't know if it was supposed to be tested when it was plugged in or disconnected because the diagnosis information did not say but at least the test worked and I got 12 volts on both pins.
So I don't know.
Well its close enough: 12V/GND disconnected is bettr than nothing. (we can assume that is okay without in-line drop).
Did you have ignition on or engine running to expect ESP fully powered/running. Dome modules (TCU) temain ghosted until fully powered up.
It does look like you're getting closer to calling a bad ESP module unlrss something is colapsing your CAN Bus !!!!
That's the whole point of working with the "bus distribution bar" one by one.
Obviously this creates tons of missing modules faults while disconnected!
You're only trying to clear the way for ESP to talk to these VIP's:
CGW + SAM + ECU : these modules call the shots to power up chassis (for troubleshooting).
Well its close enough: 12V/GND disconnected is bettr than nothing. (we can assume that is okay without in-line drop).
Did you have ignition on or engine running to expect ESP fully powered/running. Dome modules (TCU) temain ghosted until fully powered up.
It does look like you're getting closer to calling a bad ESP module unlrss something is colapsing your CAN Bus !!!!
That's the whole point of working with the "bus distribution bar" one by one.
Obviously this creates tons of missing modules faults while disconnected!
You're only trying to clear the way for ESP to talk to these VIP's:
CGW + SAM + ECU : these modules call the shots to power up chassis (for troubleshooting).
Yes, I had the ignition on while I was checking for power to pins 1 and 2. What is an in-line drop?
Yes, I had the ignition on while I was checking for power to pins 1 and 2. What is an in-line drop?
when you're dealing with poor connections, circuits measure fine without any load but as soon as you draw couple Amps the voltage drops down significantly.
Case in point the factory painted GND posts
or the salted GND strap
or the solderless pins
all look good until loaded the drop voltage shows up.
A poor connection is an in-line resistor
when you draw current through a resistor
you get an on-line dropped voltage.
Without load no voltage drop. The DVM uses nearly no current to measure voltage.
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