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Car not starting - codes cleared - replaced fuel pump relay/CPS/TPS
Wife was driving down the road and car died on her.
Getting codes P0600 Serial Communication Link
P0161 o2 Sensor Heater Circuit
P0160 o2 Sensor Circuit No Activity Detected
P0123 Throttle/Pedal Position Sensor/Switch "A" Circuit High
SRS light on
ESP light on
Car will not start. Pulled top off gas tank to see if pump was turning on and pump not coming on.
Replaced fuel pump relay & Crank Position Sensor already...
Please help...
Start school in 3 wks for Auto Tech Specialist so this is a good trainer for me... Thanx in advance...
Last edited by Beatz; 12-20-2017 at 10:43 AM.
Reason: Deatil
Big number of errors popping at the same time indicate low voltage, or major communication failure.
Start with checking the car voltage. W211 allows displaying it on the cluster.
The codes were there before the car died. It was weird because sometimes when getting into the car the brake warning light would come on and prevent any power. You would have to turn off the car, remove the key, and open the door for it to reset. Sometimes it would take a few times before starting w/o the warning. It's the same warning that comes on when you hold the brake down too hard. It also happens during driving for no reason at all, or if someone cuts you off forcing you to hit the brakes harder then normal. It will go into down mode. No power and will have to go through the same routine as stated above. I was working on the steering wheel adjustment piece that broke and had some of the panels still off around the console.
I have only had the car for a few months and was trying to get everything fixed. The car was running okay, I thought so I fixed the steering wheel first so my wife could drive the car (6'2 vs 5'4). I'm a bit bigger. I checked the battery and it is low and will be put on charger this evening. However, I'm skeptical that's the main issue because the codes were already existing before the car died. When I researched them (not the o2 sensor ones) I found that the CPS could be bad so went ahead and replaced it. Was checking the fuel relay and it broke apart so I had to replace that. Asked a friend and he said to check the throttle position sensor. That was my next step but the part is $100+ on ebay so I wanted to ask the forum so see if they could tell me anything before spending the cash. Also, what does the MB scanner do that others dont? If a shop says that they can read my car how can I be sure they aren't ripping me off and won't be able to dig into the readings like the MB says they can? Will taking it to MB pin point the issue, or just cost me more money for information I already have?
Sorry, just trying to be detailed as best I can... Mercedes are a new animal for me...
When you have low car voltage, at one point or the other all sensors will malfunction, so don't replace the sensors when you know you have charging problem.
Once the codes come on, they will take some time to clear even when the voltage comes back to normal.
So one step at the time. Get the battery charged, clear the codes, start the car and OBSERVE THE VOLTAGE.
How old are alternator brushes?
SD scanner will do adaptations and coding, but even my $12 Bluetooth scanner with Torque will clear MB engine codes.
When you have low car voltage, at one point or the other all sensors will malfunction, so don't replace the sensors when you know you have charging problem.
Once the codes come on, they will take some time to clear even when the voltage comes back to normal.
So one step at the time. Get the battery charged, clear the codes, start the car and OBSERVE THE VOLTAGE.
How old are alternator brushes?
SD scanner will do adaptations and coding, but even my $12 Bluetooth scanner with Torque will clear MB engine codes.
That was my next question... which app works best with Android... I was using OBD Car doctor and just downloaded Torque to compare which is better so I can get the pro version.
I will charge her up and clear the codes and then check voltage and get back with you. I really do appreciate the help.
When you have low car voltage, at one point or the other all sensors will malfunction, so don't replace the sensors when you know you have charging problem.
Once the codes come on, they will take some time to clear even when the voltage comes back to normal.
So one step at the time. Get the battery charged, clear the codes, start the car and OBSERVE THE VOLTAGE.
How old are alternator brushes?
SD scanner will do adaptations and coding, but even my $12 Bluetooth scanner with Torque will clear MB engine codes.
I should know, but I don't. Yours is a 2003? Does it have the second battery under the hood?
Yes, all cars with SBC had the aux battery so also check the aux battery in addition to the main on. I think the older 2003 also had a battery control module also. If you're thinking of taking it to an MB dealer to have the codes read, you mind as well just buy an MB specific code scanner. There are many of them and they start at the $50 range, but you might want to spend a little more and get one that can also bleed the SBC for you. It's going to cost the same as taking it to the dealer to get the codes read and you'll have a code scanner that can read MB codes afterwards. Not sure about a couple of the other codes, but if they're still there after clearing them, the O2 problem sounds like a wiring issue. Check to make sure the wiring isn't damaged. You might also want to search the old threads, no one has mentioned the throttle problem position sensor problem in a while but I believe that's also a common part have also been replaced in the past.
P0123 indicates that, key on, the ECM is reading >4 volts from the throttle/pedal position sensor when the voltage should be around 0.2 volts. So, the ECM is seeing the throttle at wide-open.
You can troubleshoot the throttle position sensor and the pedal position sensor using a multi-meter. I'd lean towards the TPS being bad as a bad PPS should throw a P0120.
Historically the TPS and PPS are always mixed in descriptions, so double check what is it. I figure out that software programmers can't tell the difference between throttle and pedal, that is why we have such common mistakes.
I had PPS failure on diesels (they don't have throttle, so that was easy troubleshooting as code was showing TPS) and it did not kill the engine, just chocked it at some points and put it in default mode (limited performance).
Watching the video, I have to point that you should not work on car in closed garage with water heater standing. Years ago people died in California when they work on gasoline tank and fumes ignited from WH pilot light.
Located the TPS. Does anyone have a diagram of which wires to test? Where is the PPS?
I found a iCarsoft I980 scanner on Amazon for $113 I wanted to see if anyone had any feedback on. According to the article on mercedesmedic it can read & clear DTC/SRS/ABS/Transmission codes on MB and others. Good investment?
Last edited by Beatz; 12-17-2017 at 03:31 PM.
Reason: Added details
The pedal position sensor is a part of the accelerator pedal. If you post your VIN I'll see if I can pull the schematics on your car and let you know which wire is which on the throttle position sensor. Might take me a little while as the schematics are not the easiest to read due to the way they are organized and formatted.
I also have the iCarSoft i980 as part of my troubleshooting tools. It's pretty good and much faster to set up than the full up DAS.
I keep reading scanner topics as I don't want to sink $700 into C4 and deal with software hacking, so lately good recommendations come for $149iCarSoft Mercedes/Smart MB II
I also own MaxiEcu, what is good value IMHO and will do MB adaptations, but it is European models-oriented and does not cover all modules found in US models.
Disregard VIN request; looked it up by model designation.
TPS module appears to have two circuits inside.
Pin 1 -common to both sides. Unknown if ground or power.
Pins 6 and 3, one per side, Unknown if ground or power.
Pins 5 and 4, one per side, possibly the signal out indicating throttle position?
1,5,6 comprise one side. 1,4,3 comprise the other side.
PPS appears to be a plain potentiometer but I could be wrong.
Recommend a more advanced diagnostic system to narrow the fault down to the TPS or PPS. It's most likely going to one or the other or a poor connection at the sensor(s).
*will update after wire testing...
Tested wires. Only got reading off #1 blue w/ white line (4.9). Also I dont hear the fuel pump turn on at all. Is that because of the po123 error?
Anyone know what size these screws are?
T9?
Last edited by Beatz; 12-17-2017 at 05:01 PM.
Reason: Update
It was weird because sometimes when getting into the car the brake warning light would come on and prevent any power. You would have to turn off the car, remove the key, and open the door for it to reset.
Something to consider pedal (part # 2113000804) incorporates accelerator & position sensors of which MB does not offer separately that communicate with sensor on BOU.
Last edited by konigstiger; 12-18-2017 at 10:35 AM.
Something to consider pedal (part # 21130008040) incorporates accelerator & position sensors of which MB does not offer separately that communicate with sensor on BOU.
I’m suggesting how to address MB DTC P20DD / generic P0123 B37 (accelerator pedal sensor) signal. Part # typo corrected in previous post.
Yes. Thank you for doing so. I just wanted to know if having a bad sensor (pedal - Po123) would prevent the fuel pump from turning on. Also, how do you check those sensors in the diagram you posted (PBC & PVS).
I just didn't know if MB had a code for bad fuel pump or if its just something that goes and you have to diagnose (relay,ignition, fuel pump, fuel filter, etc) by process of elimination. Like I said, new to MB...
Thanx in advance...
Last edited by Beatz; 12-18-2017 at 11:16 AM.
Reason: stress
Would a bad sensor prevent the fuel pump from turning on also? I don't hear it coming on.
Remember, when you turn the key to the "on" position the fuel pump only activates for one second to pressurize the fuel rail and then turns off until the ECM senses crankshaft revolutions or air flow. Best way to verify is to attach a fuel pressure gauge to the fuel rail and confirm pressure.
Also, I doubt this is it, but this fellow had a bad relay that was killing his car. With your multiple error codes, I doubt it is the relay but it is an easy check. https://mbworld.org/forums/e-class-w...rt-number.html
Remember, when you turn the key to the "on" position the fuel pump only activates for one second to pressurize the fuel rail and then turns off until the ECM senses crankshaft revolutions or air flow. Best way to verify is to attach a fuel pressure gauge to the fuel rail and confirm pressure.
Also, I doubt this is it, but this fellow had a bad relay that was killing his car. With your multiple error codes, I doubt it is the relay but it is an easy check. https://mbworld.org/forums/e-class-w...rt-number.html
As always, Konigstiger provides great info.
Yes I have gotten very valuable information from all contributors. Thanks to all of you. I don't think its the relay either since mine fell apart when I pulled the cover off the fuses. It got stuck and I guess it caught the side and ripped the plastic off. I was removing it with a screwdriver and accidentally broke it and replaced it already.
The reason I asked about the pump is because when I first had the issue and researched it, I thought it could be the pump so I pulled the back seat out to test the pump (check hoses) but got no readings. Same at relay in trunk & sending unit behind the driver. I also didn't see any return on the lines with the key on. I haven't checked it since I cleared the codes though.
12-15-2017, 11:43 AM
Car not starting - codes cleared - replaced fuel pump relay/CPS/TPS
I tend to get a head of myself stressing out...
