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Discussion Starter #1
Hello to all,

Unfortunately the wiring insulation on the throttle actuator of my C280 went bad. I replaced the wiring and there seems that there are no short circuits between pins.

The car seems to still show some of the symptoms of the bad wiring (fluctuating idle, some smoke sometimes), so now I need to check if my throttle actuator is in good condition, so I am looking for the pin designation on the throttle actuator's plug, or the internal diagram (or schematic) to make electrical tests to see if the throttle position sensor, or something else inside the throttle actuator, is bad.

If someone here can help me with this, I would really really appreciate your help!!

Regards,

Bob
 

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Is this what your looking for?

 

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Discussion Starter #4
Hello guys,

Thank you so much for the links for the wiring diagrams, they sure will be helpful at some moment. The pin designation I am looking for is like a "pin1 - GND, pin2 - Throttle position +..." type diagram.
These diagrams may help to find out the pins in some way, but I noticed that the diagrams show that the throttle actuator has 11 connection pins, but the one in my car has 8 connection pins so it is a bit difficult to compare it to the diagrams.

Thanks!

Bob
 

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Discussion Starter #6
Hello to all,

Thinking that I had nothing to loose, I emailed VDO support about this. I thought that, being a 16 year-old part, they were not going to help me. But actually they replied back to me with the pin diagrams!! So I will post them later so they are available if anyone else needs them. Having this diagram, plus the car electric diagrams (posted before on this thread) will help to troubleshoot the throttle actuator to see if something besides the wiring is bad.

I will post the information VDO provided me soon!

Regards,

Bob
 

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Discussion Starter #8
Hello to all,

Finally I am here with the information from VDO:

"Pin Description
1 IPDK Actual value potentiometer throttle valve
2 IPA Actual value potentiometer actuator
3 POT+ Potentiometer plus
4 MOT+ Motor plus
5 ULLK Idle switch contact
6 LLK Idle switch contact
7 POT- Potentiometer minus
8 MOT- Motor minus

The idle contact switch is used to detect if the driver has removed the foot from the accelerator pedal. In such case the idle switch should be closed. In case the driver opens the plate manually, the switch will be opened. During operation of the integrated drive (during idle speed control) the switch will be kept closed.
Some applications perform an additional plausibility check between the IPDK potentiometer output and the IPA potentiometer output. Both have to be in a defined relation as long as the idle switch is closed. So, if these values deviate more than the allowed tolerance, the system might not trust the idle switch signal anymore and switch into limp home mode.”

The people at VDO did not tell me this “allowed tolerance” value from where the system does not “trust” the idle switch.

After receiving this information, I proceeded to perform some measurements at the terminal connector of the throttle actuator (which I suspect may be faulty) using a digital multimeter, and this is what I got:

My measurements are (“Pins” mean where the measurement instrument’s terminals were connected, and the “closed, half open, and open” means the position of the throttle flap at the moment of the measurement):

• Idle Switch (Pins 5 and 6, Closed): 724Ω
• Motor (Pins 4 and 8): 17.8Ω
• Pot (Pins 3 and 7): 1.023kΩ

• Actual value pot throttle valve:

Pins 1 and 7: Closed 2,90kΩ, Half open 4,48kΩ, Open 2,15kΩ

Pins 1 and 3: Closed 2,1kΩ, Half open 4,48kΩ, Open 2,90kΩ


• Actual value pot actuator:

Pins 2 and 7: Closed 1,517kΩ, Half open 1,517kΩ, Open 1,517kΩ

Pins 2 and 3: Closed 1,034kΩ, Half open 1,034kΩ, Open 1,034kΩ



Now, if someone here could also perform these same measures at his/her car, this could help me and other members to know if we have a bad throttle actuator. And also would provide the measurement data to check different throttle actuators for faults for future members on this forum!!

Thanks to all, and please test your throttle actuators and post your results!!

Bob
 

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Discussion Starter #9
Hello,

I forgot to include in my previous post, that if someone wants to know how to access the connection socket of the Throttle actuator in an easy way, to perform the measurements, I can post some pictures about how to do it ;)

Regards,

Bob
 

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Discussion Starter #10
Hello,

Can anybody help? The guy at VDO stopped responding the emails, so now I am on my own again, and my car is still parked collecting dust!! (I can't wash it where it is parked right now :()
 

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Hi, check out this link, I recently re-wired mine. Unfortunately, I still get the fluctuating idle, so I don't know what is actually going on, perhaps the position sensor in the unit is bad, or maybe another wiring problem somewhere else.

http://www.benzworld.org/forums/w202-c-class/1276169-repairing-your-engine-wiring-harness-17.html
Harlz, were you able to isolate the cause of the fluctuating idle? My coolant temperature sensor was faulty and caused a similar issue when the engine is still cold. Replaced it and problem gone!:)
 

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Hello to all,

Finally I am here with the information from VDO:

"Pin Description
1 IPDK Actual value potentiometer throttle valve
2 IPA Actual value potentiometer actuator
3 POT+ Potentiometer plus
4 MOT+ Motor plus
5 ULLK Idle switch contact
6 LLK Idle switch contact
7 POT- Potentiometer minus
8 MOT- Motor minus

The idle contact switch is used to detect if the driver has removed the foot from the accelerator pedal. In such case the idle switch should be closed. In case the driver opens the plate manually, the switch will be opened. During operation of the integrated drive (during idle speed control) the switch will be kept closed.
Some applications perform an additional plausibility check between the IPDK potentiometer output and the IPA potentiometer output. Both have to be in a defined relation as long as the idle switch is closed. So, if these values deviate more than the allowed tolerance, the system might not trust the idle switch signal anymore and switch into limp home mode.”

The people at VDO did not tell me this “allowed tolerance” value from where the system does not “trust” the idle switch.

After receiving this information, I proceeded to perform some measurements at the terminal connector of the throttle actuator (which I suspect may be faulty) using a digital multimeter, and this is what I got:

My measurements are (“Pins” mean where the measurement instrument’s terminals were connected, and the “closed, half open, and open” means the position of the throttle flap at the moment of the measurement):

• Idle Switch (Pins 5 and 6, Closed): 724Ω
• Motor (Pins 4 and 8): 17.8Ω
• Pot (Pins 3 and 7): 1.023kΩ

• Actual value pot throttle valve:

Pins 1 and 7: Closed 2,90kΩ, Half open 4,48kΩ, Open 2,15kΩ

Pins 1 and 3: Closed 2,1kΩ, Half open 4,48kΩ, Open 2,90kΩ


• Actual value pot actuator:

Pins 2 and 7: Closed 1,517kΩ, Half open 1,517kΩ, Open 1,517kΩ

Pins 2 and 3: Closed 1,034kΩ, Half open 1,034kΩ, Open 1,034kΩ



Now, if someone here could also perform these same measures at his/her car, this could help me and other members to know if we have a bad throttle actuator. And also would provide the measurement data to check different throttle actuators for faults for future members on this forum!!

Thanks to all, and please test your throttle actuators and post your results!!

Bob
Sorry if I misunderstand you. Do you still want us to perform these measures for your comparison? What I recall off the top of my head is that mine were not very far from yours. Actually I had just re-wired my spare (old and previously faulty :D) actuator - thanks Harlz http://www.benzworld.org/forums/167849-harlz.html - and I used the values obtained from the known good and working one to set the repaired one. I will redo the measurements and post back, if it will help.
By the way my re-wired actuator is the one still running the car. No codes, no problems and yet I had replaced it due to driveability issues.:thumbsup:
 

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So I performed measurements on my throttle body of a C180.
Part number 000 141 9 25

Pin 5-6 IDLE Switch 718Ω

Pin 4-8 MOTOR 3.5Ω

Pin 3-7 POT 1.352KΩ

Actual value pot throttle valve:

Pin 1-7: Closed 3.5KΩ/Half open 3.45KΩ/Open 2.9KΩ
Pin 1-3: Closed 2.890KΩ/Half open 5.40KΩ/Open 4.53KΩ

Actual value pot actuator:

Pin 2-7: Closed 4.93KΩ/Half open 9.92KΩ/Open 11.31KΩ
Pin 2-3: Closed 4.21KΩ/Half open 13.00KΩ/Open 12.86KΩ

So, my measurements ARE WAY OFF, from yours bob, and I do seriously suspect I have a throttle body issue, after a throttle reset, the car did performed a little bit better, but as the measurements are not linear, I'm pretty sure the PMS/ECU is getting confused, like "dude, what the hell are you doing, throttle open or close?"

I'm going to see if I can get a second hand unit cheap...
Can't VDO give us the values?
Mine are quite oscillating all the time, not much fixed values...Those values are average values...
 

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Discussion Starter #14
Hello,

Mugavana and impulse-sond.com, thank you for your responses. Mugavana, yes I still need the measurements to compare with mine. I suppose it is bad because I rewired it, checked that it has no shorts on it, but after re-installing it on the car, it still has a fluctuating idle, and it stalls very easy. I also see the values for pins 2-3 suspicious, since they don't change while opening the actuator. So I thought the only way to be sure is bay measuring a "good" unit. I also haven't done nothing else to the car, like resetting the ECU or something. If someone can tell me how to do this I would really appreciate it.


Thanks,

Bob
 

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Discussion Starter #15 (Edited)
Hello again,

Impulse - sound.com, sorry, could you please tell me what a "throttle reset" is? May be it is the missing step in fixing my car!

By the way, my actuator it PN 000 141 65 25

Thanks,

Bob
 

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Do you own a security torx bit set?


I will walk you thru the proper diagnosis.

Let me see if I can go find the diagram I posted, I moved stuff in my photobucket, so stuff is messed up.
 

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1995 W124 M111 E200

Harlz, were you able to isolate the cause of the fluctuating idle? My coolant temperature sensor was faulty and caused a similar issue when the engine is still cold. Replaced it and problem gone!:)
Mugavana,

Finally I get my nearest helper! My car has a problem that I believe can be solved. I replaced the actuator but could not connect back the eight wires back to those from the PMS. I rewired the loom from the PMS to the engine and therefore the wire colours differ considerably from those from the actuator. After reconnecting, the car starts very well but goes off or struggles to idle immediately I press my foot on the accelarator so I believe the connection between the actuator and PMS is inncorrect (at least in so far as the eight wires are concerned). Worse still I cannot load, it only idles, at load it cannot even move an inch. I am in Kakamega and my number is 0733 20 19 95. Please help me. I have no clue completely on all this things about measuring the TPS, potentiometer and the rest, ni saidie Sir. I can be able to access the wire numbers from the PMS and their respective functions but joining them to the actuator wires is the issue - I do not have a connector socket for that matter - which won't help in any case. I request for a full description of the 13 wires from the PMS and to what colour should they connect to the actuator wires (the actuator wires have the OEM colours)
 

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Mugavana,

Finally I get my nearest helper! My car has a problem that I believe can be solved. I replaced the actuator but could not connect back the eight wires back to those from the PMS. I rewired the loom from the PMS to the engine and therefore the wire colours differ considerably from those from the actuator. After reconnecting, the car starts very well but goes off or struggles to idle immediately I press my foot on the accelarator so I believe the connection between the actuator and PMS is inncorrect (at least in so far as the eight wires are concerned). Worse still I cannot load, it only idles, at load it cannot even move an inch. I am in Kakamega and my number is 0733 20 19 95. Please help me. I have no clue completely on all this things about measuring the TPS, potentiometer and the rest, ni saidie Sir. I can be able to access the wire numbers from the PMS and their respective functions but joining them to the actuator wires is the issue - I do not have a connector socket for that matter - which won't help in any case. I request for a full description of the 13 wires from the PMS and to what colour should they connect to the actuator wires (the actuator wires have the OEM colours)
Hi Otsola,
The problem you describe could be caused by many different factors. In order to get the most helpful pointers here I would suggest you go a little further back and tell us why you felt you had to replace the actuator, and re-wire the harness (what were the symptoms / problems at that time?).
Based on the little you've described here my first suspect would be the Mass Airflow Meter, which you can easily check by disconnecting it to see if there's any change in throttle response and ability to maintain a fairly stable RPM. I hope (for your sake) that this is not the culprit because it costs some $$$!:mad:
Important as it is, the throttle actuator on its own shouldn't prevent the engine from idling fairly smoothly, or the RPMs from responding to the accelerator pedal position ( though of course it affects your gas mileage and emission levels, power etc.)
I'd therefore recommend that you first focus your energies on sorting out the idling and lack of throttle response issues before trying to address the actuator wiring bit.
One other thing - if the engine could start and maintain a fairly stable RPM, and could respond to the accelerator pedal prior to the re-wiring you carried out, you may want to re-check the work you did :D because mistakes do happen...
I hope this helps, but post back with any progress made and you can be sure that there'll be many members here willing to assist.
 
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