bp71k5
3/4 ton status
Anyone have experience with them? I have an SLK230 that has a problem with either the throttle position sensor or the pedal position sensor and I can’t figure out if those are the same thing or not. It’s a drive by wire model.
CK5
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Mercedes info
- Thread starter bp71k5
- Start date
Small amount of experience. I've owned three of them. Not that model.
The two parts you mention are related, but not the same. The throttle position sensor tells the computer the position of the throttle plate from closed to wide open. The computer commands the throttle motor to move the throttle and the position sensor tells it where it is and when its in the right position.
The pedal position sensor takes the place of the throttle cable. Its a device, usually a potentiometer, which tells the computer how far you press the accelerator pedal. The computer then commands the throttle motor to move that amount.
Interestingly, on my '98 M-Class, there was still an accelerator cable. But, it went from the pedal out to a pedal position sensor mounted on the firewall under the hood, and was not connected to the throttle at all.
I suspect that it was easier to keep the old style pedal system and just use a shortened cable to turn the sensor. To go to a dedicated pedal position sensor like the cars use today, you would have to redesign the pedal hinge system and mount the sensor on to it under the dash.
The two parts you mention are related, but not the same. The throttle position sensor tells the computer the position of the throttle plate from closed to wide open. The computer commands the throttle motor to move the throttle and the position sensor tells it where it is and when its in the right position.
The pedal position sensor takes the place of the throttle cable. Its a device, usually a potentiometer, which tells the computer how far you press the accelerator pedal. The computer then commands the throttle motor to move that amount.
Interestingly, on my '98 M-Class, there was still an accelerator cable. But, it went from the pedal out to a pedal position sensor mounted on the firewall under the hood, and was not connected to the throttle at all.
I suspect that it was easier to keep the old style pedal system and just use a shortened cable to turn the sensor. To go to a dedicated pedal position sensor like the cars use today, you would have to redesign the pedal hinge system and mount the sensor on to it under the dash.
bp71k5
3/4 ton status
Looking into it more, it’s sounding like the pedal in the 01 and newer models may hold both sensors in it. Online parts places only list a new pedal assembly in a search for those sensors. Maybe I can have a dealer look it up for sure. I’ll have to pull the engine cover and dig deeper. I’ve seen pictures for the earlier models showing the TPS on the brake booster, but this one has nothing like it in that area.
Nope, they are two different units. My car has the one mounted either on the brake booster or right next to it. I don't feel like walking out and looking, since it won't help with yours.
RockAuto shows both for a 2001 SLK230.
The throttle position sensor is under "fuel & air", right where you would expect it to be.
But, the pedal position sensor is under "interior", which, I guess kinda makes sense.
Unfortunately, you are SOL if you need one. They both show out of stock.
But they do have pictures, so you can identify them.
Just a guess going by the number of pins, I suspect they are both dual pots that work in opposite directions. I have seen that before. The computer expects the outputs to go at the same rate in opposite directions. If they don't match, it knows there is something wrong, and throws a code.
And for that matter, I have seen them go in the same direction on some cars. It compares the output of each to make sure its a valid reading.
If you don't see them on RockAuto, let me know, and I'll post the part numbers. But they are fairly easy to find when you know where to look.
J.
RockAuto shows both for a 2001 SLK230.
The throttle position sensor is under "fuel & air", right where you would expect it to be.
But, the pedal position sensor is under "interior", which, I guess kinda makes sense.
Unfortunately, you are SOL if you need one. They both show out of stock.
But they do have pictures, so you can identify them.
Just a guess going by the number of pins, I suspect they are both dual pots that work in opposite directions. I have seen that before. The computer expects the outputs to go at the same rate in opposite directions. If they don't match, it knows there is something wrong, and throws a code.
And for that matter, I have seen them go in the same direction on some cars. It compares the output of each to make sure its a valid reading.
If you don't see them on RockAuto, let me know, and I'll post the part numbers. But they are fairly easy to find when you know where to look.
J.
bp71k5
3/4 ton status
That’s weird cause I got nothing even remotely close to looking like that anywhere near the brake booster
Oops, we got off on the wrong track.
I'll snap a pic of the unit on my car tomorrow, but that is not what you should be looking for. Mine is the 1998 model, and has got to be one of the earliest examples of drive-by-wire that the company used. Basically they just shortened the original throttle cable and hooked it to the unit next to the brake booster.
Then they hooked a stepper motor to the throttle where the cable used to hook up, and let the computer move the throttle according to the movement of the throttle pedal sensor.
Yours is the later design which is designed to be drive-by-wire to start with. So the cable and unit by the brake booster is gone.
Look at the pedal position module picture on RockAuto. That bumpy surfaced plate is pressed down either by your foot directly, or the back side of the pedal.
As its pushed down, the lever moves the potentiometer(s) which tells the computer how far to move the throttle.
Look under the pedal, inside the car, and I think you will find it. If not, push the pedal down and see what moves. That unit is going to be right there somewhere.
The TPS is going to mounted on the side of the throttle body somewhere and the little arm will turn as the throttle plate moves.
Just an educated guess, but I imagine both of those units can be tested with an ohmmeter. With two rows of three pins, most likely the two outside pins are both ends of the pot, and the center is the wiper.
Does not have to be that way, of course, but its the most common way of arraigning things.
Just in case there are some active components inside, I would not use the diode setting of the meter to keep the test voltage low.
J.
I'll snap a pic of the unit on my car tomorrow, but that is not what you should be looking for. Mine is the 1998 model, and has got to be one of the earliest examples of drive-by-wire that the company used. Basically they just shortened the original throttle cable and hooked it to the unit next to the brake booster.
Then they hooked a stepper motor to the throttle where the cable used to hook up, and let the computer move the throttle according to the movement of the throttle pedal sensor.
Yours is the later design which is designed to be drive-by-wire to start with. So the cable and unit by the brake booster is gone.
Look at the pedal position module picture on RockAuto. That bumpy surfaced plate is pressed down either by your foot directly, or the back side of the pedal.
As its pushed down, the lever moves the potentiometer(s) which tells the computer how far to move the throttle.
Look under the pedal, inside the car, and I think you will find it. If not, push the pedal down and see what moves. That unit is going to be right there somewhere.
The TPS is going to mounted on the side of the throttle body somewhere and the little arm will turn as the throttle plate moves.
Just an educated guess, but I imagine both of those units can be tested with an ohmmeter. With two rows of three pins, most likely the two outside pins are both ends of the pot, and the center is the wiper.
Does not have to be that way, of course, but its the most common way of arraigning things.
Just in case there are some active components inside, I would not use the diode setting of the meter to keep the test voltage low.
J.
OK, since I am inherently lazy, instead of taking a picture tomorrow, I went searching on the web.
Found this picture. The sensor is the unit under the swing arm with the cable attached. The cable goes through the firewall, and is hooked to the pedal.
The white cap to the right is the brake fluid cap.
Like I say, you do not have one of these. This is what is on my older car.
Found this picture. The sensor is the unit under the swing arm with the cable attached. The cable goes through the firewall, and is hooked to the pedal.
The white cap to the right is the brake fluid cap.
Like I say, you do not have one of these. This is what is on my older car.
bp71k5
3/4 ton status
Ok starting to make sense. I have a new pedal on order and I’ll take the engine cover off and see if I can find the throttle body and TPS in there. The problem is super intermittent, but sounds common for these models.
bp71k5
3/4 ton status
Here’s a picture with the engine covers off. Still not seeing anything, except this one connector on the throttle body with 6 wires that looks like a round servo shaped thing next to it. Look familiar on yours?
Good news is, you found it.
Bad news is, you found it.........
That is the throttle servo, which moves the throttle under the control of the computer. In this case, it looks like the TPS is built in, so more than likely you will have to replace the whole thing.
They are not cheap, but by shopping around you should be able to beat the $1200 price tag I saw on a Mercedes parts page. The 230 parts are cheaper than the 320 parts in 2001 models. I see them from that price down to $120. Don't recommend either of those extremes.
Here is one link I found.
www.carid.com
Click on the Bosch one. It says the TPS is built in. Warning, I do NOT know if that is the right one for your car.
Before I started thinking about replacing that unit, I would try carefully unplugging that connector to make sure there is not a problem in there.
Some of those connectors are push tabs, some lift tabs, and some have a plastic lock tab you have to slide out first.
Can't tell from the pic which that is.
That front plastic cover looks like it is removable by removing the little metal clips. I would not do that except as a case of last resort. Not sure that even if you get the cover off, you would find anything in there that could be replaced or repaired.
And it may not want to go back together.
What are the symptoms you are having? Intermittent throttle response? I would suspect that if either the TPS or the APS is flaky, it ought to set a code that you can read with a good scanner.
Some of the newer cars even have a learn procedure that teaches the computer what the values of both sensors are if they have drifted due to age.
Most of those require a good scan tool that can talk to the CanBus.
J.
Bad news is, you found it.........
That is the throttle servo, which moves the throttle under the control of the computer. In this case, it looks like the TPS is built in, so more than likely you will have to replace the whole thing.
They are not cheap, but by shopping around you should be able to beat the $1200 price tag I saw on a Mercedes parts page. The 230 parts are cheaper than the 320 parts in 2001 models. I see them from that price down to $120. Don't recommend either of those extremes.
Here is one link I found.
Throttle Body Replacement — CARiD.com
With quality parts and tools that come from top names in the game, we’ve got all of your throttle body replacement needs covered.
Before I started thinking about replacing that unit, I would try carefully unplugging that connector to make sure there is not a problem in there.
Some of those connectors are push tabs, some lift tabs, and some have a plastic lock tab you have to slide out first.
Can't tell from the pic which that is.
That front plastic cover looks like it is removable by removing the little metal clips. I would not do that except as a case of last resort. Not sure that even if you get the cover off, you would find anything in there that could be replaced or repaired.
And it may not want to go back together.
What are the symptoms you are having? Intermittent throttle response? I would suspect that if either the TPS or the APS is flaky, it ought to set a code that you can read with a good scanner.
Some of the newer cars even have a learn procedure that teaches the computer what the values of both sensors are if they have drifted due to age.
Most of those require a good scan tool that can talk to the CanBus.
J.
bp71k5
3/4 ton status
I had a feeling that servo inside the throttle body is what I was aimed at. Symptom is I press the gas pedal and nothing happens for about 2 seconds, then it realizes someone’s on the pedal and lurches into action. I’ve read the pedal sensor also tends to go bad so I took a chance and threw the cheaper/easier part at it by replacing the gas pedal.Good news is, you found it.
Bad news is, you found it.........
That is the throttle servo, which moves the throttle under the control of the computer. In this case, it looks like the TPS is built in, so more than likely you will have to replace the whole thing.
They are not cheap, but by shopping around you should be able to beat the $1200 price tag I saw on a Mercedes parts page. The 230 parts are cheaper than the 320 parts in 2001 models. I see them from that price down to $120. Don't recommend either of those extremes.
Here is one link I found.
Click on the Bosch one. It says the TPS is built in. Warning, I do NOT know if that is the right one for your car.Throttle Body Replacement — CARiD.com
With quality parts and tools that come from top names in the game, we’ve got all of your throttle body replacement needs covered.
Before I started thinking about replacing that unit, I would try carefully unplugging that connector to make sure there is not a problem in there.
Some of those connectors are push tabs, some lift tabs, and some have a plastic lock tab you have to slide out first.
Can't tell from the pic which that is.
That front plastic cover looks like it is removable by removing the little metal clips. I would not do that except as a case of last resort. Not sure that even if you get the cover off, you would find anything in there that could be replaced or repaired.
And it may not want to go back together.
What are the symptoms you are having? Intermittent throttle response? I would suspect that if either the TPS or the APS is flaky, it ought to set a code that you can read with a good scanner.
Some of the newer cars even have a learn procedure that teaches the computer what the values of both sensors are if they have drifted due to age.
Most of those require a good scan tool that can talk to the CanBus.
J.
So far so good, but my problem was intermittent and so I’ll have to keep an eye on it over the next week to see if it returns. The throttle response is really different now so I know something changed.
