JC3388

Hi guys

I tried to hit the acceralator full to the kickdown switch but can't feel any extra power at all. I am sure it used to work prior to my service last month as well as changing the virbration adsorber.

Much appreciated if someone can guide me what and how to check whether it is a part fault or likely to be a ECU setting selection issue? I have experienced too many problems with this car and I am hoping it is a simple fix and won't cost me a fortune again.....

Many thanks
JC

AnimC32

I believe it's a dead button. Some people even remove it. If the car does not downshift when you floor it, something else might be wrong like IC pump failure (common problem).

edtv82

try doing a throttle reset... do a search on how its done... quick and easy usually rests the computer's history on your driving habits.

JC3388

Many thanks guys, appreciated for all your advices. I will have my car check up this Fiday by the mechanic who did the car service recently. I thought if I can give them some ideas what to look for, it will save their time as well as my wallet.

I always love Mercedes but never get much luck with them. A year ago, the gear box failed because coolant running to the gear box and spent thousandsssss to get it fixed.
Then last month, the virbration absorber is craked and costs me another thousand for the part again....If it isn't my dream car, I would have sell it long ago. I am going to get my number plate change (may be no lucky) after I find out what's wrong with the kickdown switch this Friday. I hope it is only some sort of computer setting (cheap and easy fix)

For the mean while, appreciate if anyone can give me any advice as I really don't know much technical stuff under the bonnet.

Million thanks!!
JC

gkstar

JC, I feel you need to tell us a bit more or troubleshoot a bit more. This can help in any case.

MB mechanic told me the button is not wired at all - it is only there to give feedback to the driver when you floor the pedal (one can feel the click).

It is likely one of two issues, both of which I (and many others) have experienced:

1. Throttle position sensor faulty: the car feels retarded AND does not downshift. You floor the pedal but ESU "sees it" being pushed about half way. When this happens, stop, turn engine off (no need to wait), start the car and problem disappears for a while. This fault logs a problem code that they can read at the garage. If this is the problem, you can swap sensors yourself.

2. IC pump toast. Note that in this case the trany will downshift as it should but car is sluggish. To make sure you have that problem: when it happens, slow down and drive at low rpm to give a chance for AIT to cool off a bit at which point the S/C will be back on and you will have power again. If it was the throttle sensor, the car would not recover until you restart the engine.

Good luck

alkrstev

Please keep us updated on this. I am having a similar problem to you where the car does not like to downshift. Thanks.

FrankW

the kick-down button is exactly what it sounds like. it force downshift the transmission to the lowest possible gear at any given speed. flooring the throttle without hitting the kick-down will not always make the transmission downshift to the lowest gear. however if you are in the lowest gear already flooring it to the kick-down switch will do nothing.

the only cars that the kick-down doesn't work is on the manual transmissions.

if your mechanic is telling it otherwise...run away from that shop and never go back.

JC3388

Thanks guys, I will try to explain more and hopefully I am saying the right things as I don't know any machanics.

Before the service and changing the virbration absorber, driving in "D" gear, if I floor the gas, the car will not repsonse for less than 0.5s and the then the power just pull me stick to the chair and it accelerate much faster than if I did not hit the kickdown switch. I hope that button is called the kickdown swtich as I was told before.

I will have my car check up tomorrow and hope it is an easy fix!! Will update you on this!!

Hi gkstar
What if the IC pump toast is not working? Is the part/s expensive and how long do you think it would take a mechanic as it will cost $90 Aus an hour. Many thanks

I finally changed my rego no as the one I got when I bought the car (2nd hand) gave me too much bad luck.

Cheers
JC

JC3388

Guys

I got my car back under 30 mins.

My mechanic checked whether there are any faults codes read and said there is none. He then reset the system and made sure he activated the kickdown switch. I can tell the difference when I drive. I can feel the car accelerate much better after 60km and as soon as I floor the gas and hit the kickdown switch, it is back, I can feel the power is back. From work to home, after the car service to yesterday, from work to home, the best was 12.7L/100 (office to home is under 20km) using freeway and today it only recorded 11.5L/100 which is quite consistent prior to the car service.

So I guess the kickdown switch is meant to do something to the car. It may not be for every Mercedes, but surely doing something for the C32.

It rain too heavy today so I did not have many chance to try the kickdown switch. I will re-confirm when I get a chance to try this when is a dry day

gkstar

Nice, glad to hear that.

The kick down switch function got me curios though. I have access to the service manuals for the C32 and will try to find out if it is wired or not on this model.

FrankW

once again. the kick-down switch make NO DIFFERENCE in power. it's simply used to downshift the transmission to the lowest gear possible at any given speed.

if you had a issue with throttle input not responding you most likely have a TPS issue.

JC3388

Hi FrankW, you are right, my car seems to get back to what it should be rather than gain any additional power. Before Friday, it didn't drive like an AMG at all.

Since you mentioned about TPS, I would like to know a bit more. What is TPS? Is it a common problem for the model? Is there anything to do or link with gear box. Also since so many people are complaining about the IC pump, should I be considering to have it change to the Johnson CM30? I only saw 1 on ebay for $200 GBP + 30 GBP shiping to Australia. Do you know is this a reaonsable price? Any modification is required to have this IC pump installed?

thanks mate

320 dreamer

the only mods needed for the cm30 pump is wrapping the body in some rubber tubing so it will fit snugly in the oem bracket. or you can drill a new hole and use the cm30 bracket. and lastly the cm30 has no plug on the end. simple fix is spade clips wrapped in tape but i prefer to remove the old plug from the old pump and solder it to the new wires on the cm30. then simply plug in. refill loss coolant and purge the system and enjoy!
there are those that use a bosch pump from a ford lightning but its still bosch and will likely fail within 40k miles. cheaper than the cm30 by about 50$. not worth it in my opinion

gkstar

TPS = throttle position sensor. See point #1 in my first reply.

anasdaouk

i pretty have a similar problem, im suspecting a tps...when i floor it down to max as in pressing the button it totally dies read carefully, dies as in it gets so sluggishhhhhh doesnt accelerate i can downshift manually it will re up but doesnt respond tgo my foot pressing...i put it on N rev it takes forever to rev till 5k...i turn it off start again no prob till i smash it with a kickdown so all the the problem occurs on kickdown...any clues???????????is tps expensive?btw IC pump new so no worries sure not from it as i can accelerate till 200km without anyproblem on condition i dont activate kickdown thnx all