throttle pedal doesnt do anything

having rebuilt my head, camshaft and timing belt, the throttle pedal does nothing in drive or reverse, it works in park and neutral.

What does the Vag-Com say? Does the car think the brake is depressed (via the switch)?

If the car thinks the brake pedal is pressed, it kills the throttle pedal.

mr.abacus, i do not own this car it belongs to a friend, i have only the very basic scanner, i do not live where access to a vagcom scanner is and i doubt if there is one within a 100 miles of my location.

having said that, i am a very good mechanic, must i have the equipment to repair the car, has this fault ever appeared before, if the former is true then it will have to be towed some 150 miles to the nearest vw dealer.

if as you say the switch may be at fault, i have done some checks on that very item,

terminals 1-4 are open and terminals 2-3 are closed without the pedal being depressed,

this is the reverse when the pedal is pressed,

acording to alldata teminals 2-3 are connected to the ECM, if i am looking at the correct diagram, there is a choice of 4

there is one code stored P0183 fuel temperature sensor.

the glow plug light is not blinking

note that since my first post which required me to log on 9 times before i could navigate the site, i have had a power outage, my modem whent down and it takes approimately 2 minures to open your page.

as it would seem that someone knows something about this car here i will persiveer.

no its just under the 1000 rpm mark

apart from the code P0183 and no throttle operation in gear there are no other symptoms

john hennessy said:

having rebuilt my head, camshaft and timing belt, the throttle pedal does nothing in drive or reverse, it works in park and neutral.

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A proper scan tool for this car should have been in your arsenal of tools before you even started on this job. Without that, there isn't much we can do to help you.

Good news is, VCDS is cheap. Really cheap, and really easy to use.

the throttle pedal has absolutly no responce when in gear,

the original job was a broken timing belt which lead to replacing the worn out cam, when the belt broke the car was doing 60 mph so there was no problem with the throttle at that time, when you say VCDS is cheap, how cheap, like $20.00 or $300.00 or more?

this will be a one time job so i do not intend to spend on stuff i will never need after this car!

the owner tells me that there was no cel on before the belt broke.

i have ordered a new fuel temp sensor.

this is not a lack of fuel, its a communication problem when in gear and the ECM is stopping the throttle responce to the injectors.

my next thing to change is the brake light switch.

as a very long time vehicle technician at ASE master level, i am not green, so yes, the VCDS diagnostic tool would be of considerable help but to be honest, totally impractical in this situation.

does anyone think that bridging the 2-3 terminals on the brake light switch plug would rule that out?

A VCDS (Vag-Com) is $350 for the model that will do everything you need to the 1996+ (1990+ if you have the 2x2 patch cable) VW & Audi cars. It's well worth it if you work on any of them, even the gassers.

I will defer to the experts on jumping the brake switches since I typically work on the Mk3 and some Mk4 platforms only.

But to say it would be totally impractical in this situation is not accurate, it would probably tell you exactly what the problem is.

It is about one 20th the cost of the same level of scan tool for any other make of car.

But go ahead and chase your tail if you like. That isn't very professional, from one ASE L1 Master Tech to another.

Like I said, you shouldn't have taken on this job if you don't have the proper tools. I suspect other parts of the job have been done wrong, too, as I doubt you got the tools for that stuff as well as addressed the chain in the bowels of the engine.

Do the brake lights come on when you depress the pedal? Have you made sure that everything was plugged back in when you put it back together?

Mr. Hammer,

it was my intension to rebuild the whole engine but my friend who owns the car refused to pay for the parts or even a good used drop out.

and as far as the right tools, well i've got a flat blade scewdriver with a broken handle from the swap meet, two pairs of vice grips, both large and small that i picked up at a yard sale, they were a bit rusty i must admit, and my buddy lent me a framing hammer so i'm good to go.

and i used all the old bolts to put it back together, just ran a lock nut down them where the threads were a bit stretched, and my mate's angle grinder soon got the cam cleaned up so that got stuffed back in as well, i was going to pack the cam bearings with a coke can but i only had pepsi and i heard that doesn't work so i put the top bearings in the bottom and the bottom bearing in the top, i read that on the internet.

as far as the bent valves go, i managed to straighten them in a vice but lost some of the keepers so i got them welded on now, if its good enough for puting the head back on one of the valves then its good enough to hold the springs in place.

You come on here, Mr. ASE certified Master technician, asking for help and when suggestions are made you cop an attitude. "Mr. Hammer" as you refer to him has forgotten more about cars, VW TDIs in particular, than you will ever know.

Figure it out yourself, asshat.

1854Sailor, if only you knew.

i'm sure that if Oilhammer was offended by my comments, he would say so, i would think he is a bit thicker skinned than that, especially as i said nothing about him, his abillities, skill set or his tools.

clearly you are not, but thats not my problem, its yours.

"asshat", i've got to laugh at that one, John Cooper said something similar to me in about 1968 but it ended in "hole".

john hennessy said:

Mr. Hammer,

it was my intension to rebuild the whole engine but my friend who owns the car refused to pay for the parts or even a good used drop out.

and as far as the right tools, well i've got a flat blade scewdriver with a broken handle from the swap meet, two pairs of vice grips, both large and small that i picked up at a yard sale, they were a bit rusty i must admit, and my buddy lent me a framing hammer so i'm good to go.

and i used all the old bolts to put it back together, just ran a lock nut down them where the threads were a bit stretched, and my mate's angle grinder soon got the cam cleaned up so that got stuffed back in as well, i was going to pack the cam bearings with a coke can but i only had pepsi and i heard that doesn't work so i put the top bearings in the bottom and the bottom bearing in the top, i read that on the internet.

as far as the bent valves go, i managed to straighten them in a vice but lost some of the keepers so i got them welded on now, if its good enough for puting the head back on one of the valves then its good enough to hold the springs in place.

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I think the Dry heat got to you!
Folks on here don't do what you are doing.
Be nice
Maybe now you know everything but there will come a day when you wont!
The vise you used was drugs?

peiphil, read oilhammers last post and maybe you will respond to him in the same way.

all i did was refer to oilhammer as Mr hammer, and i used the term "Mr" out of respect, in view of his comments about the way i probably didn't do the job right, continued with the same theme and poke fun at myself and my tools and methods.

there was no call for him to do that or indeed anyone else to comment on his behalf, if i offended anyone well so be it but look at what you are writing,

there is no call for you to make comments about drugs or the heat getting to me and there is no need for 1854sailor to call me asshat or oilhammer to say that i probably did the whole job wrong either.

i have located a vcds about 65 miles away so there you go, i have the tools in my box.

kindest regards, John Hennessy

John.. do you by chance do also spend some time on "viper alley". If so you will soon see many here are much thinner skinned than over there and the constant ribbing that goes on there doesn't here. Nothing wrong with that in my opinion it's just a different type of car enthusiast/personality over here. For the most part everyone here is very helpful and while there are a few that there typing ability is much better than there actual car knowledge I assure you Oilhammer is definitely not one of them. He is one of the most knowledgeable on the forum and is very well informed on VW products. You can take his input as fact. Get the car scanned via VCDS and post your findings here and I'm sure collectively we can help with your issues. If your not an alley member you share a user name with someone over there lol. yes I'm a viper enthusiast/owner also if it is you

I for one would like to find out what the cause of this issue is. Hopefully the PO will comment again....I mean OP. oops

RSMS, thats a different John Hennessy i'm afraid.

i have spent most of my life in Europe, where after college i worked for many years in the defence industry but with a passion for high performance cars, in every country that i have worked there has always been a form of commradeship between mechanics but there are always some that, although excellent at their job are not the easiest to get on with but i try not to ruffle too many feathers.

as i have said in earlier posts, i agree with oilhammer, had i known that there was a diagnostic problem i would have approached the job in a completely different manner, alas that was not the case but until the car was back together, there was no way of telling what mayhem would rear its ugly head.

i also think that due to the car having sat for about 5 months with a flat battery, a problem i was not aware of at the outset, that this is part of the problem.

clearly, you cannot trust the owner to be completely honest, this may also apply to any codes that were present before the cam belt broke, and given the wear factor in the valve train and 109000 miles without a belt change, i now have a different outlook to the job.

the fuel temp sensor is on its way, until that arrives, there is not much i can do, once installed, i will take the car to someone who has and uses the vagcom diagnostic equipment regularly, he is a former trainee of mine and requires nothing for his assistance.

the only problem is i have to get it on a trailer and with almost no throttle this may proove a challenge but not insurmountable.

i will also be in california for two days this weekend as a pre cursor to testing at Montery, so i may not post the results of the scan for some time, i may be able to get out of the Monterey thing after this weekend so that may speed things along.

Once scanned with a VCDS you can go to the Ross Tech website(the company that produces the VCDS) and look at his wiki page, it will provide you with a good place to start on diagnosing the issue. If you still are drawing a blank there is a lot of good knowledge on this site, it has taught me a lot in working on VW's. I'm guessing neither you or the owner are familiar with the balance shaft module issue these cars so if he is planning on keeping it you or him might want to do a little reading up on it. With the miles it has this is something that should be addressed or atleast known about. I've had them fail with less miles and also had many go much longer with only being noisy and vibrating. Good luck with it

i changed the fuel temp sensor but the code remained P0183,

what can i look for as far as voltage at the sensor plugs

hold that thought,

i just unpluged the fuel temp sensor and turned the plug over to do a voltage test and what do you know, it came right out with about six inches of wire attached.

i soldered the wires back together and covered with heat shrink, checked for codes and pending codes there were none.

this was because when i run it on Vagcom i don't want any codes that i could fix first as reading the test proceedure, i says that no codes can be present to sync the throttle.

hopefully, this week i can get it scanned, then we will know for sure if the brake light switch or anything else is stopping communication with the throttle pedal.

Just for reference temp senders in most cases get a 5 volt feed with a pull down resister in series from the ecu.
The ecu then measures how far the temp sensor (thermistor) pulls that voltage down to the correct reading.
If the ecu sees the full 5 volts it knows that the circuit is broken unless its -40 out side and engine coolant sensor agrees
If the eccu sees 0 volts it sees that as a shorted sensor or shorted wire to it.
If the sensor is a one wire type do not use Teflon tape on the threads as it will prevent the sensor from getting a good ground.

peiphil,

so am i reading you right,

the lower the temp, the higher the voltage output back to the ecu?

if you have 5 volts ref. from the ecu to the temp sensor, and this wire is shorted to the other wire returning to the ecu ( the wire the voltage should change on if the temp changes) the ecu will see 5 volt, thus stating "fuel temp a circuit too high" and set code P0183?

if the ref voltage wire is shorted to ground, (difficult to actually happen") then the voltage collapses at that point in the wire and is lost so it sees 0 volts.

so when testing, if 5 volts are present at the ecu pin but 0 volts at the sensor plug then the ref voltage wire is broken between the two.

if the return wire is broken, the ecu will see no return voltage, if voltage at the sensor shows 5 volts on one wire and some lower voltage on the other when plugged into the sensor or jumped, the break would be in the return wire and show no voltage at the ecu.

the sensor itself would be difficult to short to ground as it is plastic and free floatig in a rubber hose.

it could go "open circuit" at which point back probing the sensor plug would show 5 volts on one wire and 0 volts on the other, or infinity in resistance across the sender.

i have no reason to believe that the sensor could or would ever show 0 ohms resitance but if it did, you would have 5 volts on both terminals of the sensor when plugged in and back probed, if this case arrises unplug the sensor, and voltage should disappear from one wire, if it doesn't then the wire is shorted.

the only other option would be if the ecu were to output 5 volts down both wires, i have seen this on some ecu's with a common internal return from more than one sensor, i do not know if the tdi has such an internal circuit.

One wire is ground negative never mind it as long as it does in fact have good continuity to ground.
The other wire when unplugged you will see the 5 volts from ecu
When you plug it back in you will see 2 to 3 volts depending on temperature at the time if you back probe the connector with your meter
The thermistor pulls the voltage down in varying amounts and that's what the ecm reads.
Its not like it is sending a signal back from another wire but just pulls the voltage down on one wire because of the pulldown resister in series with the 5 volt output.
The sensor should read a few thousand ohms depending on ambient temperature
Never 0

There was at least one recall on brake light switches and as I remember they are also color coded as to which reincarnation they are as well. Sure sounds like the classic switch failure. This thread has really gone wild.

If the brake light switch failed, the brake lighys would be on all the time.

Without looking, I seemed to remember there were more than two wires at the switch. I may well be mistaken, but it appears that the ecu is getting a b+ from that switch, preventing throttle response in anything except P and N.

thundershorts said:

Without looking, I seemed to remember there were more than two wires at the switch. I may well be mistaken, but it appears that the ecu is getting a b+ from that switch, preventing throttle response in anything except P and N.

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TS, correct.
F47 is normally closed, and connect A15 (+12v connection) to ECU pin T94/65
If F47 fails, and no 12v is present on T94/65, I think it will prevent any throttle response in D or R

Thanks Charlie for going to the trouble to confirm that I'm not totally senile. The brake light switches were a big problem for awhile, often sticking on and discharging the battery. VW apparently then color coded them for easy identification. My donor car had had the switch recall and I used the switch which had different color markings. In this particular vehicle in question, it may still have the original crappy switch. I'd simply buy a new switch at a dealership, not aftermarket, and the appearance should be obvious. Installation should take less than a minute,