01 beetle drive by wire problem

Hey guys I am back with another head scratcher. I have a 01 VW Beetle with a 2.0 with a AVH engine code. This started about a month ago when when the car went into limp mode and I scoped the TPS and it was very erratic so he (customer) changed it about a moth ago and now it has a 17950 or a P1542 code. g187 not a plausable signal. Here is where I am having trouble when I scope both sensors in the throttle body I have nice clean symmetrical signals with no drop outs or glitches, when I turn on peak detect the signals have alot of hash but seem to coincide with each other. Peak detect on I have voltages spikes up to 8 volts like I said before with no peak detect its steady and smooth. The other concern is the throttle body motor has a high pitch whine sorta like a hair dryer I am not sure if this is normal but I never heard that on any other DBW system.
I put the scope on FREQ. and its all over the place connected to the sensors. I would expect that on the motor but there shouldnt be any kind of freq on a sensor should there?
Checked the AC voltage on the alternator and its around .002 and with peak detect on it has spikes up to 1.5V AC with a lot of hash.
The customer literally changed just about everything for other non related problems so I want to be accurate with my diag.

Thanks for all the help I really appreciate it..

John Hufnagel

Yo John! Just curious, did you ever hear back about the Chevy truck that was misfiring?

Yep, you guessed it, wiring diagram:



The plausible signal code kinda makes me wonder about F60, the closed throttle position switch. It makes sense to me that if your throttle potentiometers were sweeping normally (which is sounds like they are), but the CTP was saying the throttle is closed, then the computer would set a rationality code like this P1542.

Also wondering about the motor noise you described... Can you make the throttle plate sweep closed to open with the gas pedal? It honestly sounds like the motor is jammed up or binding, maybe disconnect the throttle body and try moving the plate manually, see if it swings freely.

Thats weird I did not see a CTP on the diagram I have from Mitchel or Snap On Guided component tests. I will defiantly look tomorrow. The throttle blade moves nice with no binding or anything with the gas pedal.
The noise is constant while the throttle body is awake. after about 10-20 seconds of no movement the TB goes to "sleep mode" or something like that the noise stops and the power is shut down to the blade motor soon as I touch the pedal it wakes up.

No I haven't had the time to look at the truck again I just got my pico with WPS500 last week and haven't had much time to mess with it either, but soon as I do will let yinz know

That is weird. I pulled up the component test info on my Verus and it shows a 6 pin connector. No mention of a closed throttle position sense circuit.
For what it's worth, there was just one of these at the shop, and it also made a whine from the throttle assembly KOEO. Doesn't make it right, just an observation.

johnphufnagal wrote:

Update
The car is fixed! After spending all day on this on my only day off, I could not find a problem with the electronic throttle, so I texted my buddy Joe that owns Bullseye auto. The first thing he asked me if I did a relearn for the new throttle body that the customer changed a month ago. And of course I didn't, I never even thought about it, He says before doing anything else do the relearn!! So he very quickly gave me instructions on how to do it. something about using "word address 33" and changing a few thing, so I checked it out and I was over my head doing something like this and did not feel comfortable because I was getting all kinds of warnings about changing something and the car could be disabled and not run. So I got out of there and found a PID for throttle relearn.
I did the relearn and took the car for 15 mile drive and the EPC or check engine light never came on. Until I pulled in my driveway and the engine light come on, so I scanned it and to my relief I have the dreaded P0420 code and thats it!! He was already aware of it.

I know I didn't get much input on my problem but thats ok because I would rather not get any help than have a bunch of people telling me to change everything until I find the problem. LOL

Thanks Guys

Great, always nce to wrap these up with a confirmed fix!

I know I didn't get much input on my problem but thats ok because I would rather not get any help than have a bunch of people telling me to change everything until I find the problem. LOL

Thanks Guys

Yeah, that's never fun is it? Thankfully, you won't get much advice on this forum that starts with "why don't you try changing the..."

Did you every verify the presence of a CTP pin on the connector? Just curious, doesn't really matter at this point.

Sorry for butchering your post brother...
All I wanted to do was add [FIXED] to the title, need more practice!