Volkswagen Passat Forum banner
1 - 20 of 26 Posts

·
Registered
Joined
·
14 Posts
Discussion Starter · #1 ·
Hi

i have been having a problem with my 1999 VW Passat 1.8T Sport DBW.

It intermittantly stutters on acceleration then throws a code

Accelerator Position Sensor 1/2: Implausible signal

However this does not happen all the time. Only every once in a while.

I'm presuming its the pedal as i recently had a flood in my battery compartment and some water leaked into the drivers side footwell.

I noticed that the following thread mentioned that the item was $70

http://www.passatworld.com/forums/sh...i tion+Sensor

has anyone got a part number for this?

Has anyone else had this problem before?

Cheers
 

·
Registered
Joined
·
6,172 Posts
Welcome to PW! :)

That part is most likely the problem. It should be a plug-and-play replacement; however, you may want to try just cleaning the contacts on the connection before replacing the part.

Are you sure it doesn't say "Throttle position sensor 1/2: Implausible Signal"? That would be a much more expensive repair. (Based on your recent flooding, this is unlikely the problem, however). Do you have the actual "error code"?

I'm away from my parts database, but I'm sure someone will have a P/N shortly...
 

·
Registered
Joined
·
14 Posts
Discussion Starter · #3 ·
Cheers for your help on this one

Here's the actual error code i pulled from VAG COM

18047 - Accelerator Position Sensor 1/2 (G79/G185): Implausible Signal
P1639 - 35-10 - - - Intermittent
 

·
Registered
Joined
·
14 Posts
Discussion Starter · #5 ·
"That part is most likely the problem. It should be a plug-and-play replacement;however, you may want to try just cleaning the contacts on the connection before replacing the part."

Where would i be able to locate this part? Where is it on the car? Is it the one attached to the pedal?

"Are you sure it doesn't say "Throttle position sensor 1/2: Implausible Signal"? That would be a much more expensive repair. (Based on your recent flooding, this is unlikely the problem, however). Do you have the actual "error code"?"

You mention that based on the recent flooding it is unlikely the expensive part. Why is this? Is it located somewhere else? The only reason i ask is because i am having difficulties identifying which part is which on the car.

Again your time is much appreciated.

Thanks
 

·
Registered
Joined
·
3,559 Posts
The throttle position sensor (G79) and the accelerator postion sensor (G185) are in the same housing on the accelerator pedal assembly.
 

·
Registered
Joined
·
6,172 Posts
okay, I finally found the relevant sections in my bentley. PM me your email address & I'll forward you the section with the exploded view of the throttle position sensor & the section with the kick-down adaptation procedure (reqired after replacing the sensor unit).

as kenblasko said above, there are two sensors inside one unit attached to the top of the accelerator pedal shaft.

tell me your model year, engine & engine code & I'll try to find a part number.
 

·
Registered
Joined
·
6,172 Posts
Is this the expensive part? Has anyone got a a PN for this?
Okay, I emailed the .pdf of the accelerator pedal assembly.

I need your model year and engine code to find a correct part number. The engine code is stamped on the lifting lug located underneath the black plastic engine cover (US-spec 1.8T's are either AEB, ATW, AUG, or AWM. US-spec V6's are either AHA or ATQ). :thumbup:
 

·
Registered
Joined
·
14 Posts
Discussion Starter · #11 ·
This isn't looking good.

Tried cleaning the contacts with electrical spray cleaner now its coming on with a permanent EPC light with the following error

Throttle position sensor (G79) too high

Bought a pedal assembly and it didnt change anything. light still stays permanently on.

i cannot clear the code either with vag com.

i tried to monitor group 062 and noticed that the throttle position is operating out of spec at 99.2% (should be between 12% and 97%)

would the electrical cleaner mess anything up? i thought stuff like that is inert.

Am i missing something obvious here?

I'm tearing my hair out over this and i need to get this sorted asap as i need the car for xmas.

Any ideas anyone?
 

·
Registered
Joined
·
6,172 Posts
VW tends to issue engine codes with the second letter increasing in alphabetical order, so I'd expect your APU engine is most-similar to the US-Spec ATW (drive-by-wire, no variable cam timing).

Electrical cleaner should be the right stuff.

Try using the "vag-scope" to graph measuring block 062. The output in fields 3 & 4 should mimic the movement of the accelerator pedal in a "linear" fashion: moving from 0 to 1/2 throttle should cause the same change as moving from 1/2 to full throttle.

What error codes are currently showing? Still just P1639?

Is the "Check-Engine" light on all the time (picture of an engine), or is it the "EPC" light that is on?

Take a look at the .pdf I emailed you. In particular, the section "Checking voltage supply and wiring to control module". Use a multimeter to check the voltage at the pins on the engine-side of the wiring connector, following the instructions in that .pdf file. I expect you have a short to ground somewhere.

By the way, the 12% to 97% spec for the sensor output is for idling-conditions only... I think they discuss it some more in the .pdf file.

I wonder if you need to do a "kick-down adaptation", even though you have a manual transmission. Hmmm.
 

·
Registered
Joined
·
14 Posts
Discussion Starter · #13 ·
how do i post images???

I have taken a print screen of the message blocks when i go into block 062 if i press the accelerator pedal down data from 1,2 and 4 move but 3 (throttle pos) stays at 99.4% (sometime it fluctuats between 99.2% and 99.6% but i'm sure thats wrong??)

any ideas?

what a nightmare for a noob to this forum!!!
 

·
Registered
Joined
·
14 Posts
Discussion Starter · #14 ·
btw its the EPC light that stays on all the time.

heres what i pulled from VAG COM

18039 - Accelerator Position Sensor (G79): Signal too High
P1631 - 35-00 - -

all i did was take the old pedal off clean the connectors with electrical spray cleaner then put the new pedal on. do you think this could have caused the problem?

Cheers
 

·
Registered
Joined
·
14 Posts
Discussion Starter · #15 ·
Okay I tested the wires and here are the results:-

- Connect multimeter to the following connector terminals for voltage measurement.
Terminal 1 + Ground (GND) 5.04v
Terminal 1 + 5 5.06v
Terminal 2 + Ground (GND) 5.04v
Terminal 2 + 3 0.00v
Specification: at least 4.5 V

one thing regarding the above test... I forgot to turn on the ignition so this test might be invalid.

looks like something is up with terminals 2 + 3 voltage wise possibly

- Also check wires for short circuits to B+ or Ground (GND).
- Also check wires for short circuit to each other.

these were both okay i think

Do you think this could be a problem with the ECU considering i have put in a brand new pedal assembly?
 

·
Registered
Joined
·
6,172 Posts
I think one of the wires from the ECU is damaged where it plugs into the back of pin 3 on the 6-pin connector. Try peeling back just a little bit of insulation on that wire and checking it again w/ the multimeter. BTW, the ignition should be switched "ON", but with the engine not running, when you check these voltages.

Pins 1, 2, and 5 seem okay.

I'll try to find the wiring diagrams today & see where that wire connects on the ECU. I think that this can still be fixed by rewiring the connector, or, worst case, replacing just that one wire from the ECU, too.
 

·
Registered
Joined
·
14 Posts
Discussion Starter · #17 ·
Could i just make up a 6 wire loom and feed directly from the ecu to the pedal?

You mention that Pins 1, 2, and 5 seem okay. Do you suspect its pin 3 or pin 3 and 6?
 

·
Registered
Joined
·
3,559 Posts
Could i just make up a 6 wire loom and feed directly from the ecu to the pedal?

You mention that Pins 1, 2, and 5 seem okay. Do you suspect its pin 3 or pin 3 and 6?
Before you make up a harness, did you check the continuity of the wires from the sensor connector to the ECM connector? When you have both connectors off to check the continuity of the wires, also recheck for shorts between the wires and between each wire and ground and check that battery voltage is not present on any wire. If you have continuity, no shorts, and no battery voltage, then wires are good.
 

·
Registered
Joined
·
14 Posts
Discussion Starter · #19 ·
Problem solved!!!! Pete your assumptions were correct. It WAS wire 3!

Basically the connector that goes to the wiring loom pin 3 had been pushed in so it was slowly starting to have a intermittant contact i.e. when i had the flood. But then it finally gave up the ghost when i put electrical cleaner on it and the spary from it was enough to push up the whole pin 3 socket into the connector.

Just as well i found it when i did as i was going to send off the ECU for a repair!

A BIG thanks for pete1 in being very knowledgeful and patient with me pestering him for ideas and a thanks to kenblasko for putting some ideas in the mix!
 

·
Registered
Joined
·
6,172 Posts
I love a happy ending!!! :)
 
1 - 20 of 26 Posts
Top