99.5 "New" Jetta Throttle body won't adapt

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  #1  
Old 08-08-10, 09:20 AM
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99.5 "New" Jetta Throttle body won't adapt

I've been struggling with this for awhile, here's what has been done;

Original TB with 120K miles, gave the CEL..code is P1565: "No low idle speed reached"

Dealer said it needed a new throttle body, however all of this happened after the battery was disconnected and the TB was cleaned...by myself. TB is spotless now...NOTHING entered where it shouldn't have. I can only think that with the residue on the TB housing around the butterfly, the ECU had to "learn" a new idle position because of the air restriction from the gunk and had to open the butterfly slightly.

So I looked around and found a few procedures to try. I disconnected the battery, drained the residual current from the vehicle confirmed by a DMM. Went from .40 mv to .01 reading from the car cables..no battery attached.

Codes cleared, hooked the battery, turned key to ON, waited until TB stopped making noises, waited another 10 min, started car, did not touch the gas pedal this entire time. Let idle for 10 min, drove around, when I shut the car off and restarted, the CEL came back on but did not turn on while driving.

When a VAG COM is connected it reads "Error" when starting the adaptation process. I purchased a used TB but this is from the same AEG engine with the same accessories, incl cruise control, same deal...starts fine, runs fine but same code and same error when adapting.

Checked ECU and all the pins are clean, no corrosion and tight.

I opened the plastic cover and checked inside and is spotless. I applied a spacer inbetween the throttle arm and stop to further close butterfly...about a .020 gap and it still idles at 825 RPM +- 25 and throws the code. I measured the ohms when turning the throttle plate, very linear and smooth, even when I push against the spring to further close it.

I cannot get a new dealer TB to test, I don't want to spend upwards of $800-1000 to have it replaced. I feel there is another issue and not the TB...could be wrong so if anyone knows these systems well please chime in.

TB is cable driven not DBW. Engine is 2.0 AEG AUTO/Cruise.

Wanted to add the correct definition of the P1565 code is:

"Idle Speed Control Throttle Position Lower Limit Not Obtained" However it idles at the proper speed.
 

Last edited by i6pwr; 08-08-10 at 09:37 AM.
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  #2  
Old 08-08-10, 09:25 PM
Join Date: Jul 2009
Location: Washington State
Posts: 312
It could be not enough time in the drive cycle but since you have no way of a live emission readiness verification this may help.Since you have disconnected the battery and cleared all memory in the ECM. Gotta love drive by wire huh(My car has it too)

Begin Drive Cycle
The vehicle should be driven approximately 7.5 miles within a period of approx. 23 minutes (1372 seconds) from a cold start. However, due to manufacture variations, it is necessary to perform only as much of the Drive Cycle as is necessary to reset the required monitors to a "Ready" status. Operate the throttle smoothly to obtain best results. Do not shut the engine off during the drive cycle.

CAUTION: Obey all traffic laws and drive in a safe manner!

NOTE: Extreme driving conditioning such as very high/low temperatures, rough roads and high altitudes may prevent some monitors from attaining a "Ready" status.

Step 1 (Engine Cold) Start engine, idle 20 seconds. Accelerate gradually and drive at 20-25 mph for 1 minute, varying speed.
Step 2 Accelerate gradually to 32 mph within 35 seconds. Decelerate to 0 mph in 10 seconds. Idle for 40 seconds.
Step 3 Accelerate at part throttle to 25 mph in 10 seconds. Cruise at 17-25 mph for 15 seconds. Accelerate gradually to 57 mph in 45 seconds. Cruise at 50-56 mph for 1 minute. Decelerate gradually to 0 mph in 40 seconds. Idle for 15 seconds.
Step 4 Accelerate at part throttle to 36 mph and maintain for 10 seconds. Decelerate to 0 mph in 15 seconds. Idle for 5 seconds.
Step 5 Accelerate to 30 mph and back to 0 mph within 30 seconds. Idle for 20 seconds.
Step 6 Accelerate to 36 mph in 20 seconds. Drive at 35 mph for 20 seconds. Decelerate to 0 mph in 15 seconds. Idle 5 seconds.
Step 7 Accelerate gradually to 26 mph and decelerate to 0 within 40 seconds. Idle 15 seconds.
Step 8 Accelerate to 27 mph in 40 seconds. Decelerate to 0 mph in 10 seconds. Idle 25 seconds.
Step 9 Accelerate to 26 mph in 15 seconds, maintain speed for 10 seconds, decelerate to 0 mph in 10 seconds. Idle 15 seconds.
Step 10 Accelerate to 23 mph in 20 seconds, decelerate to 0.5 mph in 10 seconds (no complete stop). Accelerate to 28 mph and back to 0 mph (momentary stop 1 second) within 35 seconds.
Step 11 Accelerate gradually to 34 mph in 45 seconds. Vary speed between 34 and 19 mph for 2 minutes. Decelerate from 25 to 0 mph in 25 seconds. Idle for 5 seconds.
Step 12 Accelerate to 29 mph in 15 seconds, decelerate gradually to 0 mph in 45 seconds. Idle for 30 seconds.
Step 13 Accelerate gradually to 28 mph and back to 0 mph (momentary stop 1 second) within 50 seconds. Accelerate gradually to 27 mph and back to 0 mph within 55 seconds. Idle for 15 seconds.
Step 14 Accelerate to 24 mph and back to 0 mph within 18 seconds. Idle for 10 seconds. Accelerate gradually to 22 mph and back to 0 mph within 50 seconds. Idle for 8 seconds.
Step 15 Accelerate gradually to 30 mph within 50 seconds. Decelerate to 0 mph in 10 seconds. Idle for 25 seconds.
Step 16 Accelerate to 23 mph and back to 0 mph within 30 seconds. Idle for 10 seconds.
Step 17 Repeat steps 1 - 16 once again. Recheck the status of the "Readiness Monitors".

NOTE: Remember, clearing DTC's or interrupting power to the ECM after the readiness monitors have been reset to "Ready" will require that the Drive Cycle be repeated.

Completing the Drive Cycle successfully one (1) time should reset most drive cycle monitors to a "Ready" status. However, there are "two trip" monitors, which require that the drive cycle be successfully completed two (2) times, to achieve a "Ready" status. Furthermore, systems which use averaging, may require the drive cycle to be completed more than 2 times. It is necessary to perform only as much of the Drive Cycle as is necessary to reset the required monitors to a "Ready" status.
Kind of a pain but this is the procedure for yours with the L4 2.0 AEG Since you have already covered all the other recommended things the only thing left in the diag flow chart is faulty ECM that would cause this problem.
Good Luck
 
  #3  
Old 08-08-10, 10:20 PM
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Is sounds like you know how to use a multimeter, etc...

You can order the factory electrical diagrams as part of the factory service manual set of books. Then when looking at the electrical diagrams, it is a WHOLE lot easier to find the problem, especially if you know electronics.

I don't know what that specific trouble code is monitoring or looking for, but there may be a throttle position switch or throttle position sensor or idle air control valve which is monitored by certain wires. And when closed or at low idle, maybe those wires want to see a certain resistance...

Maybe there is just a loose connection in a connector? And the engine computer is not seeing [whatever] close all the way or not seeing the resistance it expects to see?

Or perhaps there is a fuse blown and that powers a circuit or IC chips on a throttle body control, and because there is no power to that device, it can't send a "closed" signal to the engine computer???

I'm just wildly guessing, but that is the way these things work. They look for a certain resistance or signal to indicate things are working. If that signal can't get through to the engine computer, then you will get the trouble code.

Then the newer the vehicle is, the more computer modules you have. There could be several computers. One might just "pass the message along" from the throttle body to the engine computer (computer network stuff)... Anyway if that "in-between" computer has its fuse blown, then it can't pass the message along!

Anyway helps to look at the wiring diagrams and read the description of operation, then that might give you additional troubleshooting/testing ideas...
 
  #4  
Old 08-09-10, 02:51 AM
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That's one serious driving cycle GI2...gonna look odd on the interstate

Well, I noticed you said "drive by wire", you may have overlooked my post that this is cable driven TB not drive by wire. Does this procedure apply to the cable TB?

I will give it a try on a cold motor though.

I did check the connections but will try again on all of them. I believe there is no IAC valve or TPS...it's all in the stepper motor of the TB. Cable driven but regulated by a stepper motor as well.
 
  #5  
Old 08-09-10, 08:50 PM
Join Date: Jul 2009
Location: Washington State
Posts: 312
Ya my bust did look up the procedure for the 2.0 AEG though.I am fortunate enough to have a few "back roads" around the shop to run customers cars in with out worry's from the local five o LOL.
 
  #6  
Old 11-07-10, 09:09 AM
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**solved**

Never did the driving cycle, I appreciate the effort in posting but never reached that point. Car sat until yesterday but in the meantime I drove it a few times. Spoke with a buddy who really knows VW's in and out, and I also took advice from another VW tech on cleaning all the grounds under the battery tray which were somewhat corroded.

After the cleaning, sanding, etc, the TB still would not adapt. Removed the 2nd TB and reconnected the original which started this whole mess. My buddy added another ground wire from the neg cable to one of the existing grounding points, seems these cars are very sensitive to voltage and good, clean grounds make them very happy.

I'm willing to bet that without the extra ground that it may have worked, but there is a threaded post on the cable and not sure why, but we used it for another ground and the original TB adapted and all is good.

The car is currently in the same condition (with the addition of the ground) as it was when the dealer told me I will need a new TB before too long...($700+labor).

After my 2nd and 3rd attempts for the dealer to adapt the TB, they both told me I needed a new TB, but could not test a new one. Being almost 11 years old now i'm sure the wires develop corrosion being in the elements, could be numerous areas where voltage has dropped slightly but kinda disturbs me I was almost out a grand for this.

Not calling anyone a crook since I didn't have a new one installed but nothing was really ever wrong with the TB to begin with. They could have tried a new one and it may not have adapted, who knows but anyone with this issue be sure to THROUGHLY clean and sand all the grounds under the tray or wherever they may be.

Runs like a champ.
 
  #7  
Old 06-09-13, 02:58 PM
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2000 VW Jetta GLS 2.0 TB issue

i6pwr - I'm having the same exact TB issue that you had with my daughter's a 2000 VW Jetta ("Idle Speed Control Throttle Position Lower Limit Not Obtained"). Same error with both old and new TB. You indicated that your buddy added another ground wire from the neg cable to one of the existing grounding points. I'm wondering where the additional ground wire was connected from and to. Is this on the TB itself? Do you have a pic you can post?
 
  #8  
Old 06-10-13, 05:13 AM
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Join Date: Jan 2012
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i6pwr - I'm having the same exact TB issue that you had with my daughter's a 2000 VW Jetta ("Idle Speed Control Throttle Position Lower Limit Not Obtained"). Same error with both old and new TB. You indicated that your buddy added another ground wire from the neg cable to one of the existing grounding points. I'm wondering where the additional ground wire was connected from and to. Is this on the TB itself? Do you have a pic you can post?
Welcome to the forum.
You may want to consider starting your own thread and referencing this thread.

On a side note, I've replaced ground wires with new ones (using car audio power wire) and it has done a world of difference on the vehicles I've done this on. It's more then likely the clean contacts that makes the difference.
 
  #9  
Old 07-13-13, 10:20 AM
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Sent you a PM

Also, make sure your TB is clean. I would advise against unplugging the harness if possible.
 
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