Audi Q7 2007 4.2 TDi BTR Engine

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Audi Q7 2007 4.2 TDi BTR Engine

Postby STC » Fri Aug 26, 2016 5:49 pm

The fault code I have is
01273 - Fresh Air Blower (V2)
010 - Open or Short to Plus
Freeze Frame:
Fault Status: 01101010
Fault Priority: 3
Fault Frequency: 1
Reset counter: 91
Mileage: 138043 km
Time Indication: 0
Date: 2016.08.26
Time: 17:03:07

Freeze Frame:
Temperature: 41.0°C
Speed: 0.0 km/h
(no units): 185.0
Load: 0.0 %
Q7 Blower Control.png

Audi_Q7_2007_Blower Control.psdata
(331.3 KiB) Downloaded 15 times

As you can see the fan runs correctly at all 12 speeds, the issue is that it stops the Air con Compressor from engaging.
Clear the code and it will engage for about 10 seconds and kick out again.

This is climate but does not have the additional rear blower.

J126, J255 and V2 are Genuine new. I have seen the invoice with the correct Reg no.
I am convinced that the issue is the feedback wire. The terminal on J126 is marked "DIAG"
Unplugging the Fan V2 or the control Unit J126 or both does not entice additional DTC's. That's some reassurance that I am on the right track.

SSP361 page 66 - 67
Fresh air blower control unit J126
The fresh air blower control unit J126 controls the
blower speed in the deluxe automatic air conditioner
and the four-zone deluxe automatic air conditioner.
In the manual system, a series resistor is installed in
its place.
The sender is activated by the Climatronic control
unit J255 via an analogue signal.


Networking
The Climatronic control unit J255 is connected to the convenience CAN bus, It is the master control unit for
the distributed functions of the heated rear window, the optional heated seats, the additional heater in the
case of diesel engines, as well as the optional, factory-installed auxiliary heater.
The Climatronic control unit J255 does not control any modules connected to the LIN bus. The fresh air blower
control unit J126 and the high pressure sender G65 are not connected to the LIN bus. Serial data telegrams
(PWM signals) are used.


SSP 301 Page 73
Sender for
blower control, front G462
In the 4C-Climatronic and the 2CClimatronic,
this is inserted immediately next to
the blower in the housing of the air-conditioning
unit and secured by two screws. In the manual
air-conditioning system, a protective resistor is
installed in place of the regulator.

Function
The sender for blower control is activated by the
Climatronic control unit using a pulse widthmodulated
signal (PWM).
Power is supplied to the control by the
Climatronic control unit J255.
According to its demands, the sender regulates
the blower motor in the air-conditioning unit.

Effect of drop-out
If a blower is defective, the entire heating and
cooling function of the air-conditioning system
fails.
The diagnostics can be used only indirectly to
localise a fault on the blower control unit or on
the blower. For this purpose, there is a resistor in
the blower control unit; this is connected with the
minus pole of the blower motor.
Due to this arrangement, the control unit receives
”acknowledgement information”, which can be
used to determine whether the fault is at the
sender, at the blower or both.
There is no direct indication for a fault on the
control or on the blower.
However, the voltage signal of the resistor in the
blower control is not a signal for the actual
voltage on the blower motor, but rather a signal
with which the Climatronic control unit can
”observe” the behaviour of the sender for the
blower control.


With a view to pin the fault on either J126 or J255 I cut the feedback wire and scoped both ends of it
Last edited by STC on Sun Sep 04, 2016 12:27 pm, edited 3 times in total.
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Re: Audi Q7 2007 4.2 TDi BTR Engine

Postby STC » Fri Aug 26, 2016 6:57 pm

With wire Cut

Q7 fan control with wire cut.png

Audi_Q7_2007_Wire cut.psdata
(192.02 KiB) Downloaded 13 times


I think what I need is a known good to go any further if anyone can help ?
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Re: Audi Q7 2007 4.2 TDi BTR Engine

Postby dieseljohnny » Fri Aug 26, 2016 7:06 pm

Hi again STC.

Could you post the screen you see when you enter air conditioning in vcds..

In measuring value block 2 section 1 does it say 26?
Could you post all four sections of block 2

Can you do basic setting on block 6, 1 and 3?

Try 6 first as it's to do with the motor characteristics.

If j255 was replaced basic setting on block 1 then 3 must be done before air-conditioning will function but that usually has a basic setting not done fault stored


Also what's happening on measuring value blocks 45 and 46? The

Afound info relating to a modified v2,j255 and matching j126 after the 11/2007 that's aren't compatible with the older versions.
So might be worth checking part numbers

Also found information on the feedback wire but it change between different j126 modules
Fan speed is output as 50% duty cycle with 1/20th the frequency of actual fan speed
Eg fan speed of 3000, frequency of 150 on feedback wire to j255. But some might be monitoring current aswel.

Regards Johnny
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Re: Audi Q7 2007 4.2 TDi BTR Engine

Postby STC » Fri Aug 26, 2016 10:36 pm

Thanks for that Johnny, Having spent most of the day on that, taking a step forwards and two back I was about to hang my boots up and ask for a refund on my training courses :D

When you wrote
Fan speed is output as 50% duty cycle with 1/20th the frequency of actual fan speed
Eg fan speed of 3000, frequency of 150 on feedback wire to j255. But some might be monitoring current as well.


That triggered me to look again at this from SSP361.

Fresh air blower control unit J126
The fresh air blower control unit J126 controls the
blower speed in the deluxe automatic air conditioner
and the four-zone deluxe automatic air conditioner.
In the manual system, a series resistor is installed in
its place
.



My Car has Climate! Hence No Resistor.

The way I now see it is that the feedback I am looking at in my captures is feedback through a resistor attached to at one end to V2 Fan Exciter Ground PWM and other to end to Feedback wire to proportionately alter the voltage as fan speed increases creating a workable signal for Diagnosis - In a MANUAL SYSTEM Which this is not. Nothing else makes sense? I have a Digital Freeview TV getting Analogue signals ?
It has to be a resister to give that that varied voltage and feedback, not Electronics.

I could Curse now and could get really mad, except it will not help.

Johnny thanks for the reply and info.
I will get back to you with he info you asked for.
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Re: Audi Q7 2007 4.2 TDi BTR Engine

Postby STC » Mon Aug 29, 2016 8:54 pm

I looked at this again today and took some photos of the measured blocks, which have disappeared.
In Block 2 (1) I did see 26 and also 3 & 6 - I looked them up on VAS to get the meanings. 26 directly blaming the fan.

The basic settings didnt make any difference either.

I cant remember the other blocks you asked for but can get them.

Saturday morning I did ring the dealer to confirm the part numbers and they are correct, and confirmed they have supplied them to the garage for that car.
A bit more digging and I can see that J255 can see V2 Fan speed, throwing another spanner in the works - Is that just a bad or Sneaky Fault ?
When I went through Guided the one thing thatstuck out was Fan Voltage. It read
Specified 0v
Actual 12.3v
At the time I thought that was the wrong way round and started chasing Control Units, and Wiring - truth being just my tail I think :(
Having tested the Blower fan to death, which works, I needed to look further afield.
In the Diagnostic Gateway I have DTC's for No Communication with J644 Energy Management and also G1 Alternator.

Next Step, Passenger Seat & Base out to get at J644. Scoped the Power supplies and Can Lines which are good. the blue wire to the alternator has a PWM signal on it with the engine running.
Just as I start getting a twitch towards a fix he produces an Invoice showng me that they have replaced that and fitted a new battery too - Genuine parts !! Yes they are Shiny and new !! :( :( In that moment of depression I forgot to save the Scope Trace. Easy enough to go and get.

I can Communicate with J255 which is on the same network as J644 so I can't really point the finger at the Gateway.

Defeated !!



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Re: Audi Q7 2007 4.2 TDi BTR Engine

Postby STC » Tue Aug 30, 2016 9:41 pm

Hi Johnny.

Here the Info you asked for:
VAG No 4L0 910 043 D. Component: KLIMA 4 ZONEN H15 0070
Soft Coding: Long Coding

MVB
002.....5.....3.....0.....0 then after some time
002....26.....3.....0.....0

045....0.0.....6.70...46%.....0%

046...7.75a....na.....na......na


Having exhausted myself of ideas of how many ways I can test a DC motor (with fins on it) I have now targeted the No Comms issue with J644. Today I stripped down and de pinned everything on that network at the CAN seperating connectors, both sides (T46a & T46b) except J644. Still no comms.

I believe that I have a bad J533 and /or J644 just no evidence to condemn either.

On top of that I have an alternator that does charge regardless of J644 Connected or not. Elsa shows just one blue wire from J644 and the big thick one at B+. How is it charging without an Excitor Voltage. That wire is dead until the engine starts and then I see a PWM.
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Re: Audi Q7 2007 4.2 TDi BTR Engine

Postby dieseljohnny » Thu Sep 01, 2016 12:58 pm

Can you pm me the vin and the part numbers of installed components?


t Different versions for vehicles with and without auxiliary/supplementary heater → Electronic parts catalogue

t From 11.2007 onwards, a modified fresh air blower control unit -J126-, a modified front operating and display unit (Climatronic control unit -J255-, “deluxe” version) and a modified fresh air blower -V2- will gradually be introduced on vehicles with a “deluxe” air conditioner. Make sure these components are correctly allocated to each other → Electronic parts catalogue.



t Up to 11.2007, vehicles with air conditioning systems ("basic" and "deluxe") are always fitted with a fresh air blower control unit -J126--D- with part number “7L0 907 521”, a fresh air blower -V2- with part number “7L0 820 021” (with different indices respectively) and a front operating and display unit Climatronic control unit -J255- with part number “4L0 820 043” up to index “J” → Electronic parts catalogue.
A87-10189


t From 11.2007 onwards, vehicles with a “deluxe” air conditioning system are gradually fitted with a fresh air blower control unit -J126--D- with part number “3C0 907 521” from index “B” onwards, a fresh air blower -V2- with part number “4LX 820 021” (with different indices respectively) and a front operating and display unit Climatronic control unit -J255- with part number “4L0 820 043” from index “K” onwards; there are no modifications for vehicles with “basic” air conditioning systems → Electronic parts catalogue. When renewing any of the components, make sure they are correctly allocated.

t The fresh air blower control unit -J126- with part number “3C0 907 521” from index “B” onwards relays the “positive” signal through from contact “4” of connector -C- to contact “1” of connector -B- when the ignition is switched on and the fresh air blower -V2- is actuated. The speed of the fresh air blower -V2- is regulated by the fresh air blower control unit -J126- via the earth connection between contact “2” of connector -B- and contact “3” of connector -C-

→ Current flow diagrams, Electrical fault finding and Fitting locations and → Guided Fault Finding function of vehicle diagnostic, testing and information system VAS 5051.
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Re: Audi Q7 2007 4.2 TDi BTR Engine

Postby STC » Sun Sep 04, 2016 12:21 pm

Can you pm me the vin and the part numbers of installed components?


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