New Beetle 2003 ECU No communication. All other modules OK

   #21  
Jack@European_Parts

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LucaDN, as a side note, 12 volts does not sometimes mean anything, meaning when you have it make sure it can light up at least a tail light bulb, bet even Jack has had his ASS handed to him on that, and if not there is still time..

LARIMORE
Click to expand...


Oh no........ It has and I imagine it will again catch me every once and a while, an asshole ground or power source is fitting for an asshole like me........:p

Relay wouldn't click though if the case ...........well usually!

I believe terminal 15 power is indeed getting to ecu at T121/62 and the ECU is sending a pulse from T121/23 to relay at 86A via C circuit!
 
   #22  
LucaDN

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Jack@European_Parts said:
I believe terminal 15 power is indeed getting to ecu at T121/62 and the ECU is sending a pulse from T121/23 to relay at 86A via C circuit!
Click to expand...

That's easy to verify, I disconnected T121 (i.e. the ECU) and when I turn the ignition ON the relay is still clicking. So I guess it's driven by the ignition switch directly.
 
   #23  
Jack@European_Parts

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Check the function of the diode in relay by isolating the terminal pins of 86 and 86A............


WD27.3.png
Click to expand...
 
   #24  
LucaDN

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There is something I don't understand, though. As, clearly, the ECU is OFF even when T121 is connected to it (that's the point of the thread), I would expect that physically disconnecting it would change nothing at all. Instead, the ABS and Airbag lights on the instrument cluster are flashing when I turn the ignition on with the ECU disconnected. As a matter of fact, I did not play with the ignition while the ECU was disconnected because I did not want to trigger the Airbag (I am aware of being ignorant, so better stay safe).
Why is this happening if the ECU is not powered at all? Is the ECU acting as a 'passive' bridge for some wires?
 
   #25  
Jack@European_Parts

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There is something I don't understand, though. As, clearly, the ECU is OFF even when T121 is connected to it (that's the point of the thread), I would expect that physically disconnecting it would change nothing at all. Instead, the ABS and Airbag lights on the instrument cluster are flashing when I turn the ignition on with the ECU disconnected. As a matter of fact, I did not play with the ignition while the ECU was disconnected because I did not want to trigger the Airbag (I am aware of being ignorant, so better stay safe).
Why is this happening if the ECU is not powered at all? Is the ECU acting as a 'passive' bridge for some wires?
Click to expand...

Like I said it is I believe powering up .............just not completely and the K line might also be an issue as Jef mentioned due to the W- CAN High/Low to cluster being a big FUBAR!

Very common failure in beetle clusters..........

With T120 unplugged and ignition switch ON is power delivered via D51 at T121/62 when relay clicks ON?
 
   #26  
LucaDN

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Jack@European_Parts said:
Like I said it is I believe powering up .............just not completely and the K line might also be an issue as Jef mentioned due to the W- CAN High/Low to cluster being a big FUBAR!

Very common failure in beetle clusters..........

With T120 unplugged and ignition switch ON is power delivered via D51 at T121/62 when relay clicks ON?
Click to expand...

I will check everything mentioned in the latest posts tomorrow.
T120 is a typo, am I right?

Thanks for all the help
 
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LucaDN

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Good call on T121/62 I didn't notice it in the diagram. I bet it's powered :thanks:
 
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Jack@European_Parts

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I will check everything mentioned in the latest posts tomorrow.
T120 is a typo, am I right?

Thanks for all the help
Click to expand...

Indeed I fucked that up yes a typo...........see Larrymore!


Good call on T121/62 I didn't notice it in the diagram. I bet it's powered :thanks:
Click to expand...

Yup!
 
   #29  
LucaDN

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Jack@European_Parts said:
I believe terminal 15 power is indeed getting to ecu at T121/62 and the ECU is sending a pulse from T121/23 to relay at 86A via C circuit!
Click to expand...

LucaDN said:
That's easy to verify, I disconnected T121 (i.e. the ECU) and when I turn the ignition ON the relay is still clicking. So I guess it's driven by the ignition switch directly.
Click to expand...

I was reviewing the info and the diagram to be prepared for tomorrow. I did not realize that, but Jack you are absolutely right, the relay is connected to T121/23. But then, unless the diagram is wrong, how could J363 click with the ECU disconnected???

I'll let you know what I find out tomorrow, but I am going to bed worried now ...
 
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Jack@European_Parts

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I was reviewing the info and the diagram to be prepared for tomorrow. I did not realize that, but Jack you are absolutely right, the relay is connected to T121/23. But then, unless the diagram is wrong, how could J363 click with the ECUdisconnected???

I'll let you know what I find out tomorrow, but I am going to bed worried now ...
Click to expand...

If the J363 relay has a bad diode it could.............or harness corrosion bridge/backfeed!
 
   #31  
LucaDN

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Jack@European_Parts said:
If the J363 relay has a bad diode it could.............or harness corrosion bridge/backfeed!
Click to expand...

Thank you Jack, I was beginning to think I checked the wrong relay! Must be something like that
 
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Jack@European_Parts

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Thank you Jack, I was beginning to think I checked the wrong relay! Must be something like that
Click to expand...
Still.........I want to know the status of terminal 30 at the J363 from J59 X?
 
   #33  
LucaDN

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I will do that as well, no problem!
 
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1msfU.gif


-Uwe-
 
   #35  
LucaDN

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Hold your popcorn, I could not find the time to run all the tests today :D
I will complete them tomorrow morning.
I was able to test the T121 harness (ECU disconnected) and partially the J363 relay:

Simos3Harness_ECU_Disconnected.png


Readings on T121 harness – all pins have been probed.

  • With ignition OFF, ECU disconnected: 0V on all pins

  • With ignition ON, ECU disconnected: (0V if not listed)
PIN#VoltageConnection
3087 of J363 relay
912Speed signal from dash panel
1712K-Line
231286A of J363 relay
291.8T10/4 connector in plenum chamber (and then?)
392.7CAN-H
402.4CAN-L
6212Positive in engine compartment
6312Cruise / Brake pedal
6512Clutch pedal
8011491 (Fuel shut off)

J363 Relay seems OK. Coil 150 Ohm, Diode OK, Click test OK.
Continuity check for wire connecting Relay J363/87 to T121/3 is OK (which makes me think the relay is faulty after all, as I see 0V on the harness. We'll see)

I am puzzled, honestly. I need to think it over, but I'll do that after I complete all tests tomorrow.
 
   #36  
Jack@European_Parts

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Just remember the J59 terminal X relay feeds the J363 and provides that terminal 30 to terminal 87 & that you state is currently DEAD!............

Do you have power to terminal 30 at J363? ;)

giphy.gif



NostraJackASS Has Spoken!
 
   #37  
LucaDN

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I know, Jack, I know. I just couldn't get to do that!
 
   #39  
LucaDN

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Jack@European_Parts said:
Do you have power to terminal 30 at J363? ;)
Click to expand...

I checked right now. Ignition ON, no power at terminal 30.
But you knew that already, Jack, didn't you? :D
Sorry it took so long.

Now I need to find where the problem is, from terminal 30 to Fuse 10 (which I tested and has 12V).

Thanks thanks thanks, we are getting close :thanks::thanks:

P.S.
It doesn't help to be on a UK model, where some components are on the opposite side with respect to the factory manual. ECU is on the left, as usual, but Fuse box is on the right. Chasing down T6 connector (Pin4 connects terminal 30 to Fuse10) first thing.
 
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   #40  
LucaDN

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And before you yell at me, Jack .... :D
X contact, I know!!!!
 
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