06 Jetta - Disconnected battery, now VCDS can't find ECU

Pabluski

Member
Joined
Aug 23, 2016
Location
China Grove, NC
TDI
Black 2009 Jetta, Silver 2009 Jetta, White 2004 JSW, White 2006 Jetta
[Solved] 06 Jetta - Disconnected battery, now VCDS can't find ECU

Hello folks.
My 06 Jetta TDI has been having problems with discharging the battery overnight. I was thinking it was the battery going bad so I charged it, then pulled it out and took it to AutoZone. They told me that the battery was ok. I put it back in the car. Now when I turn the ignition on, I am getting the flashing PRNDS and the car won't start.
I cleaned up the ground connections and tried again - no change.
I can scan all of the modules in the car with VCDS, except the engine. Some of the modules complain of missing ECU communication.
I am leaning towards a bad ECU.
I am trying to pull the ECU to re-seat the connector and try again.
What else should I do?
What will it take to replace the ECU?
Thanks.
 
Last edited:

Ol'Rattler

Top Post Dawg
Joined
Jul 3, 2007
Location
PNA
TDI
2006 BRM Jetta
Pretty far fetched, but people have done it. Is it possible you got the battery connections reversed.
 

Pabluski

Member
Joined
Aug 23, 2016
Location
China Grove, NC
TDI
Black 2009 Jetta, Silver 2009 Jetta, White 2004 JSW, White 2006 Jetta
Thanks for responding...that did not happen in this case.

- I have checked all of the fuses - none are blown.
- I have disconnected and re-seated the ECU connectors

I am considering buying an ECU at the junk yard to see if it is the wiring or the ECU. Is there an easier way to test this?
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Are the communication DTCs in the other modules for the Engine? It sure sounds to me like a bad Engine controller.

Check the big wires on the car side connector for power and ground. A used ECU will not let your engine start, however it will allow communication and that would at least verify if that is indeed the issue. If so, you can have the immo deleted on that replacement one.
 

compu_85

Gadget Guy
Joined
Sep 29, 2003
Location
La Conner, WA
TDI
... None :S
Start with a full VCDS auto scan. That will tell you which modules are working, and which are not.

If the CAN gateway fails, for instance, you can't get to the ECU with VCDS since the diagnostic traffic goes through the gateway.

-J
 

Henrick

Top Post Dawg
Joined
Aug 24, 2010
Location
Ireland
TDI
Golf VI TDI, 77 kW (CAYC)
Do you get any dash lights when you turn on the ignition? E.g. check engine light, glow plug light?
Worth to check the main relay (460 IIRC, there are two of them, one for wipers/washing system, another for ECU, swap them and give it another try) before pulling the ECU.
 

crazyrunner33

Veteran Member
Joined
Jul 11, 2006
Location
NC
TDI
'10 Golf(bought back)
I agree with Henrick's suggestion, the 460 is a very good place to start with issues like this. There's an example of a similar issue that ended up being the 460:

http://forums.tdiclub.com/showthread.php?t=454597

Let me know if you need a hand, or someone to supervise with terrible dad jokes, I'm 20 minutes down the road from you.
 

Pabluski

Member
Joined
Aug 23, 2016
Location
China Grove, NC
TDI
Black 2009 Jetta, Silver 2009 Jetta, White 2004 JSW, White 2006 Jetta
Solved!

First of all, thank you all for helping me.

I got a junk yard ECU just to see if it would scan - it did not. So, I surmised that I had a wiring issue. I checked the ground points in the engine compartment and cleaned them up, but no joy in vdubville. I started to trace all the power going to the ECU. When I put my voltmeter probe on the SB10 fuse it made a spark sound! When I wiggle it a bit, it does it again. I pulled it, polished it up and slightly bent the spades in an attempt to get a better physical connection. No more PRNDS! Car starts!

Hurray. I had prayed for wisdom today since this issue was baffling me.
 

kbaisley

Veteran Member
Joined
Jul 31, 2002
Location
Midwest
TDI
2006 Jetta TDI 5spd
Nice find.. glad it worked out. Thanks for the follow up to the thread, this could save someone a bit of time.
 
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