ECU failure

Shenandoah

Veteran Member
Joined
Jan 9, 2008
Location
Shenandoah Valley, VA
TDI
2005 Jetta Wagon; 2005 Beetle; 2004 Jetta; 2002 Golf (three of them); 2002 Jetta Wagon; 2000 Audi TT->TDI; 1999 Beetle
Folks,

I've been working on the 2002 Jetta sedan (2.0l gas, 01m automatic transmission, 192k miles) my daughter drives. I replaced the solenoids and ribbon cable/harness. I had several solenoids out of range and when I checked the ribbon cable, it had wore through where one of the clips holds it in place. Drove the car about 200 miles over the course of the week without any issues.

A couple days later I was driving up to the grocery store and the car just quit running. It would turn over, but wouldn't start. I had it towed home and when I tried to scan the engine for codes, I got a message "no response from controller". VCDS couldn't connect to the ECU. I checked all the fuses and replaced the fuel pump relay. Still couldn't scan the ECU. I checked and cleaned the grounds, still no ECU. I took the ECU from one of my "parts" cars and put that in to see if it would recognize it and sure enough it did.

I bought a used ECU, same part number, off of ebay. I put it in and the car started and ran for a couple seconds before the immobilizer cut it off. I'm sending the ECU off for an immobilizer delete.

I know ECU failures are rare. I'm wondering if something "fried" the original ECU. Anything I should look for before the replacement ECU comes back? Thanks.

Eric
 

Mozambiquer

Vendor , w/Business number
Joined
Mar 21, 2015
Location
Versailles Missouri
TDI
1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI, 2005 VW Passat wagon TDI X3, 2001 VW golf TDI, 1980 VW rabbit pickup,
Did you check the relay 109? No communication is probably not the ECU being bad, but more likely wiring. Edit: I just saw that it's a gasser... I know very little on that one, though I've fought with a similar one. It was a 2002 Jetta wagon 2.0 auto, and it acted like the immobilizer was tripping. I paired it, programmed the keys etc, still nothing. Finally realized that the VIN number in the ecm didn't match, someone had replaced the ECM with one from a 2003 which is immo3 whereas my car was an immo2 car. Deleted the immobilizer and it was all good again.
Folks,

I've been working on the 2002 Jetta sedan (2.0l gas, 01m automatic transmission, 192k miles) my daughter drives. I replaced the solenoids and ribbon cable/harness. I had several solenoids out of range and when I checked the ribbon cable, it had wore through where one of the clips holds it in place. Drove the car about 200 miles over the course of the week without any issues.

A couple days later I was driving up to the grocery store and the car just quit running. It would turn over, but wouldn't start. I had it towed home and when I tried to scan the engine for codes, I got a message "no response from controller". VCDS couldn't connect to the ECU. I checked all the fuses and replaced the fuel pump relay. Still couldn't scan the ECU. I checked and cleaned the grounds, still no ECU. I took the ECU from one of my "parts" cars and put that in to see if it would recognize it and sure enough it did.

I bought a used ECU, same part number, off of ebay. I put it in and the car started and ran for a couple seconds before the immobilizer cut it off. I'm sending the ECU off for an immobilizer delete.

I know ECU failures are rare. I'm wondering if something "fried" the original ECU. Anything I should look for before the replacement ECU comes back? Thanks.

Eric
 

Shenandoah

Veteran Member
Joined
Jan 9, 2008
Location
Shenandoah Valley, VA
TDI
2005 Jetta Wagon; 2005 Beetle; 2004 Jetta; 2002 Golf (three of them); 2002 Jetta Wagon; 2000 Audi TT->TDI; 1999 Beetle
Mozambiquer,

With the gas 2.0l the fuel pump relay is the equivalent of the 109 relay for the TDI. Yes, I swapped out the relay from one of my parts cars. Still no communication with the ECU. I swapped in an ECU from a gas 1.8l turbo and could see that ECU with VCDS, leading me to believe the original ECU failed. When I put the original ECU back in, VCDS could not see/scan it.

Eric
 
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