2001 VW T4 Transporter 2.5TDI Non-Start Issue

AKAvant

Veteran Member
Joined
Oct 12, 2010
Location
Europe
TDI
2004 Audi A4 Avant 1.9TDI Quattro, 2002 VW California, 1998 Jetta TDI (Sold 6/16), 1997 B4 Passat TDI, 1993 Eurovan Weekender 1Z m-TDI conversion (Sold 5/12), 1992 AHU powered B3 Syncro Wagon
I have a TDI Transporter with the 2.5TDI engine that is having a non start issue. In the beginning it was intermittent and a wire was connected from the battery directly to the fuel cutoff solenoid on the fuel pump to use when the van could not be started. In the last 6 months this direct connection from the battery to the N109 cutoff solenoid has had to be used constantly. A bad power drain has also started occurring where the battery will be dead after one night of sitting.
Today I measured the voltage on the original wire at the solenoid and at pin 120 from the ECU and both showed 3.88V. So it doesn't seem like there is a break in the wire.
I recently had pulled the codes which made me think that this wire from the ECU to the solenoid was shorting out.

Address 01: Engine Labels: 074-906-018-ACV.lbl
Part No: 074 906 018 AL
Component: 2,5l R5 EDC 0000SG 3321
Coding: 00002
Shop #: WSC 02743
VCID: 60C46351E0FE47210FB-4B00

2 Faults Found:
17946 - Fuel Shutoff Solenoid (N109)
P1538 - 35-10 - Open or Short to Ground - Intermittent
18039 - Accelerator Position Sensor (G79)
P1631 - 35-00 - Signal too High
Readiness: N/A

So it doesn't seem like there is a short?
The battery was run down and measured 11.7V at the time but this was still enough to get the solenoid to click with the directly connected wire.
So what could be causing the ECU to not be sending enough volts to the solenoid? Could this be something related to the 109 relay (Terminal 30 voltage supply) or perhaps something failing within the fuse box? I have tried 3 different 109 relays (2 new) with no change.
As always any input is appreciated and thanks again!
 

alphaseinor

TDI Innovator, Gone but Not Forgotten
Joined
Jul 30, 2006
Location
Denton, TX
TDI
'03 Jetta TDI 780,000 miles (totaled out), 01 Audi TT 225 Quattro 230,000 Miles (runs great!), 00 Cabreetle Beetle dash, ALH & MK4 harness Swap
I'd check the basics first,
fuel at injectors
maybe try advancing the pump a bit
 

AKAvant

Veteran Member
Joined
Oct 12, 2010
Location
Europe
TDI
2004 Audi A4 Avant 1.9TDI Quattro, 2002 VW California, 1998 Jetta TDI (Sold 6/16), 1997 B4 Passat TDI, 1993 Eurovan Weekender 1Z m-TDI conversion (Sold 5/12), 1992 AHU powered B3 Syncro Wagon
Van starts and runs fine with 12v directly wired to the fuel shutoff solenoid. Don't think pump timing is an issue?
 

AKAvant

Veteran Member
Joined
Oct 12, 2010
Location
Europe
TDI
2004 Audi A4 Avant 1.9TDI Quattro, 2002 VW California, 1998 Jetta TDI (Sold 6/16), 1997 B4 Passat TDI, 1993 Eurovan Weekender 1Z m-TDI conversion (Sold 5/12), 1992 AHU powered B3 Syncro Wagon
So today the battery was fully charged when I started checking voltage. I first checked the power feed from fuse box plug G1 pin 7 and it showed a full 12.8V being fed to the ECU. I then checked pin 120 from the ECU (fuel cutoff solenoid feed) and it still only showed 3.88V. What's going on here? Isn't this supposed to be at least 12V? Am I looking at a fault in the ECU?
 

AKAvant

Veteran Member
Joined
Oct 12, 2010
Location
Europe
TDI
2004 Audi A4 Avant 1.9TDI Quattro, 2002 VW California, 1998 Jetta TDI (Sold 6/16), 1997 B4 Passat TDI, 1993 Eurovan Weekender 1Z m-TDI conversion (Sold 5/12), 1992 AHU powered B3 Syncro Wagon
So I pulled out the ECU last night and brought it inside just to inspect it. Today after taking the earlier volt readings I reinstalled the ECU and the van started up on the first try without the battery to solenoid jumper wire connected. Voltage at the solenoid was now at 13.8v.
The glow plug light was now blinking so I shut off the van and scanned for codes.
These codes popped up:

Address 01: Engine Labels: 074-906-018-ACV.lbl
Part No: 074 906 018 AL
Component: 2,5l R5 EDC 0000SG 3321
Coding: 00002
Shop #: WSC 02743
VCID: 60C46351E0FE47210FB-4B00

5 Faults Found:
18039 - Accelerator Position Sensor (G79)
P1631 - 35-00 - Signal too High
18009 - Relay for Supply Voltage Terminal 30 (J317)
P1601 - 35-00 - Implausible Signal
17971 - Quantity Adjuster (N146)
P1563 - 35-00 - Lower Limit Reached
17762 - Modulating Piston Movement Sensor (G149)
P1354 - 35-00 - Electrical Malfunction
17655 - Needle Lift Sensor (G80)
P1247 - 35-00 - Open or Short to Plus
Readiness: N/A

Address 17: Instruments Labels: 7D0-920-xxx-17.lbl
Part No: 7D0 920 802 Q
Component: T4-KOMBIINSTR. VDO V01
Coding: 01111
Shop #: WSC 00089
VCID: 3162D615FB94BEA9D05-513C

1 Fault Found:
01314 - Engine Control Module
49-10 - No Communications - Intermittent

Address 19: CAN Gateway Labels: 6N0-909-901-19.lbl
Part No: 6N0 909 901
Component: Gateway K<->CAN 0001
Coding: 00000
Shop #: WSC 02743
VCID: 70E41311301EF7A19FB-513C

1 Fault Found:
01314 - Engine Control Module
49-10 - No Communications - Intermittent


I then started the van again with no problem and cleared the codes and they did not return.
What is going on? Potentially a loose connection at T10a on the engine since many items throwing codes meet at that junction? Or just multiple chafed wires that were grounding out but now aren't?
Could the immobilizer be causing any of this?
 
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