Car won’t start - relay 100 issue

[daveaustin]

Vw EOS 2007 TDI
Car had been driven with air con on and then parked. On returning short time after to car it’s fans were on continuous and therefore battery dead and car wouldn’t start. Unable to jump start car with recovery,
New battery fitted and still wouldn’t start, it would turn over but no start.
Diagnostic found various codes caused by flat battery, including 01314 code.
The relay 100 was removed and a link put between two connections and the car will start first time.
No codes are found once car runs.
All fuses have been checked.
Relay 100 is working, replacement relay fitted and still won’t start unless temp linked on connections.
Is there another relay fuse location that may cause this issue.
Don’t want to strip and replace ECU if something simple.

[Crasher]

Engine code or VIN?

[daveaustin]

engine code or vin?

wvwzzz1fz8v025099

[Crasher]

2008 model with the EU4 BMM DPF engine. The central electrics unit only has one relay at position A1, the other position, A2, has a jumper. The relay is known as "J317 Relay for voltage supply of terminal 30" and this provides power to fuses 13, 14, 15, 21, 22, 23 and 24. The relay is fed directly from the battery unfused at pin 30 and its output to the fuses is from pin 87, the matching board points are what you have been bridging? The relays earth command comes from the engine ECU via a tiny black/grey wire to the relays terminal 86 and its constant live power is from fuse 10. A new 100 relay is now part number 4H0 951 253 and has the number 644 printed on top. An interesting anomaly is that ETKA the VAG parts system says that position A2 should have a 458 relay but that's wrong according to the ELSA wiring diagram.

[mickeybo]

What your actually doing your bridgeing out 30 & 87 terminals & car starts when you do this what your by passing your ignition & your earth is missing

[Crasher]

What your actually doing your bridgeing out 30 & 87 terminals & car starts when you do this what your by passing your ignition & your earth is missing

The relays power could be missing but more likely the earth trigger from the ECU is the problem, I have seen the wire snap under the fuse box.