Ignition coils not firing?

Tiny
JOSHMODE2
  • MEMBER
  • 2004 VOLKSWAGEN PASSAT
  • 1.8L
  • 4 CYL
  • TURBO
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
My ignition coils are not firing because P0685 it will crank but will not start and I checked the ignition coils and they're not firing I found that the fuel pump relay was bad so I changed it thinking that was it and it still won't start I changed all the fuses now all I have left is a relays but I have no manual showing what relays go where and what relays or what because I lost my owner's manual and I don't have the money to afford Haynes manual.
Tuesday, August 5th, 2025 AT 3:55 PM

5 Replies

Tiny
STEVE W.
  • MECHANIC
  • 15,233 POSTS
How about we do a bit of testing first? Grab a cheap test light and find fuse 29 in the panel on the left side of the dash. Turn on the key and probe the two tabs on the back of that fuse. There should be power there. If there isn't then the next stop is the fuel pump relay, pull it and look for power on terminal 17 That should have power full time. If you have power, there then find the power supply relay in the box next to the ECM. Pull it and check for power on terminals 2 and 9. If you have power there then put the relays back in. Then go to the ECM itself. Look for power on terminal 62. If you have power, there but still nothing the ECM might be the issue because that is the power to the ECM.
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Tuesday, August 5th, 2025 AT 7:45 PM
Tiny
JOSHMODE2
  • MEMBER
  • 14 POSTS
Thank you, I will try that and let you know.
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Wednesday, August 6th, 2025 AT 6:54 AM
Tiny
STEVE W.
  • MECHANIC
  • 15,233 POSTS
We will be waiting.
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Wednesday, August 6th, 2025 AT 11:25 AM
Tiny
JOSHMODE2
  • MEMBER
  • 14 POSTS
  • 2004 VOLKSWAGEN PASSAT
  • 1.8L
  • 4 CYL
  • TURBO
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
I need help cuz my ignition coils are not firing and I don't know why and I can't figure it out I replaced all the fuses I see relays but I don't have owners manual to tell me which ones are which so I can't check them I don't know how to check it in please help me thank you
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Wednesday, August 6th, 2025 AT 2:05 PM (Merged)
Tiny
STEVE W.
  • MECHANIC
  • 15,233 POSTS
REF - https://www.2carpros.com/questions/ignition-coils-not-fine
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Wednesday, August 6th, 2025 AT 2:06 PM (Merged)

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