Does the A6 30V have a ECU relay?
#21
2.79V is not right....
If you are reading to a solid ground (use the negative battery terminal to be sure), you can ignore the 2.79V. There is really nothing in the car that runs on anything less than 12V until you get to sensor outputs and the like. If you're using a high impedance (digital) meter, you're reading what's known as "Phantom Voltage".
There's really no power there....that's why you are reading it everywhere. If you can get to the fuse terminals with the fuse still plugged in, read each fuse line side and load side to ground. Try with the key off, on and in the start position. Any that don't show the same voltage on the line and load side are blown. If it will start with starting fluid means the ignition is OK and you at least have a fuel problem. You need to figure out where the power to the fuel pump is being lost. Fuse, relay, etc. Audi wiring diagrams are a real beast to follow and if you're unfamiliar with schematics and wiring diagrams, you might want to get help from someone who's tech savvy. But mainly. you need to get power to the fuel pump, then if it starts, you can go from there. If you have fuel from the pump, then electronics controlling the injectors are the next step. I'm betting your fuel pump is not working. Resistance reading (Ohms) is really only useful when looking for bad grounds or blown fuses. Reading resistance on any electronics is dangerous because the meter applies voltage to the circuit and is not likely to show a problem anyway. Patience is what helps (and a can of beer doesn't hurt either). Good luck.
There's really no power there....that's why you are reading it everywhere. If you can get to the fuse terminals with the fuse still plugged in, read each fuse line side and load side to ground. Try with the key off, on and in the start position. Any that don't show the same voltage on the line and load side are blown. If it will start with starting fluid means the ignition is OK and you at least have a fuel problem. You need to figure out where the power to the fuel pump is being lost. Fuse, relay, etc. Audi wiring diagrams are a real beast to follow and if you're unfamiliar with schematics and wiring diagrams, you might want to get help from someone who's tech savvy. But mainly. you need to get power to the fuel pump, then if it starts, you can go from there. If you have fuel from the pump, then electronics controlling the injectors are the next step. I'm betting your fuel pump is not working. Resistance reading (Ohms) is really only useful when looking for bad grounds or blown fuses. Reading resistance on any electronics is dangerous because the meter applies voltage to the circuit and is not likely to show a problem anyway. Patience is what helps (and a can of beer doesn't hurt either). Good luck.
Last edited by meternerd; 09-25-2017 at 09:11 AM.
#22
The relay panel called a 3-fold relay panel is next to the ECM under the black plastic shroud, outboard of the brake booster, according to my Bentley's manual. Mine is a 2001 2.7T and that's where it is on mine. There's a screwed on black plastic cover with a (bulge) in one corner. But...there's a note saying different models and years have components in different locations. Why make it easy!
Last edited by meternerd; 09-25-2017 at 12:09 PM.
#23
I pulled the fuel line and turned it over and fuel came out. Was thinking it was injectors not opening so changed cam positioning sensor but nothing. Hooked up scanner and have no reply from computer.
#24
One comment.....after reading your post, I went and put red markers on the battery cover and the positive terminal of the battery in hopes of not making the same mistake. Doesn't help you, but it might clue the rest of us to connect it right, even when we're in a hurry, in the dark and late for work. Don't give up, and make sure you keep us all up to date on your progress.
Last edited by meternerd; 09-26-2017 at 02:58 PM.
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Eric P
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