A6 3.0 multiple codes
First time poster here, looking for some advice/guidance. I have a 2002 A6 3.0 Quattro 120k. Car has multiple codes and I'm having trouble gettin to the botto of the problem.
First off, please ignore o2 codes, I had them unplugged for this scan for diagnostic purposes. If I clear all codes and rescan with the key in the acc position (not running) none of these codes should come up until the car is running again. That is not the case tho, the brake booster sensor code comes up as soon as I erase the codes. I recently got a Bentley for the car, the cd digital copy. I am having issues opening the program, so as of now, until my brother in law does what he has to to make it work on Windows 7, I am without wiring diagrams. I did receive a piece of the booster sensor diagram, but not enough to do a full evaluation. If anyone can point me in the right direction with that circuit, I would very much appreciate it. Thanks in advance for any help you guys could offer, really need to get this old girl back on the road for work. Car is all original, no mods. New battery, tb cleaned, all new vacuum lines and hoses, new pcv, all grounds I could find cleaned, all fuses are operational with none missing. Code:
Saturday,25,March,2017,23:04:31:47582 |
Forgot to mention, the booster sensor code even pops up when the plug is removed from the sensor without the car running. This has me baffled
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I'll defer to those more expert in engine controls here, but I'm thinking an unplugged connector or wiring harness damage. It's possible the engine controller reads a sensor as shorted to positive or ground when it can't see it at all. If you get the Bentley working, I think there are tests to look for voltage at some of the sensor connectors that are easy to access. I'd start there, and then trace back toward the controller. Please let us know what you find.
BTW, I've run the Bentley manual fine under Windows 7 XP Mode/XP Virtual Machine. Unfortunately, Microsoft dropped that for Win 10. You can run it under Hyper-V (or other 3rd party software, apparently) but officially you need an XP license, and it doesn't work as well as in Win 7. The info's fine, just the display and smoothness aren't as good on my machine. I'm keeping one old laptop on Win7 just for this sort of thing. |
Can't find an edit option for my post for some reason. The maf blocks are reading 0 in vcds as well, but I unplug the maf the car stumbles on its face until I plug the connector back in.
I'm clueless when it comes to that kind of work with computers, that's why my brother in law is messing with that Bentley cd. If I would have known about this nonsense, I would have sourced a paperback copy instead. |
"18320 - Pressure Sensor for Brake Boost (G294)
P1912 - 001 - Short to Plus" That is sort of explaining the issue. First, with sensor disconnected, clear all codes. See if the code comes back. If it does, it is your wiring or control module. If no code, then it is most likely your sensor. For more troubleshooting: Ignition key turned off completely, disconnect sensor and check for continuity with voltmeter between contacts. If it is, sensor is either shorted or may open under vacuum. Next, repeat the same check with the wiring connector pins. If continuity exists, there might be a short somewhere in wiring. Next, turn the car on and, check voltages on the contacts with ground (battery "-" or body ground). Finally, you may have to trace the wires and test continuity for each contact at where they are terminating. |
Yes, with sensor disconnected, the code comes back. I can really use some help with the wiring schematics for the complete brake booster pressure sensor circuit. I have a feeling it's going to be a few days before I get my laptop back with the Bentley working on it, and I need to get this car going asap.
Thank for the replies so far |
1 Attachment(s)
Originally Posted by Prplhz96
(Post 24943656)
Yes, with sensor disconnected, the code comes back. I can really use some help with the wiring schematics for the complete brake booster pressure sensor circuit. I have a feeling it's going to be a few days before I get my laptop back with the Bentley working on it, and I need to get this car going asap.
Thank for the replies so far |
Originally Posted by georgeb944
(Post 24943689)
Here ya go!
Thanks!! I sent you a pm |
Ugh, this post is killin me with not being able to edit. If anyone has the schematic for the G294 booster pressure sensor compete circuit, it'll help a ton. I believe it will have the cam sensors on it as well, maybe not tho. The one George posted doesn't have it in there.
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1 Attachment(s)
Originally Posted by Prplhz96
(Post 24943736)
Ugh, this post is killin me with not being able to edit. If anyone has the schematic for the G294 booster pressure sensor compete circuit, it'll help a ton. I believe it will have the cam sensors on it as well, maybe not tho. The one George posted doesn't have it in there.
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