GZ

I just noticed that it is terminated and connected to the relay box... Strange...


Have you checked what it feeds power to yet?

MrJingle

had trouble tracing it further than the relay box because of stuff in the way, but checked out the trunk, never opened the floor past the spare tire until now. Certainly used to be amps/subs in there. 5 exposed wires. One goes to the speakers on the passenger side through the trunk wall. The big one on the left is just cut and glued down, middle red same, right brown one is attached to the metal there? Then one small blue one loose as well.

None of this matters to me right now at all, speakers work just fine, I'm just worried all this unfinished craziness could be related to my possible electrical starting/cutting issues

GZ

I would disconnect the power lead from the relay box, if it is indeed connected there. Also check the wiring around the relay box. The potential for heavy current draw is high with aftermarket amplifiers and the stock wiring is not meant for that much current and there could be heat damaged leads in that vicinity. Most high power aftermarket amplifiers are connected directly to the battery.


Not to mention that with the lead attached to power there is a huge chance for a short circuit...


I would trace the second wire and see where it is connected. As for the dark one on the right... That would just be the amps ground to chassis. It will pose no issue as it is.


The blue one is the switch lead. It probably runs under the dashboard to behind where the radio is mounted. Also a non issue if disconnected.

MrJingle

thanks gz, very helpful stuff.

I will try to take out the big lead on the relay box, and hopefully trace/remove it to the battery, and from there to the trunk. Dumb question, but I'm assuming always smart to unhook the battery when messing with the relays (ecu will reset)? Also short of a giant smolder or melted metal, will there be any signs if this has been the cause of shorts? i did have some ecu/ground codes earlier.

16795/P0411: Secondary Air Injection System: Incorrect Flow Detected
17925/P1517: Power Supply Relay for ECU (J271 or J363): Electrical Malfunction
16684/P0300: Random/Multiple Cylinder Misfire Detected
16686/P0302: Cylinder 2 Misfire Detected
18014/P1606: Rough Road/Engine Torque Signal from ABS: Electrical Malfunction
16688/P0304: Cylinder 4 Misfire Detected

GZ

I am not completely familiar with the fault codes and possible causes for these vehicles...


When inspecting the relay box for overheated wire, you are looking for discolored and/or brittle insulation.


I don't know what possessed the installer to connect such a current heavy device to the relay box.


Just an FYI... I am in no way saying that this is the cause or is even related to your current electrical issues... But they could have and can compound the situation.

MrJingle

Who knows why, either it was something small enough it didn't matter, or it caused an issue back then so they did rip it out.

That's my thought process too, it could be irrelevant, be a piece of the problem, or be an eventual problem, either way I want it all gone.

thanks again

MrJingle

So the new ecu relay is in, everything in there looks ok, and works after replacing, but time will tell if that was an issue. I was trying to do the crank sensor myself, but I'm not even sure which one im looking for, can't tell from the diy, might just bring it to a shop, but I don't trust them with audis here anymore than I trust myself. Here is what im looking at

hing

That is an aftermarket power supply cable, and in line fuse... Probably to run an aftermarket amplifier. If you trace it, it should connect directly to the battery's positive terminal and then run into the trunk area.

honkong

I've never messed with my speakers so no idea

MrJingle

update, replaced the ecu relay, things worked perfect for a month or so, could never get the problem to reoccur. Decided better to leave the audio wires alone. Yesterday after a drive I started it back up (hooot, 95+ here for days if that matters), and the cel was blinking, shaky, super limp mode, got it home about a mile away, pulled codes 16884,16885. this morning fine, but again after i started it after using it a little that day, same thing, same codes, same limp mode.

internet says coils, possibly the speed sensor, or leak in a tube somewhere. Any advice on where to poke around for leaks ? Also, is there a way to see the catalytic converter by popping the hood?

also im looking at these VEMO coils on Audi B5 A4 Quattro 1.8T Engine Ignition Coil ATW Engine Code - ECS Tuning they are quite cheap, anyone used them without blowing anything up?