E63 57 Report post Posted December 30, 2023 I'm trying to find a 12v and GND wire in my rear-vision mirror to hardwire a radar detector, but I can't seem to get the right wire. I've tried fiddling around with a multimeter, but I'm not certain how to find 12V and GND. I've loaded up the diagram in ISTA and I have no idea what I'm looking at. I was expecting it to give me a pin-out with the voltages of each pin listed. Is there somewhere else I should be looking? Is GND always brown? Has anyone done something similar in E60/E63/E64 and knows what wires to use? Might I need to strip the wire for my taps to contact? No laughing please, I'm a total dipshit when it comes to electrical (and most other automotive topics, really 😆) Here's a pic of the product I'm using: Quote Share this post Link to post Share on other sites
kwhelan 241 Report post Posted December 30, 2023 (edited) https://www.bimmerfest.com/threads/schematics-for-rear-view-mirrow.1459181/ no stripping for taps the pinouts are in there but your on the wrong page there, its not an easy thing to browse but its in there somewhere, if you find the module number of the plug you can search for it brown is definitely common for earth but not guaranteed ,put your mutlimeter in buzzer mode for loop testing i(t will make a noise when you touch leads together) and you can check the brown wire to a metal part of body or car, if ir makes a noise its connected, make sure you test between two metal parts of the car first to check your actually touching metal not paint, confirm you are touching a good earth for power set multimeter to dc volts probably something like 40v on the tool and look for a 12 v reading when the other lead is connected to the car body metal, test with key on and off , be aware alot of circuits don't go to sleep immediately when the key is off so make sure car has powered down and leave window open as opening the door will wake up some circuits Edited December 30, 2023 by kwhelan Quote Share this post Link to post Share on other sites
E63 57 Report post Posted December 30, 2023 Thanks Kevin. I'm reading through this thread now. Quote if you find the module number of the plug you can search for it Searching isn't giving me much. I've searched for X18246, and 616035. Nothing gives me a pinout. Quote no stripping for taps Cheers for confirming this. Quote put your mutlimeter in buzzer mode for loop testing I don't know if my multimeter has buzzer mode, I've got this cheapo one here: Medalist | Digital Multimeter 150x70mm Orange | Mitre10 Quote be aware alot of circuits don't go to sleep immediately when the key is off so make sure car has powered down and leave window open as opening the door will wake up some circuits My understanding is that the accessory circuits stay on for 8 minutes after ignition off. Quote Share this post Link to post Share on other sites
E63 57 Report post Posted December 30, 2023 I didn't have any luck with the multimeter so far. I couldn't find anywhere to ground. I'm scared to use the cigarette lighter again because last time the probe slipped and I needed a new fuse 😂 I found this image, which is helping to make sense of what I'm seeing on ISTA: Seem right? Gonna go fiddle and see if this does the trick. Quote Share this post Link to post Share on other sites
E63 57 Report post Posted December 30, 2023 The signal codes were gleaned from the forum post @kwhelan linked. Quote Share this post Link to post Share on other sites
Eagle 1661 Report post Posted December 30, 2023 Looks ok . Never seen a BMW where brown wasn't ground. You'd need to insert a pin etc first into the back on the mirror connector to find 12V because normal multimeter leads are too big. You can always put a terminal on the ground wire and use an existing screw\bolt around the area to ground it to the roof\body, i think that was i did with mine to avoid to avoid using another tap, Quote Share this post Link to post Share on other sites
E63 57 Report post Posted December 30, 2023 Quote You'd need to insert a pin etc first into the back Yeah, noticed this. I reckon some test lead adapters would be quite handy. I've used staples before, and they don't really stay in place. No luck with green/yellow, somehow... Tried in accessory mode, ignition on, the lot. FWIW, I've verified that the detector powers up when connected straight into a 12v battery. Does it matter which side of the plug I use? I'm tapping into the back of the car-side of the plug, as opposed to the back of the connector on the mirror-side. Mirror-side is really difficult to access. Quote Share this post Link to post Share on other sites
Eagle 1661 Report post Posted December 31, 2023 Ive never used those style leads, only wire or fuse tap, they dont look secure to me but if you sure the pins are making good contact then you probably need to probe the wires and verify 12V with the meter. Is that wiring diagram accurate? If you do have power on the green\yellow then its probably not making a good ground connection so id go for the above or wire tap. Not sure what are you saying about the plug. You can only really tap into the back of the harness connector (carside) with what you are using Quote Share this post Link to post Share on other sites
E63 57 Report post Posted December 31, 2023 The pin broke off the positive, so I'm a bit stuck now :))) I'll fix it, and try grounding it to a bolt with an eyelet terminal. I think I need to buy a kids' electrical starter kit so I can learn how to process electricity in my mind. Quote Share this post Link to post Share on other sites
Eagle 1661 Report post Posted December 31, 2023 If the wiring colours match up with the diagram then its probably accurate. If you insert a pin, paper clip etc into the back of the green\yellow connector so it touching the metal (the one that connects directly to the mirror, under plastic trim?) You should read +12V with the multimeter set on 20 position with the red lead on the pin yellow\green wire and black lead grounded to bare metal (screw\bolt on body\roof) I think its a connection issue with your pins but i you'd need to post photos of what you are talking about regarding the connectors above as im not familiar with E63 wiring or what you trying to do exactly. Id just install one of these - https://www.jaycar.co.nz/double-standard-blade-fuse-socket-wire-tap/p/SF5115?pos=3&queryId=2eea1039fdd6f7f968f4337ac7e42a5f&sort=relevance&searchText=Fuse Socket Wire Tap Running a wire from fuse box, up pillar trim isnt that hard and you shouldnt have to take off much besides pillar trim, maybe the glove box then at least you got a perfect connection with a separate circuit These work well but never seen them in NZ Quote Share this post Link to post Share on other sites
kwhelan 241 Report post Posted December 31, 2023 (edited) think your making hard work of your meter to be honest, make sure you get 12v across your battery to confirm you even have the meter on the right setting first, probably says 40v or something similar, needs to be over 12v for sure all meters have a loop test circuit, you won't do any damage if you change the dial, hold leads together and fiddle until you find it as I can't quite see from pic make sure you understand the pin numbering is being reversed because your looking at the back of the plug, playing with something like a staple in the back of a plug is asking for fuse blows, just too small and fiddly try stripping a piece of wire or maybe a paperclip wrap it around the red probe 3 or 4 times tight with a 20mm extension so its tight/firm on the red probe then you have a smaller point to insert into plug and use black probe to earth somewhere near on the roof so the two leads arn't side by side and can touch and blow the fuse by mistake confirm your earth lead is actually earthed by checking for a loop between two metal points on car, door hinges are usually good points for earth one of those wires in the mirror plug has 12 volts so if you can't find it your not connecting correctly lastly I would have thought if you have used lighter circuit before you already know those wires so no lead required BTW pack of 100 assorted fuses is like $5 ON AliExpress , always have a pack handy Edited January 1 by kwhelan Quote Share this post Link to post Share on other sites
E63 57 Report post Posted January 2 The meter was looking good, had some 12v reads that made me feel like I was on the right track. I'll go over to Jaycar when I can and grab a few bits to have another go at this. I know it shouldn't be this complicated. Quote make sure you understand the pin numbering is being reversed because your looking at the back of the plug, Thankfully the plug is asymmetrical, and included on diagrams, so it's quite easy to know you're heading in the right direction. Quote Running a wire from fuse box, up pillar trim isnt that hard and you shouldnt have to take off much besides pillar trim, maybe the glove box then at least you got a perfect connection with a separate circuit In a way this seems way easier, but I hate how much extra wire it takes to go this route, when I should be able to get the mirror taps working. Maybe some smaller taps that I can get a bit further into the plug would help. Thanks for your help guys. I'll get to the bottom of this. Quote Share this post Link to post Share on other sites
aja540i 1906 Report post Posted January 2 Probably easier to find a constant 12v source in the interior light and not far to run a piece of wire if you need to? Quote Share this post Link to post Share on other sites
E63 57 Report post Posted January 3 I got a couple of bits from Jaycar and I’ll have another run at this in the weekend. Quote Share this post Link to post Share on other sites