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| 2000BEAST Regular Date registered: Jul 2010 Location: NOCAL USA Vehicle(s): 2003 G500 / 2008 Carrera S / 2019 GLC 43 Posts: 83  | Wiring near battery ? 2003 G500 ... 16 years ownership and now 160K miles. I changed the main battery today and noticed there were 3 wires (pictures) near the Negative (Ground) post that were disconnected. My first thought was they should plug into the Ground connector clamp on the battery, but didn't see any accomodations for them there. Looked around and I couldn't find any posts or connectors anywhere in the area that made sense to re-connect them. Didn't want to guess and screw something up, so I left them disconnected. . Started the truck, runs as it should except now there is a yellow ABS light on the dash (new- never seen that before). Anyone know what these 3 wires may be, where should they connect, and might they have anything to do with that new ABS light ? THX ! | ||
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| FrogWagen Member Date registered: Nov 2008 Location: Provence, France Vehicle(s): G300TD LWB Posts: 18 | Re: Wiring near battery ? Hi, I can’t see any pictures with your post, but:….. I own a G300TD LWB, so a slightly different machine, but similar era. I can't give you categoric answers to your situation, but I can give you what I hope will be a sensible view from someone who is an electrical/electronic engineer by training. I do all my own electrical work on my vehicle, but still have the MB main dealer do the services / major fix. My days of working under a car are over. Here's what might help you. 1. G-Wagens from some angles are over-engineered. Remember that fundamentally their roots are a military vehicle - so a belt & braces approach to design. 2. When it comes to the wiring and associated wiring harness, it's a massively complex affair. MB therefore want to reduce the number of combinations of that harness that they have to produce, install and offer spares for. (this keeps their cost down). The result is that the harness is built for 'redundancy'. i.e. MB offer multiple pre-orderable options when G-Wagens are purchased new. Some of the options can also be retro fitted. Over the years some options become 'standard' equipment. 3. In my experience the G-Wagen wiring harness has lots of spare wires with connectors attached that you come across when approaching some repair job or another. You’ll find these sprinkled all over the car. These are clearly there for the installation of some option or other that the original buyer did not order and hasn't been retro-fitted. These could even be for options in a similar G-Wagen model that uses the same wiring harness in manufacturing, but offers options your model doesn’t have available. 4. The last thing you should try to do without expert knowledge is try to connect these spare wires/connectors to anything! Certainly do not just assume these can be connect to ground/earth/chassis. At best you might just blow a fuse (or two) at worse, damage your wiring harness or damage some other electronic control unit buried elsewhere in the vehicle. My advice: “Leave very-well alone”. i.e. don’t dabble unless you are 100% sure you know what you’re doing. Your action of not connecting these was 100% the right course. When in comes to your ABS (Advance Breaking System) light. Again, I don’t have a categoric answer. However, I know from when I’ve disconnected my battery (and my car has much simpler electronic systems that yours) that various things may need a reset. The passenger central door-locking with key-fob is notorious at needing to be reset. Someone else may chime in hear and help you further, or you could check the forums for a topic like “ABS reset after battery swap” to see if there is a solution there. Resetting MB systems is generally easy, normally a combination of different button pushes. But given as this is a braking system warning it certainly deserves investigation & a fix finding. There is a good chance that the ABS light and your battery swap (cutting power to all electronics) may be related. But don't make the 'logical-problem-solving' error of assuming that this is the case. It could be circumstantual. i.e. perhaps you just happened to arrive at the point where something in the braking system genuinely does require attention (dont' know that this might be, brake-pads perhaps etc...) on the day you did a battery swap! Finally, I would be almost 100% sure that (if all you have done is battery swap & you didn’t touch any other wirning) there is no link between the ABS light and the three connectors you happened to come across. I'd suggest you treat the ABS warning light as a new problem & don't make the mistake of assuming just because you came across some spare wires that there's any link. Doing so will send you down a rabbit hole looking a fix that doesn't exist as it isn't related to the problem. Good luck. I hope some others with more specific domain knowledge can help you more. FrogWagen Edited by FrogWagen 11/26/2023 6:41 AM | ||
| #244065 - in reply to #244064 |
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| 2000BEAST Regular Date registered: Jul 2010 Location: NOCAL USA Vehicle(s): 2003 G500 / 2008 Carrera S / 2019 GLC 43 Posts: 83 | Re: Wiring near battery ? You are right on and all good advise. I'm with you - don't "guess" especially about wiring. Slowing down and going forward methodically when working on anything mechanical has always served me well. I drove the G around a bit but the Yellow ABS light did not go away. I then connected my Scan Tool and it came up with the one error code pertaining to ABS system. So I erased the code and the ABS warning light went away. I was expecting it to come back when I took a 60 mile drive this morning, but it did not. Happy now, and sort of typical with my experience with the G over these years. Pretty basic, somewhat simple (kinda) especially compared with the new version. I taped up those wires, and put them back in the battery box from where they came. Agree that these are likely for options that my truck did not come with. Alls well that ends well... thanks for the comments ! | ||
| #244066 - in reply to #244064 |
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