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I wanted to update you. I made prototype (but on 5" cables I had in stock, final solution will be probably 10-12", I need to do some checks in my Giulia), got quotations on crimped individual cables of required lenght, optimized whole design, and I can tell you more about final solution.
First I will offer 2 seaparate 12 pin and 8pin extensions - that will be way easier to plug/manouver around/wrap etc.It will be also quite compact design without spare big housing. First 1" of cable beside connector/socket won't be too flexible (because heatshrink - probably bit shorter than on prototype shown below), but then there will be flexible plastic shield on top of cables with bit of loose inside, and on top of this I will put likely another fabric protection tube - here I need to do bit of research - maybe there are ready reinforced textile protection shields for cable looms, so could use such instead of separate plastic and textile -details like this still to be sorted out, but such unlikely will have impact on price. It will also be more discrete - definitelly black colour of any outer layer, so it does not catch an eye of dealers doing work in the car - just in case they get picky.
Pricewise 12 + 8 pin bundle will also be cheaper than intially estimated, even at small batch. Estimate ~$65 final price for the moment for such bundle if this stays as niche product (mean like 50 bundles/year). I guess some of you may be happy with just single bundle (to protect mainly original car loom), others may want to also stick one on SGW side (especially Stelvio users where access to SGW is poor/out of visibility), so then dual set would be required. I may offer you also metal tool to easier extract connectors from sockets (release lock while pulling) - I was thinking about stainless steel tool, but would need to draw it first and get quotations from companies who could manufacture such for me. I very guess it will be 5-10$ range - but it is only guestimate.
Here are picturs of prototype of SGB extension (I made it only on 12pin version, product will consist also 8pin extension made the same way), mid section will be longer by 5-7", will be black and probably covered by textile shield:
99432

99433

Comments welcome
 
Fantastic @epsonix , I will be getting a 2019 car soon and will need both the SGW bypass so I can use MES4.6 and when you have this ready, the extension so I can leave the SGW bypass more accessible but plugged in all the time but only remove it for dealer work, so easy access to do that will be handy. I will contact you here or on the UK forum (it's me ;) mg ) once my car is confirmed to order the SGW bypass.
 
Discussion starter · #28 ·
Very interested.
Question: I’m confused by 8 pin and 12 pin. Isn’t it just an extension cable for the bypass? Why are there different pin numbers.
There are two plug sockets in the SGW, an 8-pin and 12-pin. Right now the OEM setup is a single cable with both sockets, the patch harness will have separate cables for each socket to make it easier to stow the cables under the dash, and also to make the overall socket size smaller (won't use a large socket to accept both plugs, instead will have the two smaller sockets.
 
There are two plug sockets in the SGW, an 8-pin and 12-pin. Right now the OEM setup is a single cable with both sockets, the patch harness will have separate cables for each socket to make it easier to stow the cables under the dash, and also to make the overall socket size smaller (won't use a large socket to accept both plugs, instead will have the two smaller sockets.
Understood, thanks.
 
Interested as well.
 
At this very moment production of first small produciton batch is pending. We will test excessive amount of extensions plugged in series (like 6 sets), try proxi reprogramming, drive with these in for a few days etc, and we will be available to quote final price and ship late this week hopefully.
 
We went for 10". In terms of twisting - CAN standard does not require such (even for high speed and on full allowed lenght), they say in standard only about parallel wires what I understand as wires routed more or less together (similar length, the same route in one loom). In general CAN is low speed bus (like sub 1Mbps, vs e.g. Ethernet where you have 100 - 1000 bigger speeds so things matter by levels of 2-3 magnitudes more) even at fastest rates allowed. Note also that as far as I seen, the car itself does not have twisted cables within its looms for CAN connections, and even car connectors pinout on SGW plugs (and other units within car) are not that you go even neighbour pins or any kind of attempt of getting continous and matched impedance through connections.
What we did was that we have 2 full turns (720 degrees) of the whole extension loom (it removes stress on individual cables, and allows easier bending) so all is kept more or less in parallel - I'm sure that is fully correct for CAN, especially as we only introduce pretty short harness in between (comparing to max lengths allowed on CAN for specific bitrate).
Of course twisted pair cables can only help, the same like shielding, but that is not used in the car design, and so we won't
I hope you agree, or otherwise we can discuss it (maybe offline to avoid mess on the thread).
You know, right now all is possible, we can twist individual CANs within extension harness, but it adds IMO unnecessary work and brings no real value (vs rest of the car looms not twisted, connectors not impedance matched etc).
 
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first pre-production pair ready:
100142


we tweaked production instructions based on first built pair, and waiting for delivery of different heatshrinks than we orginally planned - tomorrow we shoudl receive all, and so complete first batch.
 
I fail to see why these extension cables are helpful other than ease of access. Why can't there be an intermediary connection to connect the SGW Bypass to? Isn't this the point to not have to connect and then disconnect from the car's SGW module to save wear on the delicate connectors? If so, then a high wear connector with an accompaning SGW Bypass shouldn't be used?
 
I fail to see why these extension cables are helpful other than ease of access. Why can't there be an intermediary connection to connect the SGW Bypass to? Isn't this the point to not have to connect and then disconnect from the car's SGW module to save wear on the delicate connectors? If so, then a high wear connector with an accompaning SGW Bypass shouldn't be used?
I have the same question. Access isntvan issue for me. Id like a quick connect option to easily swap between sgw and bypass module or even possibly a way to connect both at thecsame time and a switch back and forth
 
There is multiple of options and preferences from customers possible, for some it may not be solution they need or ask for, others woudl be happy. I was requested if I can prepare only extension leads, as only such was expected as quick enough development, using already stocked major components, which will tick boxes for some customers. The goals were in one hand to avoid wear of original looms (actidential damage of lock or cables which are not that thick), in other allow possibility of bringing mid point (idea of putting 2 sets of looms in series) into accessible place (see where SGW stits e.g. in Stelvio - out of view, above steering wheel column and metal rails, poor access with tips of fingers only), but all maintaining fully passive original loom structure when SGW is back connected, so no components which may be more likely to interferee with CAN busses or lower MTBF in some way during daily use.

I sniff that you would best prefer solution where there is a box, which you can easily command (by e.g. toggling switch) to get either bypass connections or SGW connections. Such design woudl not meet main goal requester came to me with (only wires, no active components when running car), as well would be new electronic circuit design, so wouldn't have chance to jump into my project queue in any near time ( to be fair not sure if would ever jump, as most of people are happy with just bypass, and some will be happy with extension leads, so market coudl be small and never pay off development/production preparation/building production tester/testing etc). Extension cables I could test on my current tester with only small adapter built and quick change to tester firmware.

Basically with having series of 2 extension leads, in the middle point you gain possibility of putting SGW bypass or rejoin and that is what was requested and in some way ticks what @The_Dude expects as well (to be fair I'm not sure if you could place in parallel SGW bypass while keeping connections to SGW - I sniff clash cased by SGW transceivers).
 
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Discussion starter · #39 ·
Exactly, my original concern was wear and tear on the OEM-side cable connector (also, it is somewhat difficult to access). The OEM plugs were never intended for multiple cycling, eventually they wear and connectivity issues can develop. With this solution, one set of extension harnesses is connected to the OEM plug side. The other set of harnesses is connected to the SGW. One connection cycle, no risk of wear. The harnesses, when connected together, maintain SGW function as original. When you need to perform maintenance, or just want the SGW bypassed, the harnesses are unplugged from each other and a bypass is connected to the OEM harness-side set of cables.

The proto harnesses look great, too!
 
Exactly, my original concern was wear and tear on the OEM-side cable connector (also, it is somewhat difficult to access). The OEM plugs were never intended for multiple cycling, eventually they wear and connectivity issues can develop. With this solution, one set of extension harnesses is connected to the OEM plug side. The other set of harnesses is connected to the SGW. One connection cycle, no risk of wear. The harnesses, when connected together, maintain SGW function as original. When you need to perform maintenance, or just want the SGW bypassed, the harnesses are unplugged from each other and a bypass is connected to the OEM harness-side set of cables.

The proto harnesses look great, too!
You would need two sets of harnesses to achieve what you are discussing, as one set of the factory connectors will see wear. To avoid this entirely, there needs to be an intermediary connection that'll take a high cycle of connections/disconnections to insert the SGW Bypass when needed. I would not want a switching type box as Epsonix stated the ROI wouldn't be there.
 
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