Thought ide kick off the section with a bit of tech talk.
Its an idea ive been kicking around in my head for a while, its not totally fictional either after telling a friend about it he has partially developed the framework for a DIY multiplexing it just needs further coding and hardware circuits doing. Its more of a proof of concept and it did work.
I know multiplexing scares the crap out of most people, and its true its abit of a nightmare on newer cars. The main issue is the lack of access to diagnostic systems though not the concept itself. When something goes wrong and you dont have the correct gear you are in the dark.
The benefits are huge, in a race car you get way less wiring so save weight and alot more reliability. On a road car you get that + cool features, control your cars system via a phone. Use your bluetooth as a Key to start the engine rather than an actual physical key etc the possibility are endless.
For those non electrical type the basics of multiplexing are as follows
standard wiring for every item on a saxo at the moment is there is a wire that goes from a switch, say the indicator stalk, via the hazard button, then a relay then splits off to each and every indicator on the car. A break in the circuit can be literally anywhere in the car body as the lights are at each corner of the car.. and as a result wiring wise, its fairly heavy.
Now imagine you had a central computer in the dash. you have one wire to the indicator stalk, one wire to the hazard switch. These are quite short since the computer is located in the dash itself.
Then you only need one single wire running to the rear of the car, and one single wire running to the front. Which then connects to a cpu at each end of the car, or nodes to give them a proper term. The single data wire allows the central cpu to send a signal to the node to turn on any circuit thats on that node.
- you save weight
- you have the ability to do bulb diagnostic tests since you can sink a tiny tiny current through the bulb to check the filament is intacked
- you don't need a relay anymore as flashing can be controlled via the cpu
- with only one wire and a live running to each sub cpu at the front and rear of the car you have less chance of breakage. If there is a break the central cpu will know that one node has a fault and can inform you
- all the switches are to ground - there is a tiny amount of current behind the dash so in the event of an accident there is zero chance of a fire.
once you have a system like that its easy to add extras, for example. The fan is wired into the front cpu, and the engine temp is wired into the central ecu. Keeping the fan running for 10mins if the car temp exceeds a certain threshold requires no extra wiring atall. Just a line of code.
Theres a system on the market already, i think it probably costs 1-1.5k which i doubt is in anybodies track car budget here. But on a 50k race car its a bargain!
Or if its got a speedo feed to it, adding features like
- max speed reached
- average speed
- over speed warning for the road
would all be straightforward to do.
This video explains alot about their system.
http://www.isispower.com/V8_interview.php
The one im toying around with would be alot cheaper mind. probably in the relm of £150-200 then you would have to make up your own connectors + waterproofing for the external nodes. It would be flexible though, the central cpu would have a screen to show any errors and bluetooth functionality is an option too.
No guarantees It will ever get done though but if i make any progress I will update this thread.
Interested to here other peoples opinion on it, anybody looked into it themselves? Or might be considering it now?
Aftermarket multiplexing..
Linear Mode
