Multiplexing

[spider]

What do you think of multiplexing ?

From memory they started to introduce it around 2001 or so, although some 2000 vehicles are partly (wipers / lights) multiplexed, then they decided to do the whole car

I'm a bit up in the air about it really, as looking at the bigger picture I concluded the following (probably wrongly, although I'd love to hear some opinions)

Introduced to simply fault finding and wiring costs, although it adds complexity in itself, which may cause more problems than if it did not have this system (BSI faults etc, as no multiplexing = no BSI so one less item to actually go wrong)

Not keen on Com2000's, there was not a lot wrong with having standard column switches and a couple of wiper relays and a direction indicator (and that was probably more reliable too)

Problems with aged wiring on a conventional system will typically be isolated to that circuit, where as a multiplexed vehicle anything could happen (communication problems due to high resistance)

I note (as far as I am aware!) the C1 / 107 / Ago are not multiplexed, could this be Toyota not wanting this 'system'

Two faults that I have seen that I remember well:

(1) osf sidelight comes on when you apply the brakes (interestingly the brake lights did not)

(2) abs light permenently on (instrument panel was led not bulb) , car did not have abs fitted (!)

As a note: this topic is not meant as a 'dig' (for want of a better word) , I'm just interested to hear peoples thoughts about it all really. I'm not that keen on it generally as you can tell.

[Paul-R]

Well, as a consumer, on balance I have voted bad. Not that it will make the slightest difference to car manufacturers of course!

There are things about the C5 which just wind me up ever so much and I think that some are a by-product of multiplexing. Foremost is the slight delay with the lights. Try dipping or flashing your headlamps and it's like talking with an echo on a telephone line. Extremely unsettling.

But, the beancounters will have decided that overall it's to their advantage to go multiplexing. And, frankly, if it actually causes problems 6 - 8 years down the line then it's just bankable future money for them!

[Sl4yer]

Good idea, as long as it's done properly of course. As with all new (or 'new to application') developments, the early systems probably aren't the best.

James

[Citroenmad]

I voted bad, however i dont fully understand why its needed. Yes there is less wiring so less weight, and things can function together - auto lights etc.

However it does create problems which can be expensive to fix and hard to find.

I had a problem with my C5: when i indicated right, the indicator would flash three times, then stop and the headlights would come on. However the indicators worked fine if i had the sidelights or headlights turned on manually. It was a faulty comms 200 unit, which cost £175 new. Though some garages i asked seemed to think it would be the BSi, so i dont think its fully understood and the problems are not always easy to find.

[quintet]

I find it over complicated, even using the lexia doesn't alwas help, particularly when the lexia cant tell its left from its right (usually on airbag faults), I'm not keen on the 'lin' (?) sytem used on the lds warning system & i could live without the fibre optic wiring used on the high spec over complicated radios too. I could well live with out the BSI, it's awkward to diag' faults inside it & damn expensive to replace (fap system is pants too!)

[HDI]

Another issue that I loathe about multiplex is that it allows manufacturers to code components to the ECU so that if a faulty unit is replaced it needs to be coded into the system !! For most people that means a visit to the stealer !! I've heard that Ford take this as far as batteries !!
Potentially it's a good bit of technology but in practice it becomes yet another impediment to self maintenance. Wait until 48 volt systems are introduced , that will be fun !! Not !

[Clogzz]

Bad for us because it increases our dependency on them.