What Car?

[SiC]

I don't know why people are scared of CAN bus equipped cars. It's a simple networked bus that has been around for literally decades. Ok you need more diagnostics tools to fix vehicles and some manufacturers go overboard with modules, but it's not that hard to diagnose and fix issues. Often easier too as you get more diagnostics information out.

[Eddie Honda]

The last Mercedes not to have Canbus was the early pre-facelift W210 e- class which although ridiculed for its rust issues is in my opinion less actual rot prone than the Sainted , granite W123 and W124. If you can find a rust free or

They're fucking terrible for rust. Father Honda has a '99 E300 estate and he had to badger MB to replace the front wings under the body warranty. It was under ten years old at the time. The front suspension collapsed (TADTS - RHD, so apparently SA built) around the 11 yo mark. Various other rusty spots and when he got sick of it, not longer after, the rear arches were hanging. That whole experience pushed him to become an Aldiwanker (Q7)

Our Volvo 240 was in far better shape at the same age.

Bodywise, that MB was steaming turd of a car.

[panhard65]

I don't know why people are scared of CAN bus equipped cars. It's a simple networked bus that has been around for literally decades. Ok you need more diagnostics tools to fix vehicles and some manufacturers go overboard with modules, but it's not that hard to diagnose and fix issues. Often easier too as you get more diagnostics information out.

Sorry but canbus is pointless shit. What was wrong with having one wire going to a bulb and an earth it worked perfectly well for years. Now there are modules for each fucking light why ?? It is a bad example I know but Vectra's having variable voltages to operate the stop lights totally daft. It might work well in indoor environments but in cars it is a case of when it goes to shit not if. I had a Trafic van in for weeks over Christmas where the wiring loom was corroding inside the insulation causing resistance issues which in turn lead to the fly by wire throttle revving the van up randomly. Just why is all I can say.

[AutoshiteBoy]

In my idle moments today I have browsed a few C70 cabriolets.....Never fancied one before but I have to say they look good value for money

Failed Bentley design innit?

[AutoshiteBoy]

Was this the model with brake modules on a sell-by date? I remember some tale about only getting so many strokes of the pedal before life expires....Even the local Merc specialist was a bit cagey about it when he was trying to flog his E Class a year or two back.

Aye. M-B offered a 10 year gesture of goodwill.

[AutoshiteBoy]

I took one of those E-klasses in part-ex around a decade ago and had to scrap it as the front suspension rotted out. Absolute shite. Early ones also stunk of fish due to a type of plastic they used in the heater pipe ducts.

[SiC]

Sorry but canbus is pointless shit. What was wrong with having one wire going to a bulb and an earth it worked perfectly well for years. Now there are modules for each fucking light why ??

Because if you have a wire for every signal to a control unit, you end up having a fist sized loom that goes from one end of the car to the other. You know well how thick a classic Bentley/Rolls Royce loom is and they're comparatively simple compared to what people want feature wise in a modern car. That thick loom adds not only significant cost in terms of materials but also harder to route (thick looms don't bend as easy), significant extra weight (modern cars already heavy, so every kilo counts) and limits placement of control units. As an example if you had separate lines, you'd have brake light, left indicator, left side, right indicator, right side, reverse, fog, tailgate motor, tailgate light, tailgate button, tailgate closed switch, boot light, electric boot lift actuator open signal, actuator close signal, boot lift switch, reversing sensors, etc wires from the front end to the back. Also of sufficient current capacity and associated insulation around that. Also if you don't have all those options installed, do you leave the loom wires in there? If so, that's extra unnecessary cost and weight. If not, then you have multiple SKUs to keep track.

Then also you need other parts of the loom for other functions elsewhere in the car. Window wires, electric adjustable seats (plus wires for memory function), puddle lights, central locking, la la la la.

Instead of all that bollocks, you have two differential pairs and a few high current feed to the back (as separate fused circuits for safety). Then a bunch of modules at the rear to convert that CAN signal into driving those lights. Smart relays so to speak.

Likewise if you have specced reverse parking sensors, you have a small module that connects to that same network. That can send back it's information to not only the sound system but also can be easily disabled if a trailer is hitched. Or if it's broken? Well you can use the same network to interrogate to find out what's wrong. If you didn't have that you'd have to manually test the sensors and wiring to figure out from scratch the problem.

Electronic tailgate? Another module that is fitted into the place for it. That can then talk back to front if you hit the open button. Also a remote fob can talk to the tailgate to command it to open. You could have separate wire to trigger that but that's already additional wires to the big bundle.

I could go on with more examples but essentially manufacturers did it for a reason. It cost them a lot of R&D to do it and they wouldn't if it didn't had a significant benefit. Whether to cut costs or aid saleability.

It is a bad example I know but Vectra's having variable voltages to operate the stop lights totally daft. It might work well in indoor environments but in cars it is a case of when it goes to shit not if. I had a Trafic van in for weeks over Christmas where the wiring loom was corroding inside the insulation causing resistance issues which in turn lead to the fly by wire throttle revving the van up randomly. Just why is all I can say.

Driving lights with PWM is trivial to do electronically. You already have the power electronics to switch it on and off, so if you switch it quick with a variable duty period you change the brightness. A concept that I used to teach art students in their Arduino lessons and a practical in digital electronics been around nearly from year dot.

Corroding loom? The problem you were having with the FBW pedal was exactly the problem with individual wires for each function. That pedal must have had individual wires for each potentiometers plus low voltage power wires - at least four and possibly five wires that are analogue, noise prone. If that pedal with on a CAN bus you wouldn't have had that problem. A error would have been thrown up on the ECU with a high network message error count. No random revving as the message have corruption detection and the ECU will know the signal is implausible.

You'd have exactly the same problem if it was a brake light wire going to the back corroding too. When it fails an MOT because the light isn't working/dim/flickering. Or blows a fuse/burns out the switch everytime you hit the pedal. Except you'd have to find where in the loom it's damaged and repair it. Or strip out the whole loom and replace that wire. Or bodge it into the loom as an additional wire.

[AMCrebel]

^agreed. I was going to post that but as usual someone else did it better. Also canbus is used in planes. And manufacturing.

Unfortunately the producers don’t always think (or maybe even care) about what may happen as the vehicles age.

That PWM for rear lights is a great idea - twin filament bulbs use more resources to produce and we waste half that as we have to throw them as soon as one of the two filaments dies. Superseded by LED which uses PWM now anyway.
Another great thing about canbus is the way it can “redeploy “ rear lighting as required - pretty sure Vectras do this, BMs and Rover 75s do - they can run a brake light at half power if the rear light on that side is dead.

[AutoshiteBoy]

The problem is, speaking as a warranty engineer, the wiring looms and the like are sub contracted to the lowest cost producing nation. The components, material and build are generally shit so when there is a problem, the car is approaching scrap value.

[cros]

I took one of those E-klasses in part-ex around a decade ago and had to scrap it as the front suspension rotted out. Absolute shite. Early ones also stunk of fish due to a type of plastic they used in the heater pipe ducts.

I had a 100e that did that, scrubbing the passenger seat with Vim sorted it.