Strange fault with car lights

[audioguru]

But here in Canada we don't have a Queen, her huge staff and her castle to pay for.
Electricity is fairly cheap and inexpensive natural gas comes from the ground.
Some of our cheap oil products like gasoline come from nearby.

 

[arunb]

newer cars aren't always wired directly from the reverse light switch, to the bulb holder - some vehicles have the switch connected to a BCM input (Body Control Module) then the BCM switches an output internally, or via a CAN message to another control unit, which does the switching

Thats complicated. So whats the advantage of using a CAN bus system ??

 

[debe]

Makes them mutch harder to fix & more costly to fix, at least here in Austalia. Ford Aust use this system.

 

[adamey]

Thats complicated. So whats the advantage of using a CAN bus system ??

There are many advantages and a few dis-advantages.

- You can use a cheaper signal switch on your clutch, brake, transmission reverse instead of a larger current carrying switch. As such, the chances the switch would wear out goes down since it only signals the computer.
- You can incorporate logic (features) very easily. For example, fog lights need to turn off when high beams were on. Previously this required additional high current circuitry (usually relays) to switch the lights. Now it becomes a "decision" of the computer.
- It saves wiring. Instead of running bunch of current carrying wires to your trunk (boot) you can run a single positive cable and 2 CAN bus wires to a computer module. Then run shorter current carrying wires to all your "local" loads.

 

[Mickster]

To elaborate upon what adamey has posted, many years ago, vehicles used to just have a wire/multiple wires to each component which required power/ground/signal etc. This scenario could span the entire length of the vehicle, or even longer, considering the eventual routing of a wiring harness.

The addition of more and more electrically and electronically controlled equipment neccessitated either more physical wiring, or a different solution.

CAN-bus, LIN-bus, O-Bus (same as M.O.S.T.) etc. provided an alternative by only requiring power, ground and signal wiring between each control unit placed in the most suitable location. From that location, the neccessary inputs/outputs only require minimal cabling runs to devices, as opposed to the previously employed system.

An example of older technology versus new technology can be illustrated with cruise-control.
Older technology required a separate actuator for the cruise-control, which had to have it's own wiring for power, ground, vehicle speed, cruise on/off/recall switches, throttle position, clutch pedal position, brake pedal position, etc. This actuator was connected, by a cable, to the throttle body on the engine and actually moved the throttle butterfly valve mechanically.

Newer technology already incorporates "drive-by-wire", where the accelerator pedal is no longer mechanically connected to the throttle body butterfly valve. Instead, a pair of potentiometers are housed within the pedal assembly and supply pedal position to the Engine Control Module. From the pedal position value, engine temp value, engine speed value, engine load value, intake mass air value, current vehicle speed value, H02S value, etc. the ECM calculates the most appropriate throttle opening and sends a command. Feedback potentiometers, in the throttle body housing sensor, report current throttle position back to the ECM.

Since all of this information is already being evaluated, re-evaluated and continually adjusted, on the bus, to add cruise control is a trivial matter. No extra wiring is required, only the addition of an extra switch and a quick re-programming function of participating control units.

HTH.

 

[transistor495]

Hee, hee, haw, haw, ho, ho.
Your car has a tiny 1 litre engine?
Does it have 3 wheels like in India?

This is a typical impressive 3 wheeler you see much in Indian roads..

**broken link removed**

It not only saves the cost of a tire, but also very economical and spacious, yet providing a very good riding control too.

I wonder why Canadians failed to implement this impressive riding concept, heehoohoobowbow

 

[canadaelk]

audioguru: You are wrong. We do have a queen in Canada and, yes, she costs us $s (and there are also many more queens on Church or Davie St.)
I remember the 3-wheelers, growing up in post-WWll Germany. Motorcycle front-ends. No need for a diff. trany (or tranny?). Loaded the wrong way, doing a sharp turn to fast, they would often end up on their sides. Funny!
E

 

[audioguru]

I forgot about all the Queens on Church St in Toronto and I didn't know about them when I was a kid in what is now called Hongcouver.

Cars in Canada must meet crash regulations so that toy 3-wheeler in India is not allowed. I am surprised that the tiny SMART car meets the regulations but it is very expensive for its size.

 

[arunb]

It not only saves the cost of a tire, but also very economical and spacious..

the CNG ones are better, they produce less emission, nowadays there are better ones available, that can carry more load and are more efficient.

 

[danrogers]

had another look at the problem last night, certainly not a bad earth because there is a common earth all around the cluster, and its not the bulb holder either.
I measured the current in series and there is only about 100ma going through the bulb.

really confused now!

 

[Nigel Goodwin]

had another look at the problem last night, certainly not a bad earth because there is a common earth all around the cluster, and its not the bulb holder either.
I measured the current in series and there is only about 100ma going through the bulb.

really confused now!

Weird lighting faults are almost always due to a poor earth, it means the lights earth via another bulb.

Try running an earth wire from the actual body of the bulb to chassis.

 

[Ian Rogers]

Danny!! You said that the 12v dropped off when the bulb was inserted? if there was an earthing problem you would have seen a voltage on the earth side of the bulb... As the voltage dropped off the live side, it would appear as if there is a resistive component on your wiring or switch... Find out if the reverse switch makes a positive or a ground... If it provides a ground the grounding wire will almost certainly be on the gearbox near the switch.

 

[danrogers]

i don't think its an earthing problem, I connected an earth near one of the working bulbs using croc clips and also by-passed the bulb holder itself, still no go.

that's it mate, as soon as you connect a bulb across live + gnd the voltage readings drop to nothing, so no potential difference and like i said about 100ma flowing through the bulb.

I think I will have to start looking at the switch wherever it is lol

thanks

 

[Nigel Goodwin]

You'll probably find a bulb with a couple of wires soldered to it more useful than a multimeter - as the old bulb is presumably OK, solder a couple of wires to that, connect one to chassis and use the other for testing. The obvious place to test is the switch itself, both sides of course.

 

[danrogers]

thanks Nigel, I think the switch is about the only thing it could be, now to try and locate it lol