Electrical diagrams

Diagrams for post 2001 cars have battery as positive earth? Or am I missing something.
I have  problem with hazard lights ,they only work with ignition on which is an mot fail,

My word that is odd & you are correct. Someone didn't no their plus from their minus & another odd thing is those diagrams where they got the polarity correct has the battery voltage as 14v, the remainder have the voltage as 12v. Well observed.
I'm not as familiar with the Pektron system as I am with the Lucas but I know that the Pektron has twin indicator relays & they are controlled by the BCU.
I think fuse 4 should be intact if the warning lights are working with the ignition on, there are however two ground returns to the switch which terminate at header K109, one could be a ground return for ign on & the second for ign off. Look at that network after checking the switch.
M

Charlier wrote:

Diagrams for post 2001 cars have battery as positive earth? Or am I missing something.
I have  problem with hazard lights ,they only work with ignition on which is an mot fail,

What a bloody stupid requirement for roadworthyness!
Typical of mindless bureaucrats.......after all what use are indicators when a car isn't running!
 

Thanks I will look again at switch I assumed if it worked with ignition it was ok,where will I find the header you mentioned?
also the Scu May be faulty, it has had some mods made with a lead out of it to an external relay
 

You have obviously been looking at the circuit diagram, adjacent to that you will find the electrical diagrams. This covers all the connectors, their designations & whereabouts.
There is also a very useful key to the various bits of information on the diagrams, such as the distance from a connector to a device.
The understanding of this information opens doors to the electricals on the car, the two documents, used in tandem can make electrical fault finding so much easier than simply blasting into it.
There again I have an unhealthy interest in electrical & electronics.
M

Surely hazards need to work when all else fails. That is what they are for when stopped at the roadside and broken down.

They should normally. The rationale being that if the car needed to be left in a dangerous position due to breakdown or accident it could be left with the hazards running.- pretty essential if that happens to be on the hard shoulder on a so called 'smart motorway'. And it would be quite bizarre to have to leave the ignition on to run them.

You might be lucky with the MOT if the tester were to check them when the ignition was already on but i wouldnt bet that he would

It's quite easy to wire it all so as to be able to run the indicators only with the ignition on, and to be able to run the hazards with out the necessity of having the ignition on.
In fact some cars (European ones in my experience) are wired so as to use the indicator switch to operate the parking lights (side lights) when the ignition is off, they work so as only the parking lights on the selected sign work  so as to ease the current draw on the battery. this wouldn't be possible if the indicators were  still operable with the ignition off.
So it's absolutely bloody stupid for the authorities to have it as a requirement, indeed it sounds like overreach, probably  by some dribble dicked dipshit's miss-interpretation of the rule book