2007 mazda 6 141k miles auto 2.3 dutatec it made a gnarly burning eletrical smell and went into limp mode takes off very weak almost no power acceleration until i pick up speed then its stuck in 4th i also noticed the security light on with the horn stuck on etc any help would be much appreciated

 

Drive it / tow it to Mazda for diagnosis.

 

no thanks ***** I'd rather fix it myself

 

Dont know what a gnarly electrical smell is chap but lets put that aside. you smelt something electrical. therefore something electrical is burnt out. whatever has burnt out is either a faulty sensor or something else which has burnt some wiring which goes to a sensor. Whatever it is has told your electronic control module to cut its normal functions to a level which is deliberately designed to encourage you to give the menders piles of money. Clearly you dont wish to do this, so at the risk of being called a moron first check any obvious additions to wiring ie aftermarket junk like crashcams hi fi"power amplifiers" look for bodge connections or overloaded cables. Check the fuses to see which one have blown ( if any) this may give you an idea where to start. find out here the cabin air inlet is and look for signs of electrical damage in that area.Finally if all else fails, call yourself a moron for not being clever enough to outsmart the boffins at Mazda and cough up cheerfully. By the way you might get quite a bit more help if you keep your replies on the polite side of condescending.

 

well it seems to be an alternator or something eletrical it has a security light on it tripped the bcm out the blinkers wont work etc could the bcm be burnt?

 

Never heard of a BCM and alternators dont ordinarily have "security lights" on them. Sounds from your descriptions that you have rather limited electrical knowledge. You are either trolling or genuinely trying to get something you know very little about fixed without spending lots of your hard earnt cash. Let's assume the latter. Do you know anyone at all who knows what they are doing with cars?Your best option is to find someone who can look into the problem and at least recognise the components which appear to have sustained damage. Getting eyes onto the problem is important, you arent going to get very far without someone looking your car over. Maybe if you could take a picture showing the burnt wiring or components , someone might recognise what part may be dmaged?

 

it has had the horn stick on before with security light and ran fine just had security light now it seems worse I've been a mechanic for 15 years but this is more in depth electrically trying to figure out why it would have security and limp mode with flashing battery light

 

Sorry Adam, I had misunderstood your english , by" security light " you are referring to a warning lamp? So the horn sounded and the alternator warning lamp was lit? It is my guess that there is a short circuit on the alternator control circuit and the horn feed. Quite often on older style cars, both these feeds come straight off the battery with a big inline fuse because the horn takes a lot of power and the inbuilt alternator voltage control likes to be connected directly to the battery so there is nothing to interfere with the power reference voltage it receives. If this fuse has blown, it means that there has to be a fault somewhere on this circuit. It will not help you to just replace the fuse, you need to find where the short circuit or burning is occuring. You have to do this by pains taking good old fashioned looking for burns or bare cables or poor connections. Just replacing the fuse and waiting to see what burns ruins electronics and sends people to the hospital. My guess would be that your car will not charge its battery any more which is why your electronic control module has put you into limp mode. A good place to start is non standard wiring. Check any home made or professional non factory wiring connections first as these are notorious , also check for rodent damage since the plastic which coats the cables is very good for rodents to wear their teeth on.
I am only guessing at possible solutions which are easy to do but take a lot of time. If you take it to Mazda, of course you would be paying for a lot of this time so it may save you money. However, if you dont find anything which is looking wrong/ burnt / damaged , how can you find electronic issues without all that specialist equipment?