battery and brake light !

[4turbo]

hi all
i changed my cars engine to 4efte but there a problem that i can`t solve now !
what happened is while the engine is running the battery and brake lights goes on and off from times to time , it raise the RPM a little bit !
does it affect the engine and car electric systems if i don`t solve the problem ?
is the possible cause for this the alternator or the is something else like some loose wires left loose or contact together when we modified the electrical connection ?
thanks all

 

[dac69er]

is the battery being charged when the car is running? could be the alternator.

also sounds like it could be a bad earth

 

[H_D]

Had similar issues on my mates GT....It was the rear break light bulb which was bridging took us nearly 2 whole days to find the fault

 

[4turbo]

thanks guys for the advise i will check the alternator , did you mean the earth for the alternator or the main engine earth lead ?

 

[dac69er]

all the earths.

 

[wildchild]

check belt and all wires in the alternator for loose connection.