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this sounds like low battery voltage / a poor earth connection
so I'd double check the state of the earth connections, all should be tight and free from corrosion
check the main battery connections and the main earht lead connection to the engine
also check the state of the high power fuses in the under hood fusebox for corrosion and cracks
it would also be worth charging the battery to see if this helps
if it does its possible the new alternator isn't charging
if thats OK then I'd suggest locating the body control module (under the dash) and disconnecting it, cleaning the pins with some contact cleaner and then checking the state of the wiring loom to it
as its possible a poor connection to this module or the module is faulty
do you still need help?
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