My 1989 oldmoblie wont start, my lights come on when i open my car door but when i try to start it the temp. light comes on plus the clock go's out but the car lights don;t dem or go out.

Sounds like you have more than one problem.
The seat belt light is not on because of the door.
Are you saying the serpentine belt comes off the engine pulleys ?
And have you checked the battery and starter for voltage ? You need 12 volts at the battery and at the starter, and on the small wire from the starter to the key switch.

remove the key from the ignition and press the UNLOCK. its saying the alarm was triggered, eg if door was opened without first using the unlock on the remote. maybe when alarm was armed not all doors were fully closed. or you just reconnected the battery so the door was open without you ever pressing the unlock on the remote(which could be called DISARM the alarm)

Hello! I would suggest the ignition switch is the problem...Not the lock cylinder but the switch itself...If, to your knowledge it has never been changed, I would do so now...I can give the part number but I'll need to know if vehicle is automatic...And does it have a center console shift...

Guru....saailer

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adjust he pin in the door tothe right setting

U need to check to see if ur getting spark and fuel.

For the check engine light,you need to change the crankshaft sensor.For the temp ,to need to verify the the temp switch,if there is a short circuit in it,this will do like that.

open inside door panel and check elec. connection
to make sure . if that don,t do it check your fuses

that may be the alternator indacater lite your alternator may be going out go have it check

Did you have the same problems before replacing the alternator ?  Sounds like you have  a short to ground.

my dome light wont turn on at all and i dont know where the fuse is iv checked all my fuses and there fine could it be a capasiter