I have a 2002 crown vic that cranks but wont start
a couple of things that I have noticed. I got a new battery and the dash shows low battery.
i switched the fuel relay with another relay and same. car cranks but wont start
the obd reader doesn't even get power. the dash does light up though.
the only thing that I did recently was get the headlights changed
The Data Link Connector gets power from Fuse 12 (30 amp) in the underhood fuse box (Battery Junction Box).
The same fuse provides power to the Powertrain Control Module and the PCM Power relay.
So check that fuse. If it doesn't look fried use a test light on both of its test tabs to make sure it's getting power from the fusible link that feeds it.
Thanks I checked it. its good. i think its a PATS issue maybe the key just lost programming
You're welcome. But a PATS issue wouldn't kill power to the DLC (data link connector). Did you use a test light on fuse 12 to confirm it's getting power?
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How will you be able to diagnose a potential PATS issue without being able to connect a scanner to the DLC and communicate with the PCM and PATS module?
its so weird. when the key is in off position the obd lights up but cant connect. when it put the key in on position the OBD turns off
also I found a parasitic drain coming from the horn fuse so I removed it. still nothing
Maybe grab a test light and check the Power and Grounds on the DLC connector
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See if you're losing Power (on Pin 16) or one of the Grounds (on Pins 4&5)
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Just be sure not to touch any of the communication network pins while doing your tests
How exactly does it show a low battery?
Also, did you put LED headlights in it?
not LED
the needle meter on the dash shows the battery is on low
Update
with the horn fuse
the obd reader flickers when car is off
without the fuse it stays on. but when the key is turned the obd shuts down. I'm so lost here. its clearly an electrical issue right?