Problem with old car (engines, replace, Chrysler, battery)

[kikto]

So, I bought this guy on Monday last week and it ran smooth, no check engines, and it didn't seem to have any problems. This 1998 Chrysler Concorde was a steal, I needed a car since my last car died, like dead, dead. Anyways, one day I was going to work which is less than 4 miles and the check engine light came on, okay no problem. It was a P 1684 so I looked it up and haven't gotten around to actually cleaning the battery terminals like I wanted. (its snowing, its cold, and its a PITA to get to the battery in this car) THEN ALL THE LIGHTS STARTED COMING ON! And I was like, Holy F*** this thing is about to explode! It didn't, it actually still runs perfectly fine. My thought was that the instrument panel is busted. So then, since I'm still broke, of course I messed around with it. Right now what I have is, when I start the car the instrument panel just... Stops reading everything and throws lights around like its at a rave party. (Okay, maybe not that many lights) The meters all read 0, and the miles reads no bus, it doesn't even tell me if I'm in drive, reverse, neutral... So then I did some tests:

- Reset the computer by removing the relay for about a minute, nothing still "dies"
- Tried changing the relay with my headlights, nope.

Friday I'm going to see what they can do with it since they sold me the car anyway but I have a feeling I'm going to get a no, go away. Interestingly enough though, when I DON'T start the engine, the panel is fine, shows me everything, but 5 seconds after I turn the engine on it starts partying again. I haven't cleaned my battery terminals yet but I'm hoping when I do it fixes this but I wanted to get some more opinions on it. I fixed a lot of stuff on my dead 2004 dodge neon sxt but I've never ran into a problem like this...


PS. It runs as if nothing in the world is wrong with it...

Video link: https://youtu.be/yMJL7aG_27s

[TrapperL]

Strange that it still runs. The "no bus" indicates the PCM is dying. Had this happen on the last Mopar I owned and that was in 2000. An aftermarket PCM is a much, much better unit than the factory crap. They don't last forever and yer about due for one. It is a plug and play type unit. Seems to me that I paid about $250.00 for a performance unit which was cheaper than the factory unit.

[Vision67]

You might just have a loose ground. Also, the terminals on the battery need to be clean and I think the negative terminal has several ground wires coming to that post.

Look here for repair ideas: General Discussion (Second Generation) - DodgeIntrepid.Net Forums - Dodge Intrepid, Concorde, 300m and Eagle Vision chat

[txtea]

Clean your battery terminals 1st....seen corroded terminals and battery cables do funky things to electrical systems. Check altenator output also.

[kikto]

Update: Changed the battery to a new one, probably didn't need to but it fixed the instrument panel, now the only thing that happens is it sometimes doesnt show me if I'm in drive or not but I'm still getting the code. While replacing the battery I noticed that the connector is broken and that the positive terminal and connector were both corroded so, going to have at it again today and replace it.