Cadillac Repair: car whont start, SIU investigation on a auto theft claim expert, EUO expert

Question
my girlfreind installed the new car battery with the positive and negative backwords and qwickly fixt it but now the instermant cluster dont turn on and car whont start i checkt all the fuseible links under the hoo an there all good what else coul be wrong its a 1989 cadillac eldorado

Answer
Hello,

You say you checked the fusible links under the hood. Does this mean at the starter? How did you check them? Blown fusible link wire is rubbery when pulled. I would tell you to reexamine the fusible links at the starter.
The problem is that there is no diagnostic flow chart for what can be damaged hooking up a battery backwards.
The instrument panel may just be a gauge fuse. Check the owners manual for fuse box locations, commonly Cadillacs have multiple fuse boxes.

When you ask what is wrong causing the engine to start after the battery was installed incorrectly, you could be dealing with anything. Wiring harnesses can melt in nano seconds. You can't always count on fuses or fusible links. I am also a vehicle fire instructor, so I definitely know what I am talking about.

You are going to have to do things the old-fashioned way and obtain a factory service manual and start tracing wiring harnesses up to the ignition switch under the dash on the top of the steering column. Possibly an ignition switch (not the key lock cylinder) or harness fried.

I don't remember anymore, if you have a black resistor chip on the ignition key, you have the VATS anti theft system. You could have fried that module or even the ECM.

I am at a big disadvantage not being at the vehicle. The factory service manual which you may find on Ebay or Craigs is the best tool you can have right now and in the future. It will prevent you from changing perfectly good parts on a guess.

Damage could be minor or major. I saw a main power wire being accidently put to ground (same thing done here) under the dash. Within a couple seconds the inside of the car filled with smoke, flaming plastic wiring insulation dropping on the carpet. It was disconnected and the dash harness was totally destroyed!
Hopefully we are not dealing with that.
Let me know what happens.

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