1996 Pontiac Grand Am Reversed Polarity

Tiny
96 GRAND AM
  • MEMBER
  • 1996 PONTIAC GRAND AM
Electrical problem
1996 Pontiac Grand Am 6 cyl Front Wheel Drive Automatic

I installed the battery in reverse polarity and tried to start the car, it cranked but wouldn't start. After realizing my mistake I corrected it, the engine still cranks but will not start. I checked all fuses and tried to find a fusable link but didn't find one. Did I fry the computer? How could I be sure? There usually aren't returns on computers. Whats the best way to diagnose my problem? Is there any point in using a code reader or is all the data lost?
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Saturday, April 10th, 2010 AT 6:12 AM

5 Replies

Tiny
MMPRINCE4000
  • EXPERT
A scan tool will tell you if computer is cooked, but most likely there is a fuse or fuseable link/relay blown.

Remove and check each one, one at a time.
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Sunday, April 11th, 2010 AT 7:36 AM
Tiny
96 GRAND AM
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I have checked every relay, they all are fine and I would have to tow my car to have access to a code reader. All fuses are fine. The local parts store says I would not be able to get a code unless the chk/engine light is on which it isn't. Any other ideas, is it possible to diagnose the computer any other way?
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Saturday, April 17th, 2010 AT 9:44 AM
Tiny
MMPRINCE4000
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96 and above are OBDII and diagnosis can only happen with a scanner.
A scanner will tell you any problems with PCM, but if you don't have access to one,

Check spark using plug grounded to valve cover bolt, if OK, then check fuel by spraying starting fluid into intake, if engine runs, then fuel issue, if not then spark.
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Sunday, April 18th, 2010 AT 8:39 AM
Tiny
96 GRAND AM
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I have fuel pressure but no spark. I checked fuel pressure at the fuel rail. No luck with starting fluid into the intake. As I mentioned I don't want to pay for a computer if it is not the problem, I'm not sure what you mean by OBDII. I can get access to a scanner but will it tell me if the computer is fried?
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Sunday, April 18th, 2010 AT 9:57 AM
Tiny
MMPRINCE4000
  • EXPERT
A scanner will check PCM for any errors, so start with the scanner.

In 1996 ALL cars sold in U.S. Switched to OBDII (on board diagnostics) from the older OBDI.

This is more sophisticated and is used for stronger emmission laws that went into effect.
They also mandated a common diagnostic port design.
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Monday, April 19th, 2010 AT 9:12 AM

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