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Hi everyone Im new to this site but not new to honda, I have a huge problem on my hands. Working on the girl friends 2001 Civic EX auto, first computer was fried, changed it out took it to the dealer had it programed it worked fine, drove it out the dealer not even 2 blocks car shut off. Hook it up to the diagnostics computer, it cant read the ecu. When i first put the new computer in, I read the ECU with the car off with my scan tool, it read fine with no errors or issue. Now when I turn the car (engine started) on CEL flashes on and off, Fuel pump relay turns on and off, car idles retarded of coarse. CEL can not be checked. Also found out the the alternator belt was completely loose so I tightened it up. There are no blown fuses, car has not been in an accident, no water damage. I am stuck.

 
Rep Power: 811

sometimes an improperly grounded alternator can cause this.

 
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Had this problem on a customers car. Went through 3 computers and then changed out the alternator. Haven't had any problems since. Definitely change out the alternator.

 
Rep Power: 0

I figured that it was in the charging system since it only fries the computer when the car is on (engine ruining) does anyone know the specs on the alternator? I want to make sure it is that before I stick another ECU in it.