well I did some more trouble shooting. When I ground the Diagnostics terminal the car doesnt go into Dia. Mode, it does nothing. So I checked to see if the wire on the Diag. Terminal were bad( White/BLK)...nope they were good. So I double checked to make sure I was doing it right, yes You ground A and B terminal together and it goes into Diag. Mode and tells your codes. So I traced the wires all they way to the ECM under the passenger side dash....they were good. F**K I thought must be a bad ECM. I took out the ECM and checked it. It had a HyperTech PROM from 1987 in there, so Im assuming its the original ECM. I gave it alittle love tap and for S**TS and giggles I hooked it back up and left it hanging under the dash.

I turned the key on and grounded the Diag Terminal agian...!!!!!!!!!!!!!!!! It worked It went into Diag mode. It blinked 12 3 times....then blinked 51 over and over. Code 51 is the Prom. I took it out and put it back in, Cleared the codes by disconnecting the ECM fuse next to the battery for 30 secs, and started the car.!!VVRRRMMM fired right up perfect Idle was great and everything...after a few mins the light came back on and it the car began to run like crap agian. So I tried to Check the code agian, and same thing. I wasnt able to get into Diag. Mode. SO this is my question doI need a new ECM? From what I have researched a bad prom wouldnt cause the problems with the SES light, but a bad ECM would. Anyone know anything? I have been doing aloooooot of work on the car and everything is just about new now. !!! I Have the fever, and the only cure is Working Corvette. AAAHHH Im so close I can feel it Thanks!! Ryan

 

I got the new ECU fromauto zonetoday, and put it in.....Nothing,it does the same thing, does not go into Diag mode ( It must have been afreak chancethat it went into Diag. Mode that one time, a sign from the corvette gods!!!).So Im back to the same thing, I reused the old hypertech chip from 1987, so That might be the problem? I have gotten mixed signals. I have this book.. TPI swappers guide, and it has all kinds of good info in it. The book says a bad PROM wouldnt cause the SES light problems, but the new ECU from Auto Zone has a sticker thatsays that a bad PROM Will cause the SES light problems. Im so close Sooooooo close!!! [8D]Im gonna get there!

 

You need to go to GM and order a new PROM. Code 51 is "Replace the PROM".

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thanks MECH259! I will get on that first thing in the morning! The pics are a great! Thats where that hose went!!!! I keep you updated tommorw!

 

I went to a many junk yards and found a ECU out of a 89 Camaro5.7, Auto TPI,and putthe promin my new ECUmy car runs now, and sounds great at idleand a little throttle but onlyin Park. WhenI road tested it it surges and hesitates at anything more than 1/4 throttle. Is the prom differnt from what I need for my vette? Its a stock prom. My car as minor intake mods, and High Flow exhaust. Is doesnt give any codes now!

 

The proms are probably different. I will have to look up what prom yours takes when I get to the shop. [8D]