No codes?
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Joined: Apr 2002
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From: Pittsburgh PA
No codes?
Had the Vette out the other day since it was warm. About 1/2 hour or so. the "SYS" light began flashing. I shorted out the 4 & 12 pins and no trouble codes came up. Voltage was reading 14.2. This is a 94 vette coupe. Anyone have any ideas. Could it be that the car sat for a month and that's why it happened? Everything appears to be working just fine. Any suggestions would be appreciated.
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Re: No codes? (wrlwynd)
The code can be cleared if the problem disappears, next time it comes on, immediately stop and pull the code.
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Re: No codes? (wrlwynd)
'94 should keep a code in History for 100 ignition cycles. Is this the procedure you used?
To display PCM codes, enter diagnostic mode by grounding terminal 12 of the DLC connector, then select PCM as the appropriate module by pressing "TRIP RESET" until "4.0" is displayed in the trip monitor area of the instrument cluster.
Select "Display Codes" mode by pressing the "TRIP/ODO" button until "4.1" appears, then press the "ENG/MET" button to display the first code. Continue pressing the "ENG/MET" button to display any additional PCM codes. When all stored codes have been displayed, or if there are no codes, the indicator "---" will be displayed on the speedometer. If it is necessary to step backwards through the list, use the "FUEL INFO" button. The top of the code list will be indicated by the "---" display on the speedometer.
To display PCM codes, enter diagnostic mode by grounding terminal 12 of the DLC connector, then select PCM as the appropriate module by pressing "TRIP RESET" until "4.0" is displayed in the trip monitor area of the instrument cluster.
Select "Display Codes" mode by pressing the "TRIP/ODO" button until "4.1" appears, then press the "ENG/MET" button to display the first code. Continue pressing the "ENG/MET" button to display any additional PCM codes. When all stored codes have been displayed, or if there are no codes, the indicator "---" will be displayed on the speedometer. If it is necessary to step backwards through the list, use the "FUEL INFO" button. The top of the code list will be indicated by the "---" display on the speedometer.
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Re: No codes? (nvlav8tor)
Pins are left to right. One to eight on top; 9 to 16 on the bottom. You want to ground pin 12 on the bottom row. You can connect it to pin 4 (which is a ground on the top row) or simply ground it to any available source.
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From: Pittsburgh PA
Re: No codes? (wrlwynd)
Tookj the vette out again today for a short run. Ran it for 45 mioinutes and the "SYS" light never flashed and no codes to get. Spoke to a GM mechanic who said if the voltage was low the system light could flash but after voltage went up it would not come on at the next start up.
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