PV - check for diagnostic codes

[Jim S.]

Our 1996 is scheduled for PV at Bowling Green next weekend. I have been going through the manual and when I check for diagnostic codes I jump the 4 and 12 pins on the OBD-II connector and I get a C-12 code (Distributor Pulses). When I take it to a mechanic who has the code reader, the unit says no codes. Sooooo - how will Tom Barr check the codes before and after the PV test ride? This is a low mileage car that runs great, so I was not expecting any codes. Anyone else have the dilemma? Any suggestions?

[Keith B.]

Re: PV - check for diagnostic codes

is your check engine light on

[Jim S.]

Re: PV - check for diagnostic codes

No check engine light. All is well, except for the code when the 4 & 12 pins are jumped. I thought I could have the code cleared, but no code comes up using the code reader.

[James W.]

Re: PV - check for diagnostic codes

According to my Factory Service Manual, a C12 code means there are no diagnostic codes stored. It's like an all clear.

Jim

[Bill H.]

Re: PV - check for diagnostic codes

Our 1996 is scheduled for PV at Bowling Green next weekend. I have been going through the manual and when I check for diagnostic codes I jump the 4 and 12 pins on the OBD-II connector and I get a C-12 code (Distributor Pulses). When I take it to a mechanic who has the code reader, the unit says no codes. Sooooo - how will Tom Barr check the codes before and after the PV test ride? This is a low mileage car that runs great, so I was not expecting any codes. Anyone else have the dilemma? Any suggestions?

Jim, the C12 is the "NO Code" condition. Not sure where you got the Distributor Pulses but a quick look at my 96 DTC list doesn't show it. I can post the complete list if you would like it.

[Bill H.]

Re: PV - check for diagnostic codes

I didn't know you could jump the ALDL on a OBDII 96. Humph. Learn something everyday. Or are you reading the codes in the Speedo, with the ALDL jumpered? That's kind of cool, isn't it?

Yep, Dave , you read them on the speedo. The 96 is a bit different being ODBII. But on 92-93 and 94-95, you can pull the codes and clear them with the dash buttons. I even carry the code list and a paperclip all the time, especially on trips. I have the code lists if anyone wants them.

[Edward J.]

Re: PV - check for diagnostic codes

There is a code 12 in the earlier years OBD I systems, but not the OBD II systems When grounding the OBD connector under the dash as you did code 12 will flash three times, this is a all clear condition, a scan tool will not display the code 12.

[Jim S.]

Re: PV - check for diagnostic codes

Thanks all for your responses. My reference to code C-12 being Distributor Pulses came from page 54 of the NCRS PV Test Guide for 1990 - 1996. It should probably be updated to indicate that the presence of code C-12 is really an "all clear". That might keep some of us from having an anxiety attach while preparing for the PV.

[Gary J.]

Re: PV - check for diagnostic codes

If I had to prepare one of these new cars for PV I would be having an anxiety attack with all the electrical gadgets on them.

[Edward J.]

Re: PV - check for diagnostic codes

Thanks all for your responses. My reference to code C-12 being Distributor Pulses came from page 54 of the NCRS PV Test Guide for 1990 - 1996. It should probably be updated to indicate that the presence of code C-12 is really an "all clear". That might keep some of us from having an anxiety attach while preparing for the PV.

Jim, In the early years of computers there was a code 12, When the computer flashes code 12 only 3 times and the light goes out thats no codes stored, But when the light continues to flash code 12 then theres a problem.(dist. reference signal) about the only time I saw this code was when a do it yourselfer replaced his distributor cap and left out the metal electrical contnector that use to rest under the Ignition coil.

So I was thinking those older 90/91 corvette distributors with the ignition coils mounted in the cap had code 12. After that Corvette went to the pan cake style Dist. with the LED diode in the LT1'S. that gave them fits in the early years when they got mositure under the Dist. cap.

[Jim S.]

Re: PV - check for diagnostic codes

Dave, you indicate your response is for OBD-I and through 1995. The post was for a 1996 and it has OBD-II. It does respond just as Ed indicated. It also shows no code when connected to a code reader rather than using a jumper to get a codes.