OBD 2 scanner question
Thread Starter
Drifting
Joined: Feb 2009
Posts: 1,302
Likes: 2
From: colchester CT
OBD 2 scanner question
The engine light is on in my 96 and when I hook up the scanner it says that the scanner is not detected. I am not sure what to do next. When I changed out the heater core in the spring, I found a huge mouse nest and some chewed wires on the passenger side. I fixed all the wires. I had thought that they were all part of the alarm system but I am wondering if the computer is also on the passenger side and maybe some of the wires go to the scanner outlet. any thoughts or suggestions on how to proceed with this would be appreciated. Thanks
Race Director
Joined: Apr 2000
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From: Texas
The engine light is on in my 96 and when I hook up the scanner it says that the scanner is not detected. I am not sure what to do next. When I changed out the heater core in the spring, I found a huge mouse nest and some chewed wires on the passenger side. I fixed all the wires. I had thought that they were all part of the alarm system but I am wondering if the computer is also on the passenger side and maybe some of the wires go to the scanner outlet. any thoughts or suggestions on how to proceed with this would be appreciated. Thanks
On the '90 and up cars, the ECM (90-93) or PCM ('94-96) is located in the engine bay above the battery near the brake booster. The wires enter through the passenger side of the firewall.
Another simple test is to run the CCM diagnostics via a jumper wire across the appropriate pins on the diagnostic link. This is outlined in the FSM. While that doesn't conclusively prove the link is working relative the PCM, it will tell you if the link is active or not.
Thread Starter
Drifting
Joined: Feb 2009
Posts: 1,302
Likes: 2
From: colchester CT
I took it to advance auto and their scanner said the same thing so I guess I have a connection problem somewhere. Time to start digging I guess but I can't see any problems so far. I followed the wires from the connector to the computer and they look good so I am not sure what to do next.
Race Director
Joined: Apr 2000
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From: Texas
I took it to advance auto and their scanner said the same thing so I guess I have a connection problem somewhere. Time to start digging I guess but I can't see any problems so far. I followed the wires from the connector to the computer and they look good so I am not sure what to do next.
Going from memory, the PCM only has one wire that goes to the connector, at most two wires. The scanner connects to that line or lines and to a ground. These are clearly outlined in the FSM. Trace the two wires and and repair as necessary or run a new temporary wire from the PCM to the connector and a new wire from a ground location to the connector.
You DO have a FSM correct?
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
Take the car to Autozone and they'll scan it for free. If their scanner doesn't connect, then you've proven the wiring theory. If their scanner hooks up, then you know it's your scanner.
On the '90 and up cars, the ECM (90-93) or PCM ('94-96) is located in the engine bay above the battery near the brake booster. The wires enter through the passenger side of the firewall.
Another simple test is to run the CCM diagnostics via a jumper wire across the appropriate pins on the diagnostic link. This is outlined in the FSM. While that doesn't conclusively prove the link is working relative the PCM, it will tell you if the link is active or not.
On the '90 and up cars, the ECM (90-93) or PCM ('94-96) is located in the engine bay above the battery near the brake booster. The wires enter through the passenger side of the firewall.
Another simple test is to run the CCM diagnostics via a jumper wire across the appropriate pins on the diagnostic link. This is outlined in the FSM. While that doesn't conclusively prove the link is working relative the PCM, it will tell you if the link is active or not.
Thread Starter
Drifting
Joined: Feb 2009
Posts: 1,302
Likes: 2
From: colchester CT
Unlike the 94 and 95 where you connect pins 4 & 12 on the ALDL (16 pin) connector to get the codes, the 96 does not work that way. I don’t believe you can get the codes using the on board diagnosis as on the 94 & 95. For the 96, an external scanner or code reader has to be used. This is because it has the OBD2 codes and software.
Burning Brakes
Joined: Nov 2010
Posts: 855
Likes: 36
From: Crystal Springs MS
Yes I do have a FSM,http://images.ibsrv.net/ibsrv/res/sr...s/thumbsup.gif I don't know anything at all about pins, jumper wires ETC. I guess I will be learning. Based on what I have been reading though, I don't think that I can get the codes using the paper clip/jumper wire method because its an OBD 2. Unfortunately the ALDL wires come through the firewall and are bundled and sealed so it will take some doing to track down a bad wire some where. Thanks for the info guys
If you have the FSM, page 8A-50-3 explains how to troubleshoot/repair the DLC for Communication Errors.
Page 8D-4 instructs you on which pins to jumper on the DLC, then walks you through the sequence of button pushing to check the codes.
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Race Director
Joined: Apr 2000
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From: Texas
Unlike the 94 and 95 where you connect pins 4 & 12 on the ALDL (16 pin) connector to get the codes, the 96 does not work that way. I don’t believe you can get the codes using the on board diagnosis as on the 94 & 95. For the 96, an external scanner or code reader has to be used. This is because it has the OBD2 codes and software.
Another simple test is to run the CCM diagnostics via a jumper wire across the appropriate pins on the diagnostic link. This is outlined in the FSM. While that doesn't conclusively prove the link is working relative the PCM, it will tell you if the link is active or not.
You absolutely CAN get CCM diagnostics via the ALDL on a '96. The whole point of the above is that by testing to see if the CCM diagnostics work, you prove the ground wire to the ALDL is good. That narrows the troubleshooting to just the PCM ALDL wiring.
Race Director
Joined: Apr 2000
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From: Texas
Not true, 96GS#007 is correct - you can pin the DLC (Data Link Connector) to obtain/reset the codes like any earlier C4.
If you have the FSM, page 8A-50-3 explains how to troubleshoot/repair the DLC for Communication Errors.
Page 8D-4 instructs you on which pins to jumper on the DLC, then walks you through the sequence of button pushing to check the codes.
If you have the FSM, page 8A-50-3 explains how to troubleshoot/repair the DLC for Communication Errors.
Page 8D-4 instructs you on which pins to jumper on the DLC, then walks you through the sequence of button pushing to check the codes.
Why can't OBD II codes be displayed on a '96?....
OBD II has four characters...P for Powertrain Control Module...and the three digit code...300...for the error, in this case "Random Misfire". The C4 speedo can only display three characters, not four characters. As a result it can't display the PCM codes on the '96 cars.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
What would be done to get at the CCM data?
Is this the procedure for a 96. There is no mention to connect any pins on the ALDL connector (For the 94 & 95 it would be 4 & 12).
Is this corect?
1996 to 2004 Corvette (OBD II):
Turn IGN ON, ENG OFF.
ON DIC, Press RESET button to clear any warning messages.
Press and hold OPTIONS.
While holding OPTIONS, press FUEL four times within 10 sec.
Go into an AUTOMATIC mode to shows all parameters: PCM-TCS-RTD-BCM-IPC-RADIO-HVAC-LDCM-RDCM-SCM-RFA. If there are no problems, you will see "NO MORE CODES" on the ICP display.
The computer displays two kinds of codes, CURRENT and HISTORY, designated "C" or "H". A CURRENT code indicates a malfunction is present in the system whose module is displaying data. A HISTORY code indicates a past problem.
When the screen displays MANUAL DIAGNOSTICS, select the desired module by pressing the OPTIONS button to go forward or the TRIP button to go back. Press GAUGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase or CLEAR codes, press RESET.
Is this the procedure for a 96. There is no mention to connect any pins on the ALDL connector (For the 94 & 95 it would be 4 & 12).
Is this corect?
1996 to 2004 Corvette (OBD II):
Turn IGN ON, ENG OFF.
ON DIC, Press RESET button to clear any warning messages.
Press and hold OPTIONS.
While holding OPTIONS, press FUEL four times within 10 sec.
Go into an AUTOMATIC mode to shows all parameters: PCM-TCS-RTD-BCM-IPC-RADIO-HVAC-LDCM-RDCM-SCM-RFA. If there are no problems, you will see "NO MORE CODES" on the ICP display.
The computer displays two kinds of codes, CURRENT and HISTORY, designated "C" or "H". A CURRENT code indicates a malfunction is present in the system whose module is displaying data. A HISTORY code indicates a past problem.
When the screen displays MANUAL DIAGNOSTICS, select the desired module by pressing the OPTIONS button to go forward or the TRIP button to go back. Press GAUGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase or CLEAR codes, press RESET.
Thread Starter
Drifting
Joined: Feb 2009
Posts: 1,302
Likes: 2
From: colchester CT
Not true, 96GS#007 is correct - you can pin the DLC (Data Link Connector) to obtain/reset the codes like any earlier C4.
If you have the FSM, page 8A-50-3 explains how to troubleshoot/repair the DLC for Communication Errors.
Page 8D-4 instructs you on which pins to jumper on the DLC, then walks you through the sequence of button pushing to check the codes.
If you have the FSM, page 8A-50-3 explains how to troubleshoot/repair the DLC for Communication Errors.
Page 8D-4 instructs you on which pins to jumper on the DLC, then walks you through the sequence of button pushing to check the codes.
Thread Starter
Drifting
Joined: Feb 2009
Posts: 1,302
Likes: 2
From: colchester CT
Re-read my words with red bold and underline added to the important points...
Another simple test is to run the CCM diagnostics via a jumper wire across the appropriate pins on the diagnostic link. This is outlined in the FSM. While that doesn't conclusively prove the link is working relative the PCM, it will tell you if the link is active or not.
You absolutely CAN get CCM diagnostics via the ALDL on a '96. The whole point of the above is that by testing to see if the CCM diagnostics work, you prove the ground wire to the ALDL is good. That narrows the troubleshooting to just the PCM ALDL wiring.
Another simple test is to run the CCM diagnostics via a jumper wire across the appropriate pins on the diagnostic link. This is outlined in the FSM. While that doesn't conclusively prove the link is working relative the PCM, it will tell you if the link is active or not.
You absolutely CAN get CCM diagnostics via the ALDL on a '96. The whole point of the above is that by testing to see if the CCM diagnostics work, you prove the ground wire to the ALDL is good. That narrows the troubleshooting to just the PCM ALDL wiring.
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,008
From: Texas
What would be done to get at the CCM data?
Is this the procedure for a 96. There is no mention to connect any pins on the ALDL connector (For the 94 & 95 it would be 4 & 12).
Is this corect?
1996 to 2004 Corvette (OBD II):
Turn IGN ON, ENG OFF.
ON DIC, Press RESET button to clear any warning messages.
Press and hold OPTIONS.
While holding OPTIONS, press FUEL four times within 10 sec.
Go into an AUTOMATIC mode to shows all parameters: PCM-TCS-RTD-BCM-IPC-RADIO-HVAC-LDCM-RDCM-SCM-RFA. If there are no problems, you will see "NO MORE CODES" on the ICP display.
The computer displays two kinds of codes, CURRENT and HISTORY, designated "C" or "H". A CURRENT code indicates a malfunction is present in the system whose module is displaying data. A HISTORY code indicates a past problem.
When the screen displays MANUAL DIAGNOSTICS, select the desired module by pressing the OPTIONS button to go forward or the TRIP button to go back. Press GAUGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase or CLEAR codes, press RESET.
Is this the procedure for a 96. There is no mention to connect any pins on the ALDL connector (For the 94 & 95 it would be 4 & 12).
Is this corect?
1996 to 2004 Corvette (OBD II):
Turn IGN ON, ENG OFF.
ON DIC, Press RESET button to clear any warning messages.
Press and hold OPTIONS.
While holding OPTIONS, press FUEL four times within 10 sec.
Go into an AUTOMATIC mode to shows all parameters: PCM-TCS-RTD-BCM-IPC-RADIO-HVAC-LDCM-RDCM-SCM-RFA. If there are no problems, you will see "NO MORE CODES" on the ICP display.
The computer displays two kinds of codes, CURRENT and HISTORY, designated "C" or "H". A CURRENT code indicates a malfunction is present in the system whose module is displaying data. A HISTORY code indicates a past problem.
When the screen displays MANUAL DIAGNOSTICS, select the desired module by pressing the OPTIONS button to go forward or the TRIP button to go back. Press GAUGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase or CLEAR codes, press RESET.
I'm not at home, so I can't look up the specific pages. For the CCM, I doubt the pins that you jumper were changed from the '94/'95 cars.
Burning Brakes
Joined: Nov 2010
Posts: 855
Likes: 36
From: Crystal Springs MS
You can do this for all codes except the PCM. OBD I codes were three characters...C or H for "Current" or "History" and the two digit code. The FSM is in error in this regard.
Why can't OBD II codes be displayed on a '96?....
OBD II has four characters...P for Powertrain Control Module...and the three digit code...300...for the error, in this case "Random Misfire". The C4 speedo can only display three characters, not four characters. As a result it can't display the PCM codes on the '96 cars.
Why can't OBD II codes be displayed on a '96?....
OBD II has four characters...P for Powertrain Control Module...and the three digit code...300...for the error, in this case "Random Misfire". The C4 speedo can only display three characters, not four characters. As a result it can't display the PCM codes on the '96 cars.
Burning Brakes
Joined: Nov 2010
Posts: 855
Likes: 36
From: Crystal Springs MS
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,008
From: Texas
No, you CAN do the PCM, it's Mode 4 - the Mode# tells you which system it is (1 for CCM, 4 for PCM, 7 for RTD if equipped, 9 for ABS, A for SIR). The speedo readout then gives you the 3-digit Trouble Code associated with that mode. Section 8D in the FSM gives a very good description of it. I did it dozens of times until I finally broke down and got a OBD2 scanner.
Btw...I should have stated the codes are actually five characters long, not four. Pxxxx, such as P0133 – Bank 1 HO2S #1 Circuit Slow Response or P1133 – Bank 1 HO2S #1 Circuit Not Enough Switches. I would love to see how your three digit speedo differentiates between two very similar four digit codes.
Thread Starter
Drifting
Joined: Feb 2009
Posts: 1,302
Likes: 2
From: colchester CT
Okay, I am really confused now. anyone in CT who wants to make some money? I have all kinds of projects going on. I was just getting ready to put in a new steering rack when the engine light came on
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
You best bet is studying the FSM. Make sure you have power and ground at the DLC for starters. Then find a wiring diagram of the communications lines between the modules. Comm. problems are always fun, even for a good professional mechanic. If I was a lot closer I'd drop by to help.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
Nope. That works for '97 & up. Looks like you have a Chiltons, Haynes, or some other book. You need the GM (produced by Helms) Factory Service Manual.
I'm not at home, so I can't look up the specific pages. For the CCM, I doubt the pins that you jumper were changed from the '94/'95 cars.
I'm not at home, so I can't look up the specific pages. For the CCM, I doubt the pins that you jumper were changed from the '94/'95 cars.
Came right out of a Forum thread that I trusted.
I will say that pulling codes from a 96 has been confusing as I have heard everything from you can't, to you can.
If I had the FSMs for a 96 I would know for sure.
How about posting a brief procedure.
