Continued Issue
Thread Starter
Drifting
Joined: Nov 2018
Posts: 1,782
Likes: 578
From: Mays Landing, NJ
Continued Issue
My 95 is still suffering intermittent misfire. It will run well for miles and then get a miss like a cylinder is not firing, but that issue resolves itself after a short time. The check engine light has come on a few times and goes off on its own. I can't pull code to get a starting point because the scanner gets to the second engine module and stops due to an error in reading it.
Because of that the best I can assume is it is losing communications with something in the second module. Any of you have insight on what the second module may be trying to read from? Since it runs and idles nicely at all engine temps in open and closed modes and I can't pull codes that could help me I'm a bit lost as to why I'm getting the misfire. I.ve searched and can't find why second module is getting a error. Any thoughts ???
Because of that the best I can assume is it is losing communications with something in the second module. Any of you have insight on what the second module may be trying to read from? Since it runs and idles nicely at all engine temps in open and closed modes and I can't pull codes that could help me I'm a bit lost as to why I'm getting the misfire. I.ve searched and can't find why second module is getting a error. Any thoughts ???
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
The second module is the module 4, the PCM. Use the on board diagnostics to pull the codes for the PCM. You short pins 4 and 12 on the ALDL connector. If you don’t know how to do this you need some additional information on the procedure and the codes.
Your scanner might have a problem but don't forget, the system is OBD1 and if you're using a OBD2 scanner it is not going to work to pull any codes at all.
Just as a guess I might try replacing the ICM which causes similar problem.
I would look at the wires in the dark to see if there is any sparking to ground.
I would not yet look at the opti, way too soon, except if there is an opti code.
Your scanner might have a problem but don't forget, the system is OBD1 and if you're using a OBD2 scanner it is not going to work to pull any codes at all.
Just as a guess I might try replacing the ICM which causes similar problem.
I would look at the wires in the dark to see if there is any sparking to ground.
I would not yet look at the opti, way too soon, except if there is an opti code.
Thread Starter
Drifting
Joined: Nov 2018
Posts: 1,782
Likes: 578
From: Mays Landing, NJ
I'm using an Actron 9690 that reads OBD 1 and OBD2. and I have used for my 91 and now the 95. Always read both perfectly with never an error. I hate to start throwing parts at it. Normally I'm not a "fix in a bottle" type of person, but put on a bottle of Techron injector cleaner to see if I notice any changes. Happen to drive about 20 miles today and didn't miss at all. The random nature of the miss just makes it tougher to figure out.
I am going to follow your advice to look for any spark issues at night.
I am going to follow your advice to look for any spark issues at night.
Heel & Toe
Joined: Jul 2020
Posts: 15
Likes: 2
From: NC
https://www.corvetteforum.com/forums...ps-w-pics.html
See Post 18 if your Scanner won't read your codes..
See Post 18 if your Scanner won't read your codes..
Heel & Toe
Joined: Dec 2021
Posts: 18
Likes: 5
From: Wisconsin
You have an OBD 2 connector and a OBD 1 system. . Not sure what snap on scanners hook up and display but a Mastertech scanner has an interface connector to explore the OBD 1 system with the OBD2 diagnostic link
Either way OBD 1 systems do not see a fault code on intermittent misfires
Either way OBD 1 systems do not see a fault code on intermittent misfires
Thread Starter
Drifting
Joined: Nov 2018
Posts: 1,782
Likes: 578
From: Mays Landing, NJ
https://www.corvetteforum.com/forums...ps-w-pics.html
See Post 18 if your Scanner won't read your codes..
See Post 18 if your Scanner won't read your codes..
Thread Starter
Drifting
Joined: Nov 2018
Posts: 1,782
Likes: 578
From: Mays Landing, NJ
You have an OBD 2 connector and a OBD 1 system. . Not sure what snap on scanners hook up and display but a Mastertech scanner has an interface connector to explore the OBD 1 system with the OBD2 diagnostic link
Either way OBD 1 systems do not see a fault code on intermittent misfires
Either way OBD 1 systems do not see a fault code on intermittent misfires
Today I drove it to work and ran perfect without the SES light coming on at all. That is, until I drove into my neighborhood when it stated to miss but went back to normal when I pulled up to the house.
Heel & Toe
Joined: Jul 2020
Posts: 15
Likes: 2
From: NC
Interested in your problems for multiple reasons. 1) I have a 94 with a OBD II connector and a OBD I system. After reading your post, I looked into buying an Actron 9690 as a possible replacement to my Actron 9180 because the 9690 covers the OBD I systems of my year . Unfortunately I could not find any for sale. Not sure if it is a supply chain issue or that model is being phased out. 2) I have a misfire on my car that is permanent but my SES light never comes on so I can't even get to the point where you are in trying to find a starting point for your diagnosis. If you have successfully utilized your 9690 in the past on your 95 with no communication issues in the second module, perhaps your issue is in your PCM....I hope that is not the case. Good luck with your issue..
I thought the paperclip method might give you access to the code to aid in your diagnosis...I do understand your position having utilized the 9690 successfully in the past.
FYI...I found this to be well worth the money to avoid the use of the paperclip...just connected the wires on the plug for pins 4 and 12 and you have a permanent paperclip that you can plug in with out crawling under your dash...:-)
I thought the paperclip method might give you access to the code to aid in your diagnosis...I do understand your position having utilized the 9690 successfully in the past.
FYI...I found this to be well worth the money to avoid the use of the paperclip...just connected the wires on the plug for pins 4 and 12 and you have a permanent paperclip that you can plug in with out crawling under your dash...:-)
Last edited by TJBlueVette; Jul 6, 2022 at 06:34 AM. Reason: Adding info
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Thread Starter
Drifting
Joined: Nov 2018
Posts: 1,782
Likes: 578
From: Mays Landing, NJ
https://www.amazon.com/gp/product/B0...0?ie=UTF8&th=1
FYI...I found this to be well worth the money to avoid the use of the paperclip...just connected the wires on the plug for pins 4 and 12 and you have a permanent paperclip that you can plug in with out crawling under your dash...:-)
I've had the Actron for about 5 years and never had a problem reading both corvettes and my OBD 2 vehicles. Although I'm still thinking that if module 2 had a communication issue with the scanner that same issue will occur with the "paperclip method".
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
I have never investigated this myself but how many other cars use a 16 pin connector using OBD1. Most that I know of use the 12 pin connector. The data may not come out of the same pins. This I think may be the problem as why a scanner that can do OBD1 just can't get the data due to a connection issue.
Heel & Toe
Joined: Jul 2020
Posts: 15
Likes: 2
From: NC
I just spoke with a Tech at Actron regarding that very issue....he assured me that the machine could tell it was probing an ODB I system by the data from the pins it was seeing. He mentioned that you would have to use the cigarette power adapter as ODB I did not have a power pin to the unit as does an ODB II system. This was news to me as I have always used the paper clip method prior to this on all my previous ODB I vehicles...
BTW...there are no Actron 9690's available anywhere in the US right now...they were not sure if this model is going end of life but confirmed it is the only ODB II/I model in their stable. Bosch makes an ODB II/I model # 1300 that I believe is the exact same unit as the Actron which apparently is owned by Bosch. I just ordered one of these.
BTW...there are no Actron 9690's available anywhere in the US right now...they were not sure if this model is going end of life but confirmed it is the only ODB II/I model in their stable. Bosch makes an ODB II/I model # 1300 that I believe is the exact same unit as the Actron which apparently is owned by Bosch. I just ordered one of these.
Last edited by TJBlueVette; Jul 11, 2022 at 08:41 AM.
Thread Starter
Drifting
Joined: Nov 2018
Posts: 1,782
Likes: 578
From: Mays Landing, NJ
Actually, do not have to use the cigarette adapter on the 95 because one of the pins does supply 12 volt, but If i recall had to use it on the 91.. And the unit does have internal battery, but that drains very quickly.
Heel & Toe
Joined: Jul 2020
Posts: 15
Likes: 2
From: NC
Appreciate the feedback..
Just received my Bosch ODB1300...I believe it is the same machine as the Actron 9690 but I was able to find one of these.
FYI..plugged it in and ran diagnostics..it errored on the second module. Did not have any codes in mod 1 so don't know if it would have recognized those..
Just received my Bosch ODB1300...I believe it is the same machine as the Actron 9690 but I was able to find one of these.
FYI..plugged it in and ran diagnostics..it errored on the second module. Did not have any codes in mod 1 so don't know if it would have recognized those..
Last edited by TJBlueVette; Jul 11, 2022 at 08:41 AM.