UNABLE TO SCAN ENGINE CODES

[GOFAST]

I have a '95 with 9000 miles. The "Service Engine Soon" light comes on intermittantly, stays on for a few seconds, and then goes out. I have tried to capture the stored codes using a scanner but the scanner has been unable to connect/communicate with the ECM.

Two different scanners have been unable to link/communicate with the host but both work fine on my other car. My '95 has a OCB2 connector. Any idea as to why the scanners can't connect with the ECM?

Thanks.

[VetteMed]

95 has an OBDII connector, but is OBDI. You can't use an OBDII scan tool to talk to the ECM. You need an OBDI scan tool with the OBDII connector.

[scottfab]

I have a '95 with 9000 miles. The "Service Engine Soon" light comes on intermittantly, stays on for a few seconds, and then goes out. I have tried to capture the stored codes using a scanner but the scanner has been unable to connect/communicate with the ECM.

Two different scanners have been unable to link/communicate with the host but both work fine on my other car. My '95 has a OCB2 connector. Any idea as to why the scanners can't connect with the ECM?

Thanks.

Does the scanner lit say it works with a 95 ?

[GOFAST]

My scanner is both OBDI and OBDII compatable. How do I assure the scanner is in OBDI mode with the OBDII connector?

Thanks.

[ghlkal]

I know the 95 is a hybrid with OBDI but an OBDII connector.

Can you do the earlier OBDI "trick" of connecting pin "12" to pin "4" (I think those are the right connectors on a 95) and turn the ignition on and have the dash display CCM and ECM parameters?
http://www.zr1.net/forum/showthread.php?t=17846

[scottfab]

My scanner is both OBDI and OBDII compatable. How do I assure the scanner is in OBDI mode with the OBDII connector?

Thanks.

If it's both you should be in.
What scanner did you get?
Does it have a manual online?

[tomtom72]

I have a snap-on MT2500, it's an old one too. On it the software cartridge you use is what enables the "communication link" to happen. Sometimes I forget and leave in the OBDI stuff when I plug it into my 08 Cobalt.:o

[GOLDCYLON]

Referring to whats already been posted above. The 95 is indeed an OBDI and OBDII Hybrid. MY 96 was the first OBDII corvette. I think Andrew said that as well.

With this in mind a OBD1/OBD2 scanner should work but you will need either the correct cable, the correct cartridge or the correct mode to be set on your reader/scanner

So lets start over again here. What model scanner or Code reader are you running. Some of us use multiple models and maybe able to help with the setup. I use a Tech 1A or an Auto X-Ray 6000

[GOLDCYLON]

Based on what you've posted I found what I think is the manual for it at:

http://buy1.snapon.com/products/diagnostics/downloads/manuals/AsianImportVCS%28EAZ0025B02CRevA%29/06%20Operations.pdf


Does this look like the manual you have?

One quick point of isolation you can do is take the car to an Autozone or O'Rileys and get them to hook up one of theirs to see if the port on you car is ok. Probably not necessary but would guarantee pursuing the MT2500 unit is not wasted. Who knows maybe the port got damages when someone tried shorting some pins?


I do see some posts about updates for the MT2500 but it's not clear to me that you would need these.

Scott. Your confused. Tom has the Snap on Scanner. Not the OP. He has not identified the equipment he is running yet. Which IS part of the problem. GC

[GOLDCYLON]

So you're saying the manual I found is wrong? And he would not be using the MT2500 ? Or is there a module he's missing that works together with the MT2500 or wire harness, and therefore the manual I found is correct? You must know the snap-on scanner well?


Scott reread the post. The OP GOFAST has not identified either of his two scanner or readers.

Thats my point Tom is the one with a MT2500 scanner. Your link is for Toms model and not the OPs

Still confused?


You must know the snap-on scanner well?


As to this comment Scott why do you consistently feel it necessary to attempt to chide the membership in your posts?

No I do not know the snap on scanner well. As aready stated I know the AutoXray 6000 and the Tech 1-A well.

[scottfab]

Scott reread the post. The OP GOFAST has not identified either of his two scanner or readers.

Thats my point Tom is the one with a MT2500 scanner. Your link is for Toms model and not the OPs

Still confused?

no not now. "you're" correct I was reading the wrong post. My bad.
Thank you. I deleted my confused posts to clean up the tread.


As to this comment Scott why do you consistently feel it necessary to attempt to chide the membership in your posts?

No I do not know the snap on scanner well. As aready stated I know the AutoXray 6000 and the Tech 1-A well.

WOW! you took that as a dig? NOT AT ALLLLLLLLLLLL
It was an assumption that I knew nothing of the Snap on scanner.
Please reread!

[GOLDCYLON]

no not now. "you're" correct I was reading the wrong post. My bad.
Thank you. I deleted my confused posts to clean up the tread.



WOW! you took that as a dig? NOT AT ALLLLLLLLLLLL
It was an assumption that I knew nothing of the Snap on scanner.
Please reread!


Thanks for the cleanup. Ok thanks for that clarification. Now back to the OP what Scanning/reading tools are you using?

[scottfab]

Thanks for the cleanup. Ok thanks for that clarification. Now back to the OP what Scanning/reading tools are you using?

GOFAST apparently you are "OP".
Not sure if you were but I was confused about what an "OP" was.

[VetteMed]

So what is the best scanner on the market for our cars?

Tech 1 or Tech 1A, or Mastertech (does everything the Tech 1/1A can do, and more).

[GOFAST]

One of the scanners was a SNAP-ON but I'll have to check the model. I'll have to check the make on the other as well.

[GOLDCYLON]

GOFAST apparently you are "OP".
Not sure if you were but I was confused about what an "OP" was.

OP='s Original Poster. GC

[GOLDCYLON]

So what is the best scanner on the market for our cars?


For all the functionality that GM intended in the Atari Generation. The Tech 1-A. Or Mastertech which is the same device.

A lot of the newer scanners will do 90% of what the GM scanners will do but not everything. GC

[GOLDCYLON]

How about TS........for Thread Starter :D

I have found that the Tech 1A main electronics board costs $500 to replace from Vetronix Corporation. Vetronix Corporation will not send you a replacement main electronics board but rather you have to send your Tech 1A to them for a $65 service charge just to look at it. I have run into two Tech 1As within the last month each of which had a bad main electronics board.


Always possible Cliff these units are becoming long in the tooth like thier owners lol. GC

[scottfab]

So what is the best scanner on the market for our cars?

Don't know about best but I use Diacom data logger (works on a laptop with a special adapter and ODBII connector) and a Dyno-Scan by Auterra.
With these I get codes and data logging. A very handy feature for analysis of problems instead of shot gunning parts. These are great but cannot perform the "active diagnostics".

For active diagnostics I use the car's built in tests. The 90 has many that were left out of subsequent MYs. To access these I made a ODBII connector that simply has a rotary selector that grounds one of about 5 pins at a time. What gets grounded is all in the manual.
(ADDED LATER - I also have a CanOBD2 scanner by INNOVA.

[QB93Z]

To go back to the original question about codes. I have had situations where the Service Engine Soon light comes on and there are no codes stored.

One condition where I have seen this is when a primary injector had a broken wire. No fuel to one cylinder caused a lean condition on that side and the SES light would come on and go out but I wasn't getting a code.

Another situation that I never identified, but I suspect was failing injectors was that the SES light would occasionally come on after a full throttle acceleration, would stay on until the engine was turned off and restarted. The SES would not return after the restart, and there were no codes set. I saw this several time over the years with my 1993.

GOFAST, you may be reading the codes correctly, but there aren't any there.

I recommend that the protracted discussion about code readers and data loggers be taken to a separate thread and we try to help GOFAST with his engine performance question.

Jim

[tomtom72]

Just a note about the operational capability concerning different make scanners:

The reason most of us look for the Vertronix ( now owned by Bosch? ) Tech 1 or Tech 1A machines is that they were specifically intended for use at GM dealerships. Now, the most important part of the tool is the software library that came with it! If you look at the DTC diagnostic flow charts in our FSM's you can see where the Tech machines & their software do certain "functional tests".

The real key thing is the software and not necessarily the scanner itself. Trouble is the GM s/ware is copy-righted. The Vertronix boys had the corner on the OBDI GM software because it was awarded the GM contract.

Even my snap-on software for GM cars is abridged and will not do any of the "functional tests" listed in the 90 FSM that do not directly relate to emission's control / engine management systems.

I do believe that with OBDII equipped cars there was an effort to standardize software even further to include "safety items", but I'm not too sure how far that goes. Stuff like ABS, EBFD, EVSC, T/C, all may be included with the 'generic' software in OBDII format. I think on our cars, if my snap-on ABS software is any indication of OBDI copy-right generosity, I can not use the cartridge to bleed the ABS pump.....or at least I can't seem to figure it out.

The moral of all my hot air is that for our ZR-1's, if you want a full function scanner you need the Tech series with all the proprietary software GM wrote or you have to do without the non-emissions functionality tests.

:o Sorry to be so long-winded but this is how I understand the scanner software situation to be and I just wanted to make the point about proprietary software vs generic emissions software.

:cheers:
Tom

[VetteMed]

Just a note about the operational capability concerning different make scanners:

... snipped...

The moral of all my hot air is that for our ZR-1's, if you want a full function scanner you need the Tech series with all the proprietary software GM wrote or you have to do without the non-emissions functionality tests.

:o Sorry to be so long-winded but this is how I understand the scanner software situation to be and I just wanted to make the point about proprietary software vs generic emissions software.

:cheers:
Tom

Tom, I agree, but it's important not to overlook the fact that the processor and software is exactly the same in the Mastertech. The Mastertech goes a step above with an additional processor but definitely has the same abilities as the Tech 1.

[GOLDCYLON]

Just a note about the operational capability concerning different make scanners:

The reason most of us look for the Vertronix ( now owned by Bosch? ) Tech 1 or Tech 1A machines is that they were specifically intended for use at GM dealerships. Now, the most important part of the tool is the software library that came with it! If you look at the DTC diagnostic flow charts in our FSM's you can see where the Tech machines & their software do certain "functional tests".

The real key thing is the software and not necessarily the scanner itself. Trouble is the GM s/ware is copy-righted. The Vertronix boys had the corner on the OBDI GM software because it was awarded the GM contract.

Even my snap-on software for GM cars is abridged and will not do any of the "functional tests" listed in the 90 FSM that do not directly relate to emission's control / engine management systems.

I do believe that with OBDII equipped cars there was an effort to standardize software even further to include "safety items", but I'm not too sure how far that goes. Stuff like ABS, EBFD, EVSC, T/C, all may be included with the 'generic' software in OBDII format. I think on our cars, if my snap-on ABS software is any indication of OBDI copy-right generosity, I can not use the cartridge to bleed the ABS pump.....or at least I can't seem to figure it out.

The moral of all my hot air is that for our ZR-1's, if you want a full function scanner you need the Tech series with all the proprietary software GM wrote or you have to do without the non-emissions functionality tests.

:o Sorry to be so long-winded but this is how I understand the scanner software situation to be and I just wanted to make the point about proprietary software vs generic emissions software.

:cheers:
Tom

Yep this is why I said only 90% functionality vs other scanners. The Tech-1A can perform a lot of the tests only meant for the eyes of the Trained GM Master Techs. You need one of these in your tool box if you plan on staying in the hobby for a while.

Hot Air Tom?? Sorry sounds like valuable technical advise to me.

[GOLDCYLON]

To go back to the original question about codes. I have had situations where the Service Engine Soon light comes on and there are no codes stored.

One condition where I have seen this is when a primary injector had a broken wire. No fuel to one cylinder caused a lean condition on that side and the SES light would come on and go out but I wasn't getting a code.

Another situation that I never identified, but I suspect was failing injectors was that the SES light would occasionally come on after a full throttle acceleration, would stay on until the engine was turned off and restarted. The SES would not return after the restart, and there were no codes set. I saw this several time over the years with my 1993.

GOFAST, you may be reading the codes correctly, but there aren't any there.

I recommend that the protracted discussion about code readers and data loggers be taken to a separate thread and we try to help GOFAST with his engine performance question.

Jim


I’ve seen this condition that would not set a hard code fault on any reader/scanner as well in the secondary system. A slow or weak vacuum secondary actuator will cause a momentary SES to light and not store a hard code and there are MANY pieces from that system that can cause the same problem. Normally this is seen during or after hard acceleration.
Lots of possibilities. GC

[scottfab]

................

I recommend that the protracted discussion about code readers and data loggers be taken to a separate thread and we try to help GOFAST with his engine performance question.

I agree this needs a new thread. And it should probably be a "Solution" thread to help others in a general way.