on their corvette and it doesn't go into diagnostics mode?

On my '85, I have to use the 10k Ohm Resistor to start the data stream to flow, and the car goes into diagnostic mode.

I wonder if there is a way to make it NOT go into diagnostics mode..

 

I was also getting lonely here waiting for this Mojo! Check out "more torque when I connect Moates ALDL tool...." elsewhere but you might already be watching that one.

 

In the topic 1986Z51 referenced, I added a link to a thirdgen.org post where someone (I think RBob) stated the field $23 could be changed to 0 to eliminated spark advance on the 165 ecm. You might want to see if it works on the 6870 as well, or maybe contact tunercat (thats what you use, right?) and maybe they can add it to your ECU file. There was somone in my link that added it to some 165 ECU files, so maybe it can be done to the 6870.

 

I just got done working this issue on my '86 with '165 ECM. Yes, the 10K resistor puts the car into the 'diagnostic' mode along with outputting the default 160 baud data stream. My experience is that enabling the 8192 baud ECM mode (by sending a request for the 8192 baud mode through Pin E) also kicks the car out of diagnostic mode (so once the 8192 baud mode is enabled then removing the 10K resistor is moot -- you can remove it and the data keeps coming). This was with Moates software and I couldn't get it to work with Datamaster after trying it a few times.

I've been wrestling with a MAX232 based ALDL cable I bought and was relegated to the diagnostic/160baud mode using WinALDL and was unable to use Moates, Datamaster, etc. After **some** digging I earned that you have to have the right circuit to enable the 8192 mode on a '165 ECM. Some of this info was in a CF archive:

http://forums.corvetteforum.com/arch.../t-228161.html

The MAX232 device doesn't work since the ALCL connector Pin 5 is a bi-directional 5V interface (like RS-485) and NOT RS-232. The RS-232 device has too high a source resistance to transmit OVER the incoming 160 baud data and initiate the 8192 baud mode. The MAX232 circuit CAN be modified with a transistor switch at the Tx output to ALCL Pin 5. I built a two-transistor interface cable (thanks to forum member who was sucessfully scanning his '165) instead of modifying the MAX232 circuit however.

I was determined to be able to scan my '165 in 'normal' mode cause I'm interested in burning my own chips without any guesswork as far as how the engine/ECM is actually running. Getting out of 'diagnostic' mode was key, with fast data at 8192 as a nice bonus. Hope this info helps other having problems scanning '165 ECMs.