OK. Got my two transistor interface cable built and it works *perfectly* on my 1994 Chevy pickup. Now, when I connect to my 91 Z28, the communications are established, I get what seems to be intermittent ALDL loss of communication.

I'm currently using the DataMaster software in the trial period and I get a beep and the ALDL communication indicator lights up red. This seems to happen randomly, but relatively frequently (like once or twice a minute) and lasts just a second or two at a time. As stated earlier, it works without this problem on my pickup. And yes, I'm using the correct DataMaster for each vehicle.

Any thoughts as to what sparks to chase? There are no faults in ECM according DataMaster and SES flash codes - all I get is the code 12 when I do the flash codes.

Thanks,