Great stuff! I'll hook my multimeter between the ground wire and frame while checking continuity... see if that might be the issue. I'll also check power at the computer. Thank you much

 

I did try the test light method with no luck. Today, I did check the continuity between the single red/white wire and the negative battery post and the frame... no continuity at all. I'll fiddle around with ensuring the yellow wire, to the computer, has power this weekend as well as trying the code reader with the single wire grounded to the negative battery post again (my first attempt didn't get any codes). Good news, though, I drove my rig up the nearby hill and it had more power than ever. It idles perfectly and doesn't blow black smoke. I'll check my fuel economy and see if that has improved. Thank you so very much Jackietreehorn for all the resources... you've given me much info to work with.

 

You're welcome. and this might be your problem. Connect that jumper andthe code reader straight to the negative battery.

 

The red and white wire attached to the grey connector is not a ground wire and will not have continuity to ground. Measure this wire (Self-Test IN) and there should be 5vdc with the key on.

The signal return (SIG-RTN) wire is connected to ground via the ECA (Engine Computer), so check that wire for continuity to ground.

Check your new code reader to be sure the blades are not pushing in when you attach to the Self-Test connectors.

Check the ground wires to your ECA when you get the chance.

 

Copy, I will hook my multimeter up and try voltage from the red/white wire. Thank you all for the info as I'm learning more about this system every day.

 

1986 EVTM - Gary's Garagemahal (the Bullnose bible)

This might help you as well...