Can't read diag codes using test light on 86 2.9

[85RangerST]

my ranger has flat spot on idle and jerks at very low engine speed. My friend hooked his scanner up and it errors out with "engine not resonding". I go to the EEC-IV Diagnostics located in the tech lib here on TRS and find info to use test light w/out scanner and still not able to scan.

The test light stays on and doesn't blink...below are the steps I made:

1. Warm up eng and turn off
2. hookup test light to STO and +12v
3. connect STI to SIG Rtn
4. turn key on w/out cranking eng.

Maybe someone knows why i'm having this problem or can provide info on what to check or do next. This engine is now swapped into my 85 Ranger and has had this problem since the swap...not sure if it worked correctly in the 86 truck it came from.

Thanks

 

[85RangerST]

Sorry everyone...I must have followed the instructions incorrectly yesterday. I was able to scan using test light without incident just a few minutes ago. I read 2 codes, 63 and 31 while doing KOEO.

Regards,
David