how to ground ALDL connector

i need someone to please tell me how to ground the ALDL connector i have been told i need to do this before i adjust the minimum idle speed
thanks in advance

Unless you have a carb and not TBI the ecm will handle the idle speed. Even on your 87. The aldl is for diagnostics on your truck, not programming. I think you're confused as to what your friend told you. You disconnect the ECM from the distributor for timing. Not ground the aldl.

On some model TBs there was an adjustment for min idle speed.
There is a special tool to block off the air port to the IAC and then you can turn the min. idle screw.
This is a base adjustment, the PCM controls the idle speed thru the IAC valve position.