Ignition Timing Question

Today I was looking at checking / adjusting the ignition timing on my
1995 EG Honda Civic (1.5L D15B7)
In the Honda Manual it states that you need to "jump" the service check
connector when adjusting the ignition timing. Can someone tell me why
this needs to be done and if it makes a difference?
Regards,
Michael.

 

When you set the timing, you are setting the "base" timing. This is the
datum from which all other adjustments are made.

Jumping that connector prevents the ECU from being able to alter base
timing while you set it.

 

the ecu constantly adjusts the timing based on data from various
sensors. this makes it hard/impossible to set the base timing. jumping
the service check connector tells the ecu to /not/ make any adjustments
thereby allowing timing to be set. an unbent paperclip is a great tool
for this job - fits perfectly.

 

Thanks for the info, thats answered my question.
Regards,
Michael.