This is the Diagnostic port pin identification list:
Pin Terminal # Terminal Description
1------ TD TD Signal
2------ - Not occupied
3------ - Not occupied
4------ - Not occupied
5------ - Not occupied
6------ - Not occupied
7------ SI Service Interval Reset
8------ - Not occupied
9------ - Not occupied
10----- - Not occupied
11----- - Not occupied
12----- 61 (D+) Generator Charge Indicator
13----- - Not occupied
14----- 30 Voltage; Hot At All Times
15----- RXD Diagnostic Data Link
16----- 15S Voltage Ignition Switch in Run
17----- - Not occupied
18----- PGSP Programming Line
19----- 31 Ground
20----- TXD Diagnostic Data Link