Micro Starter Relay (Replacement for OE 31522-00A) — 12V, 5-pin SPDT, 15A, built-in flyback diode, fully potted housing. Direct plug-in to the relay block on many Twin Cam models.
Specs: 12V system, 15A contact rating; approx. size 7/8" × 9/16" × 1"; socket-mount, 5 terminals; diode suppresses voltage spikes.
Function: Routes current to the starter solenoid; the integrated diode protects the ECM and other electronics when the coil is de-energized.
Install location: Typically in the fuse/relay block under the seat or behind the left side cover; confirm cavity ID in your service manual.
Cross-reference: Replaces OE 31522-00A and is compatible with 31522-00/31522-00B/31522-00C; industry refs MC-RLY5 / DS-325849 / MID-16406.
Common symptoms resolved: No-crank with good battery, intermittent click at the starter, repeated relay failure where a built-in diode is specified.
Package includes: 1× micro starter relay (no instructions; reuse OEM carrier/cover).
Compatibility summary (abbrev.): Big-Twin Softail (selected 2000–2014), Dyna (2000–2014), Touring ranges (2000–2013 depending on model), and VRSC V-Rod (2002–2005). Always match by OE number and year/model before purchase.
Complementary items: Many models also use a system/ECM relay (31511-01A/31511-01B, MC-RLY6). For hard-start due to worn solenoid contacts, a starter-solenoid repair kit (31604-06, select 2007–2017 Big Twins) can be used.
Note: This is an aftermarket replacement component. Vehicle names are used strictly to indicate compatibility.