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25 Circuit - Pro Series - Key In Dash – Grommet Firewall Pass-Through By Painless Performance

Made In USA
25 Circuit - Pro Series - Key In Dash – Grommet Firewall Pass-Through By Painless Performance

P/N 10412 $549.99
25 Circuit - Pro Series - Key In Dash – Grommet Firewall Pass-Through



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The ALL NEW Pro Series line by Painless 

The Painless Pro Series gives you everything you need to wire up your pro-touring or custom ride right the first time!  Ample length is provided for each circuit, providing you the freedom to route and hide your wiring how you choose. Once you’ve got the harness fit how you like it, included are over 25 GM factory style connectors found on most ‘60s to early ‘90s GM switches, allowing you to turn the Pro Series harness into a direct fit harness for your application. LED ATC bladed fuses get you away from the old hard-to-find glass fuses, and will light up if blown making troubleshooting a painless task. The 6 gauge charge wire and midi fuse (no more problematic fusible link!) will keep up with today’s high amperage alternators, and the provided front and rear ground harnesses making grounding your lighting circuits a breeze!  Provided with many GM connectors and terminal, insulated and non-insulated butt splices, heat shrink, grommets, cable ties, ground straps, and cable tie clips, the Pro Series brings a new meaning to truly Painless wiring and includes our lifetime guarantee.  


This harness features a grommet style firewall pass through with the fuse block mounted inside the vehicle on or near the firewall. The wires are pre-terminated using Packard factory crimping machines and utilize a grommet to pass through the firewall, keeping your wiring safe and protected from harsh metal edges. Each wire is extra length with up to 20’ of length to the front and over 25’ to the rear providing ample length for mounting your fuse block and freedom to route the wiring how you choose. After trimming to fit, utilize the provided terminals & connectors to terminate the ends.


This harness comes with adaptable open-ended ignition switch wiring and terminals, allowing you to adapt to any ignition switch you desire!  GM old style (3-3/4”) and new style (4-1/4”) turn signal switch connectors are included.


Included with the GM Pro Series harnesses is:

  • (4) H4 Headlight connectors- to support single (high/low) or dual headlights (separate high beams)
  • (2) Turn signal connectors- fits connectors found on factory GM hard wired turn signals
  • (4) Molded ¼ sockets for front & rear marker lights
  • (2) HEI distributor connectors (+ and Tach)
  • (2) Connectors for factor GM wiper motor
  • GM washer pump connector
  • Courtesy light sockets
  • GM headlight switch connector
  • GM dimmer switch connector
  • Gm brake switch connector
  • GM turn signal switch flat connectors (early & late)
  • GM ignition switch connectors*
  • Neutral Safety Switch connector (column mounted or factory floor shifter mounted)
  • Reverse Switch connector (column mounted or factory floor shifter mounted)
  • Braided ground straps (for body and core support to frame grounding, also includes (6) self-tapping ¼” screws for mounting)
  • Alternator bag kit with terminals, splices, resistor, diode to connect the alternator. (1) Connector for GM 10si alternator
  • Assortment of insulated and non-insulated splices, ring terminals, heat shrink, grommets, cable ties, and cable tie clips. 


* Only on GM keyed column harnesses


Full Circuit listing available on the specs tab!




WarningProp 65 Warning
Hazardous Material Warning

WARNING: This product can expose you to chemicals including lead which is known to the State of California to cause cancer or birth defects or other reproductive harm. For more information, visit

Link to P/N:
Year: Universal
Make: GM
Model: Universal
Engine: Any
Trans.: Any


23 Circuit Harnesses

Small and Compact Fuse Block utilizes 12 Fuses to Support 23 Total Circuits

25 Circuit Harnesses

Slightly Larger Fuse Block Adds Power Window and Power Lock Support.  18 Total Fuses Support 25 Total Circuits, giving more components their own dedicated circuit.

This harness includes circuits for:

  1. A/C & Heat
  2. Accessory (Fan Relay Activation, etc.)
  3. Backup Lights
  4. Brake Lights
  5. Charging
  6. Cigarette Lighter
  7. Dome / Courtesy Lights
  8. Electric Choke
  9. Electric Fuel Pump
  10. Emergency Flashers
  11. Fused Power Source
  12. Grounds – Front and Rear Lights
  13. Headlights
  14. Horn (Relay)
  15. Ignition Coil
  16. Instrument Panel Lighting and Gauges*
  17. Park / Marker Lights
  18. Power Door Locks
  19. Power Windows
  20. Radio/Clock (Constant and Switched)**
  21. Starting
  22. Tail Lights / License Plate Light
  23. Third Brake Light
  24. Turn Signals
  25. Wipers / Washer Pump


* Including Wires For;
Fuel Gauge
Oil Gauge
Temperature Gauge

** Includes

Amp Activation Wire