{"product_id":"h104-indicator-light-adapter-harness-1996-2004-gm-truck-suv-ls-swaps","title":"H104 Indicator Light Adapter Harness | 1996-2004 GM Truck \u0026 SUV \u0026 LS Swaps","description":"\u003cp\u003e\u003cem\u003eStop dealing with the dreaded \"check battery\" light and charging gremlins after your high-output alternator upgrade.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch2\u003eUpgrade Mechman Indicator Light Harness for GM Trucks \u0026amp; SUVs (GMT800\/GMT400)\u003c\/h2\u003e\n\n\u003cp\u003eWhen you bolt a high-output hairpin alternator onto the GMT800 or late GMT400 platform, the factory wiring often falls short. Guys doing LS engine swaps or dropping massive audio systems into their Tahoes and Silverados know the headache: the alternator is physically mounted and spinning, but the gauge cluster looks like a Christmas tree.\u003c\/p\u003e\n\n\u003cp\u003eThe stock GM harness wasn't designed for the excitation demands of aftermarket high-output units. The Mechman H104 adapter harness bridges that gap. It accepts the factory oval GM alternator plugs and connects directly into your new oval-style Mechman alternator, maintaining a clean, secure connection without hacking up your factory loom.\u003c\/p\u003e\n\n\u003cp\u003eMost importantly, it solves the excitation circuit issue. By running the extended blue wire to an ignition-switched 12V+ source, you guarantee the alternator turns on and off with the key. This eliminates the persistent \"check battery\" dash light and prevents parasitic battery drain when parked. It is also the perfect clean-slate solution for standalone engine swaps where the original truck harness is long gone.\u003c\/p\u003e\n\n\u003ch2\u003eWhy You Need This Upgrade\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePlug-and-Play Oval Connectors:\u003c\/strong\u003e Mates seamlessly with oval GM factory plugs and Mechman hairpin alternators, preventing unreliable spliced connections.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eKills the Dash Light:\u003c\/strong\u003e Properly excites the alternator via the ignition switch, keeping your gauge cluster clear of annoying battery warning indicators.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eEngine Swap Ready:\u003c\/strong\u003e Easily hardwired into any standalone 12V+ ignition source, making it essential for custom LS or Vortec transplant builds.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePrevents Parasitic Drain:\u003c\/strong\u003e Ensures the alternator powers down completely when the key is off, protecting your battery bank from dying overnight.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ctable width=\"100%\" style=\"border-collapse: collapse; border: 1px solid #e0e0e0; margin-bottom: 20px;\"\u003e\n  \u003ctr style=\"background-color: #f9f9f9;\"\u003e\n    \u003ctd style=\"padding: 10px; border: 1px solid #e0e0e0; font-weight: bold;\"\u003eFitment\u003c\/td\u003e\n    \u003ctd style=\"padding: 10px; border: 1px solid #e0e0e0;\"\u003e1996-2004 GM Trucks and SUVs\u003c\/td\u003e\n  \u003c\/tr\u003e\n  \u003ctr\u003e\n    \u003ctd style=\"padding: 10px; border: 1px solid #e0e0e0; font-weight: bold;\"\u003eEngine Code\u003c\/td\u003e\n    \u003ctd style=\"padding: 10px; border: 1px solid #e0e0e0;\"\u003eGen III LS \/ Vortec (SBC)\u003c\/td\u003e\n  \u003c\/tr\u003e\n  \u003ctr style=\"background-color: #f9f9f9;\"\u003e\n    \u003ctd style=\"padding: 10px; border: 1px solid #e0e0e0; font-weight: bold;\"\u003eInstallation\u003c\/td\u003e\n    \u003ctd style=\"padding: 10px; border: 1px solid #e0e0e0;\"\u003eBeginner \/ 15-30 Minutes\u003c\/td\u003e\n  \u003c\/tr\u003e\n  \u003ctr\u003e\n    \u003ctd style=\"padding: 10px; border: 1px solid #e0e0e0; font-weight: bold;\"\u003eMaterial\u003c\/td\u003e\n    \u003ctd style=\"padding: 10px; border: 1px solid #e0e0e0;\"\u003eOEM-Grade Wiring \u0026amp; Plastic \/ Oval Style Plugs\u003c\/td\u003e\n  \u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eInstallation Notes\u003c\/h3\u003e\n\u003cp\u003eInstallation is straightforward. The adapter clicks into the factory oval plug. The extended blue wire must be routed to a true ignition-switched 12V+ source. Do not wire this to a constant 12V+ battery source, or you will drain your battery overnight. A multimeter is highly recommended to verify your chosen 12V+ source drops to zero when the ignition is turned off.\u003c\/p\u003e\n\n\u003ch3\u003eReplaces These OEM Applications \u0026amp; Part Numbers\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e1996-2004 GM Trucks\u003c\/li\u003e\n  \u003cli\u003e1996-2004 GM SUVs\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp style=\"font-family: monospace; font-size: 0.9em; color: #666; background-color: #f5f5f5; padding: 10px; border-radius: 4px;\"\u003eH104\u003c\/p\u003e\n\n\u003ch3\u003eCommon Question\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eWill this work if I am swapping a 5.3L into an older chassis?\u003c\/strong\u003e\u003cbr\u003e \nAbsolutely. This harness is designed exactly for those situations. Even if the stock 1996-2004 GM Truck harness is missing or heavily modified, you can hardwire the longer blue wire directly to a switched 12V+ ignition source to get your high-output alternator charging perfectly.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eLock in reliable voltage and keep your dash clean. Grab this harness and finish your charging system upgrade the right way.\u003c\/strong\u003e\u003c\/p\u003e","brand":"VelocityMax","offers":[{"title":"Default Title","offer_id":67700075921656,"sku":null,"price":49.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0800\/1290\/2648\/files\/s-l1600_1_36c4c28c-8ca2-4959-a105-16b654b20d0e.webp?v=1792164672","url":"https:\/\/performancechiptuning.com\/fr\/products\/h104-indicator-light-adapter-harness-1996-2004-gm-truck-suv-ls-swaps","provider":"Performance Chip Tuning","version":"1.0","type":"link"}