The GM-46091 Charge Air Cooler Tester has been used to leak-check induction systems on vehicles equipped with a 6.6L Duramax diesel engine since 2001. Various adapters for this base tool have been developed as vehicle and powertrain changes have occurred. The XLDE 2.8L Colorado/Canyon diagnostics require the use of previously essential tools, specifically GM-46091 and GM-47656-NA Pressure Test Adapter Plug, to plug, seal, and pressurize the induction system with air for leak testing.

GM-47656-75 is an NPT fitting and quick-connect adapter installed by the dealer in the GM-47656-NA to modify the Adapter Plug, allowing for the relocation of the plug in the induction system for improved access during diagnostic procedures using GM-46091. The dealer removes the tire valve stem in the plug and uses a standard ¼”-18 NPT tap to thread the hole for the fittings. Modification instructions are

included in the kit.