How to Make Smoke Switches on LB7s

by Jeremiah Blanchard

The Duramax LB7 is a diesel engine that was manufactured from 2001 to 2004. This engine was commonly installed in large trucks such as the Chevy Silverado HD and GMC Sierra HD and is still in circulation as of 2011. A smoke switch is used for tricking the engine sensors into expending more fuel, resulting in a large cloud of smoke being forced out of the exhaust. A smoke switch can be made for LB7 engines with little difficulty.

Step 1

Choose a location in the vehicle to install the switch. This is generally up to personal preference, but, typically, below the steering wheel on the dashboard or any accessible area with mounting space is ideal.

Step 2

Strip 1 inch of insulation off the toggle switch wire's conductors using wire strippers. Insert a flat component connector onto the end of each wire and compress them with pliers.

Step 3

Drill a hole in the dashboard for the toggle switch. Run the toggle switch wires though the hole. Tape the switch in place temporarily.

Step 4

Locate the round grommet under the dashboard in the right corner. This grommet leads into the engine. Drill a small hole at the center of the grommet. Run the toggle switch wires through the hole and into the engine compartment. Open the hood. Disconnect the truck battery connections.

Step 5

Locate the engine map sensor using the truck's manual. As LB7 engines were installed on several truck models, this step will vary. Use the manual's circuit diagram to tell which wire runs the map signal.

Step 6

Disconnect the map sensor wire. Strip 1 inch of insulation off of the map sensor wire. Run the wire from the toggle switch to the map sensor wire. Connect the other wire from the toggle switch to either of the remaining wires on the map sensor.

Step 7

Secure all of the stripped wire connections with electrical tape. Reconnect the battery. Start the vehicle. Rev up the engine and flip the toggle switch to test. Black smoke will force out of the exhaust when the switch is flipped. Remove the tape from the toggle switch. Apply fast setting adhesive around the drilled hole. Hold the toggle switch on the adhesive until it sets.

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