Throttle Position Switch Installation Instructions:
(Please read this entire instruction set before you begin)
Congratulations on your purchase of a Throttle Position Switch! This device is intended to switch a 12v device, on or off, depending upon throttle position. It is intended for use with our Multi-Stage Boost Control (MSBC), to limit part-throttle boost, but may be used to switch other devices. Note that the switching capacity of the internal circuitry is 2A at 12V. To switch a larger current (such as a nitrous solenoid) a 12v relay must be added to your circuit. Radio Shack part number 275-226 may be used for this purpose. Please note that the Throttle Position Switch case is NOT weather-tight and is intended to be mounted inside the passenger compartment (under the dash is a good location).
For the device to function properly, the signal from the throttle position sensor must vary between 0v and 5v when the throttle is moved. It does not matter if the signal voltage increases or decreases with throttle position, as the device is switchable for the two conditions. Before starting, ensure that you have properly identified the signal wire on your vehicle’s throttle position sensor and that it gives a reading that rises toward the 5v level (or falls from 5v toward 0v) when the key is on and the throttle pedal is depressed. It is usually not necessary for the vehicle to be running, only that the key be in the "on" position. Although a voltmeter is NOT required for the adjustment of our device, one may be useful if you do not know which wire provides the signal voltage from the throttle position sensor.
The Throttle Position Switch has four connection wires, which are color coded as follows:
Red: Switched12v (connect to a 5A inline fused, or fuse block location that turns off when the key is turned off)
Black: Chassis Ground
White: Signal output from throttle position sensor
Green: 12V output to Multi-Stage Boost Control, or other device. This wire will supply 12v when the tuning LED is on.
Before we begin the installation, remove the small phillips screw in the case and put it in a safe place. Remove the cover from the Throttle Position Switch, so that the internal components can be viewed.
Note that there is a clear LED (light) at one end of the case, which we will refer to as the tuning LED. When this light is illuminated, the green wire will have 12v supplied to it. You may hear a small clicking noise as this light turns on and off.
You will also notice a black switch, which controls whether the Throttle Position Switch will be used for a rising or falling throttle position sensor signal.
Last, is a blue potentiometer (dial) that is used to adjust the throttle position that will activate the switch. This will be adjusted with a small screwdriver. Be careful to rotate this dial slowly and note that it has slightly less than one turn (about 340 degrees) of travel. Take care not to rotate the dial beyond it’s intended travel.
OK, let’s get started with the installation. First, wrap a piece of electrical tape or other suitable insulation around the end of the green wire. This will ensure that it does not accidentally short circuit during the installation.
Connect the black wire to chassis ground. This can be any bare metal contact under the dash, which connects with the vehicle chassis. If you are not sure whether the metal is grounded, connect one wire from a voltmeter to the surface and the other to the battery 12v terminal. If you read battery voltage, you have found a suitable grounding location.
Now connect the red wire to 12v. This input should be from a switched circuit that turns off with the vehicle. It should also be fused at no more than 5A. If needed, an inline fuse may be added to the red wire, for this purpose. Radio Shack part number 270-1238 is a suitable part for this function.
Connect the white wire on the Throttle Position Switch to the wire which you have identified as the signal from the throttle position sensor. Note that you will "tee" into the throttle position sensor signal wire (parallel connection). This can be done at the sensor, or at the ECU. The white wire may need to be extended if it needs to be run into the engine compartment. In either case, take care that the wire is not near any source of abrasion or extremely hot parts, such as the exhaust manifold.
You are now ready to tune the device.
With the key in the "on" position, hold the throttle at the approximate position where you want the switch to activate. In the case of the Multi-Stage Boost Controller, this will be about 75% of full throttle. Gently turn the potentiometer dial to the point where the red light comes on (don’t worry if the light is already on—just turn to where it goes off and then turn it until it comes on). Now release the throttle and the light should go out. If it does not, then flip the black slide switch to the opposite position. Now press the throttle down and the light should come on when you reach the position that you tuned to (75% of throttle). If not, adjust the potentiometer until you find the position that is right for you. So, if you did everything correctly, the light should go out when you let the pedal up and turn on when you press the pedal down. If this does not happen, check to see that the signal from the throttle position sensor changes between 0v and 5v (or 5v and 0v) when the pedal is pushed.
(If you would prefer to switch OFF a device, which is ordinarily on, just flip the slide switch to the other setting. The green wire will output 12v until the throttle position is reached, however, the first configuration is generally used---Remember, when the light is on, there is 12v at the green wire)
Now, turn the ignition to the off position and connect the green wire to the 12v input of the device to be switched. Consult the schematic below for connection to our Multi-Stage Boost Control. Make any other connections to the switched device as described in its instruction set. Turn the ignition back on and test the operation of the device to ensure that it functions at the appropriate throttle position. Note that a clicking noise will be heard from the MSBC when it activates. Replace the cover on the Throttle Position Switch.
The following schematic shows how to connect the TPS to control our Multi-Stage Boost Control to activate when throttle position exceeds the set point. Other devices can be activated by connecting the green wire to their 12v input.
