I got a lighted Toggle from Radio shack today with the intention Of putting in a Tconverter Lockup, But then I Got to Thinking, Since the Switch Grounds out through the same Lead as the Light, Im going to be sending 12.5v Into the ECU, I want to Make sure thats Not a problem Before I do it...


As I understand it, I connect One of the terminals To the other On the ECU Via a Toggle, thats simple Enough. This Lighted Switch takes 12.5 Tapped off the Light under the Shifter and grounds that out Via the Switchs ground.. **** now im confusing myself.

Anyhow, WIth a 3 terminal LIghted Toggle, One going to One Connecter on the ECU, another Going to the other Connector, and The third a Hot 12.5, Am I going to Damage the computer? Im not going to install it Untill I get an answer

thnx guys, this electrical **** Confuses me sometimes


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60 Ranchero - Project ( Money Hole )
85 Z28 LG4 - Daily Driver
**Mods**
MSD Superconductors
14" Open Element
KYB all around

 

There are three terminals on the switch - they may be labeled as follows:

+Power
Accessory
Ground

The "power" terminal goes to one side of the switch contacts. The "accessory" terminal goes to the other side of the switch contacts, and one side of the light bulb. The "ground" terminal goes to the other side of the light bulb. If the switch terminals are not labeled, use an ohm meter to identify the switch termianls.

In your application, the "power" terminal connects to chassis ground, the "accessory" terminal connects to the TCC wire, at the ECM, and the "ground" wire connects to +12 volt ignition power. In this configuration, turning the switch on will ground the TCC circuit, and one side of the light bulb in the switch (the other side of the light bulb is connected to +12 volts). The ECM TCC output is most likely a transistor open collector, which simply grounds the circuit when it is active, and is high impedance when it is inactive, so the +12 volts connected to one side of the light bulb in the switch will not hurt the ECM, unless the current draw of the light bulb exceeds the curent capacity of the transistor in the ECM, which is not the case with a typical illuminated switch light bulb.

One thing to be aware of is that some switches, while in the "off" position, connect the "ground" and "accessory" terminals together, rather than leaving the "accessory" termianl open. Do not use a switch that functions like this, as the ECM will be damaged due to the switch shorting +12 volt ignition power (on the "ground" terminal") to the TCC circuit (on the "accessory" termianl) when the switch is in the off position.

Tim