GM Electronic Throttle Body Circuit Descriptions and Testing Tips

‘Fly-by-wire’ systems are being used in a lot of cars and pickups on the road today... and one of the most common ‘Fly-by-Wire’ systems in use is the one that graces most of the newer GM pickups: the Electronic Throttle Body.

Everything you read about these systems indicate that they are the best thing to ever happen to automobiles. One of the statements that really makes me laugh is this one: “The ETC delivers outstanding throttle response and greater reliability than a mechanical connection”.

The problems I've had with a throttle cable are so few and so far inbetween that I don't recall when was the last time I replaced one.... When was the last time you replaced a throttle cable?

OK, enough of my ranting... in this article, I'll focus on the circuits of the Electronic Throttle Body and how to perform some basic tests on it. You may also be interested in the following tutorials:

  1. P0120 TP Sensor 1 Circuit Malfunction (with Electronic Throttle Body).
  2. P0220 TP Sensor 2 Circuit Malfunction (with Electronic Throttle Body).

En Español Puedes encontrar este tutorial en Español aquí: Lo Esencial del Cuerpo del Acelerador Electrónico (GM 5.3L, 6.0L) (en: autotecnico-online.com).

Circuit Descriptions Of The GM Electronic Throttle Body

Circuit Descriptions Of The GM Electronic Throttle Body. GM Electronic Throttle Body Circuit Descriptions and Testing Tips

There are three major components of the GM Electronic Throttle Body and they are:

  1. Throttle body.
  2. Throttle Actuator Control (TAC) module.
  3. And Accelerator Pedal Assembly.

In this section, we'll focus on the Electronic Throttle Body. As you have probably already observed, there are 8 wires sticking out of the Electronic Throttle Body.

When looking down at the Electronic Throttle Body's connector, the top row (from left to right) has 4 wires which are labeled from A to D (see photo).

The second row (bottom row) from left to right, the wires are labeled E to H (see photo).

... and here are their specific descriptions:


  1. A: (Yellow wire) TAC Motor Control -1.
  2. B: (Black with White stripe wire) Low Reference... Sensor Ground.
  3. C: (Brown wire) TAC Motor Control -2.
  4. D: (Black) Low Reference... Sensor Ground.
  5. E: (Light Blue with Black wire) 5 Volt Reference.
  6. F: (Purple) TP Sensor 2 Signal.
  7. G: (Dark Green) TP Sensor 1 Signal.
  8. H: (Grey) 5 Volt Reference.

Let's turn the page and find out how the throttle body works in this system...