Interfacing to the Intake Air Temperature Sensor

One wire: white

This is an optional sensor. If this sensor is not connected, the TDS-1 will skip over the IAT mode.

The Intake Air Temperature (IAT) sensor allows the ECU to monitor the charge air temperature, and adjust engine parameters to prevent detonation when the IAT gets excessively hot. This information is useful for the driver as well, in order to monitor their intercooler and turbocharger efficiency. For details on how this sensor works, click here.

The IAT sensor harness has two positions. One of them connects to ground inside the harness. The other connects to the ECU on ECU connector position 44. This connection is made directly via a brown with blue stripe wire. Unfortunately there is no intermediate harness connector. This brown/blue wire must be connected to the TDS-1 for the IAT function to work. The connection can be made in the engine compartment, or in the wire bundle leading to the ECU.

The easist place to make the connection is in the ECU harness. You are looking for the brown with blue stripe wire. You can see the other end of this wire on the IAT connector near the throttle body.

Te best way to make this connection is by making a splice and heat shrinking it:

To make the splice without shortening the brown/blue wire relative to the other wires in the harness, a piece of wire about 1.5 inches long should be used, in such a way that there are two separate splices. The first is the brown/blue wire from the ECU to the 1.5 inch wire, the second is between the 1.5 inch wire, the white wire to the TDS-1, and the brown/blue wire to the sensor in the engine bay. A single piece of heat shrink can cover both splices, as in the above picture.

An easier method is to use a "vampire tap", which are available from electronics and auto parts stores. These are not watertight, and would appear to be less reliable than the heat shrink method.