I looked at my 03 manual and the wiring shows that the tps has what looks like 2 sensors?

The diagram refers to them as sensor 1 and sensor 2 and they each have 3 wires...5v reference,low ref and signal.

Anyone know how this works?

Are they just redundant, or do they work in opposite directions, perhaps so that the pcm reads both to compensate for backlash when the throttle plate reverses directions or something?

Any info is appreciated

Thanks

 

ttt

Anyone?

 

Here is a composite of what they do:

Throttle Actuator Control (TAC) System Description

The throttle actuator control (TAC) system uses vehicle electronics and components to calculate and control the position of the throttle blade. This eliminates the need for a mechanical cable attachment from the accelerator pedal to the throttle body. This system also performs the cruise control functions as well.
The TAC system components include but is not limited to the following:
• The Accelerator Pedal Position (APP) sensor
• The Throttle Body
• The Throttle Actuator Control (TAC) module
• The Powertrain Control Module (PCM)
Each of these components interface together to ensure accurate calculations and control of the throttle position.

Accelerator Pedal Position (APP) Sensor

The accelerator pedal position (APP) sensor is mounted on the accelerator pedal assembly. The APP is actually 3 individual accelerator pedal position sensors within 1 housing. Three separate signal, ground and 5.0 volt reference circuits are used to connect the APP and the TAC module. The APP sensor 1 voltage should increase as the accelerator pedal is depressed, from below 1.0 volt at 0 percent pedal travel to above 2.0 volts at 100 percent pedal travel. APP sensor 2 voltage should decrease from above 4.0 volts at 0 percent pedal travel to below 2.9 volts at 100 percent pedal travel. APP sensor 3 voltage should decrease from above 3.8 volts at 0 percent pedal travel to below 3.1 volts at 100 percent pedal travel.

Throttle Body Assembly

The throttle body for the TAC system is similar to a conventional throttle body with a couple of exceptions. One exception being the use of a motor to control the throttle position (TP) instead of a mechanical cable. The other exception is the new design TP sensor. The TP sensor mounts on the side of the throttle body opposite the throttle actuator motor. The TP sensor is actually two individual TP sensors within one housing. Separate signal, ground and 5.0 volt reference circuits are used to connect the TP sensors and the TAC module. The TP sensor 1 signal voltage increases as the throttle opens, from around 1.0 volt at 0 percent throttle to above 3.5 volts at 100 percent throttle. TP sensor 2 signal voltage decreases as the throttle is opened, from around 3.8 volts at 0 percent throttle to below 1.0 volt at 100 percent throttle.

Throttle Actuator Control (TAC) Module

The TAC module is the Control Center for the electronic throttle system. The TAC module and the PCM communicate via a dedicated redundant serial data circuit. The TAC module and the PCM monitor the commanded throttle position and compare it to the actual throttle position. This is accomplished by monitoring the APP and the TP sensor. These two values must be within a calibrated value of each other. The TAC module also monitors each individual circuit of the TP sensor and the APP to verify proper operation.
The throttle position (TP) sensor is mounted on the throttle body assembly. The sensor is actually 2 individual TP sensors within one housing. Two separate signal, ground and 5 volt reference circuits are used in order to connect the TP sensor assembly and the throttle actuator control (TAC) module. The 2 sensors have opposite functionality. The TP sensor 1 signal voltage increases as the throttle opens, from below 1.0 volt at 0 percent throttle to above 3.5 volts at 100 percent throttle. The TP sensor 2 signal voltage decreases from around 3.8 volts at 0 percent throttle to below 1.0 volt at 100 percent throttle. Also observe that the signal circuit for TP Sensor 1 is pulled up to 5 volts and that the signal circuit for TP Sensor 2 is referenced to ground within the TAC module.
A P1221 DTC is set if TP sensor 2 disagrees with TP sensor 1 by more than 7.5 percent. This results in reduced power mode.

You aren't in Kansas anymore.

Bill

 

And I bet that I could have found all that in my oem manual, Yes?

If so, then...

and I must be getting too old for this stuff...

At least I figured out that the sensors work in opposite directions (without a meter)

Thanks a million

I'm up to no good, but in a good way...

 

They are there for redundancy. The gas pedal has three sensors. In a drive by wire system you want to make sure your inputs are real. In the C5 most sensors have an up and a down. Meaning the voltage swings backwards for each sensor, that way the PCM can tell more about a faulty signal.

If you want the technical answer, you are looking at half of a Wheatstone bridge, the other half is in the gas pedal sensor. The throttle controllers job is to keep the each half of the bridge balanced. As you move the pedal you throw the bridge out of balance. The throttle control module moves the throttle blade until the bridge is balanced again.

 

Thanks for the info..

 

Can someone with a service manual post the wire colors for each sensor on the APP?

 

This is from a 2001 Manual

APP1

Low Reference - BROWN
Signal - DK BLUE
5 Volt - LT BLUE

APP2

Low Reference - PURPLE
Signal - LT BLUE
5 Volt - TAN

APP3

Low Reference - GREY
Signal - DK GREEN
5 Volt - YELLOW/BLACK

These are all wired to the TAC Module

 

Thanks for the help.

Interesting note...the C6 has only 2 APP sensors.

 

AKA: Safety