2003+ electric TB technical info
Jan 26, 2006 | 08:48 PM
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2003+ electric TB technical info
With all the 90mm electric TB threads going on right now, I thought it might be good to share this info with the group:
The 03+ trucks and SUVs use a throttle body with two throttle position sensors. Each sensor is fed a +5v and ground reference signal. Depending on the throttle blade angle, the output voltage is read from near 0 in the closed position and near 5v at WOT. The pedal assembly has a similar design with two sensors working on the same 0 to +5v scale. There is a control module that watches the TB and pedal and reports to the PCM the throttle position. Sensor 1 on the pedal setup is compared to sensor 1 on the TB, and they should have close values at all throttle positions. The same thing for sensor 2 on the pedal and throttle body. I think the two sensors are very slightly different, so the PCM will see two values that closely match. There is some internal processing that watches the position the pedal compared to the blade angle. If it detects values in either the pedal or TB systems that don't meet its thresholds, then it sets an engine code. It usually goes into reduced power mode, because if you have a TB failure, you don't want it to be WOT on you.
Now the C5 Vette and LS2 systems are similar in their sensors, with the C5 having a throttle control module like the trucks. The LS2 has a more powerful PCM and all its throttle control stuff is internal. The TB and the pedal both have two positions sensors like the trucks, but there is a big difference in their design. Instead of two seperate +5v and ground inputs, they only supply one 5v and ground. Thats not a big issue, but the sensors work differently. One sensor records 0 to 5v but the other is reversed and reads 5v to 0. In their processing, the values from each sensor are added together for error checking purposes and the total equals roughly 5v. So at low throttle, one sensor reads 1V and the other reads 4v for a total of 5v.
The speartech solution would replace the throttle control components from the truck system with ones that were designed to work with the reversed sensors of the LS2 throttle body.
To assist the do-it-youselfers on this site:
The 03+ trucks and SUVs use a throttle body with two throttle position sensors. Each sensor is fed a +5v and ground reference signal. Depending on the throttle blade angle, the output voltage is read from near 0 in the closed position and near 5v at WOT. The pedal assembly has a similar design with two sensors working on the same 0 to +5v scale. There is a control module that watches the TB and pedal and reports to the PCM the throttle position. Sensor 1 on the pedal setup is compared to sensor 1 on the TB, and they should have close values at all throttle positions. The same thing for sensor 2 on the pedal and throttle body. I think the two sensors are very slightly different, so the PCM will see two values that closely match. There is some internal processing that watches the position the pedal compared to the blade angle. If it detects values in either the pedal or TB systems that don't meet its thresholds, then it sets an engine code. It usually goes into reduced power mode, because if you have a TB failure, you don't want it to be WOT on you.
Now the C5 Vette and LS2 systems are similar in their sensors, with the C5 having a throttle control module like the trucks. The LS2 has a more powerful PCM and all its throttle control stuff is internal. The TB and the pedal both have two positions sensors like the trucks, but there is a big difference in their design. Instead of two seperate +5v and ground inputs, they only supply one 5v and ground. Thats not a big issue, but the sensors work differently. One sensor records 0 to 5v but the other is reversed and reads 5v to 0. In their processing, the values from each sensor are added together for error checking purposes and the total equals roughly 5v. So at low throttle, one sensor reads 1V and the other reads 4v for a total of 5v.
The speartech solution would replace the throttle control components from the truck system with ones that were designed to work with the reversed sensors of the LS2 throttle body.
To assist the do-it-youselfers on this site:
I am glad you posted this, I was not looking forward to this write up. Great work 
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