Are the LS2 truck throttle bodies interchangeable with the LS2 car throttle bodies if physical dimensions were not an issue? I have an 08 TBSS that I am installing a T-56 into and I am running two ECMs. The motor is being run off an 07 CTS-V ecm and the TBSS ecm is running the guages and everything else. The motor starts and runs just fine, all guages work, but I dont have throttle. I am using a brand new 07 cts-v accelerator pedal. I have verified all wiring at the pedal and ecm to be correct. The pinout for the TBSS TB and the CTS-V TB are identical. Thanks!

 

Trucks usually have TP Sensor 1 and TP Sensor 2 opposite of cars. i.e.
Car TP Sensor 1 = Truck TP Sensor 2
Car TP Sensor 2 = Truck TP Sensor 1

Did you check the wiring schematic for the CTS-V to confirm throttle position sensor configuration? The throttle body pin outs may be the same, but the PCM wiring may be opposite.

 

According to the pinouts and schematics, everything is the same between the two vehicles.

 

If you have the service manual for both vehicles, look in the engine controls section for the description of throttle position operation.

Here are excerpts from service manuals of what I'm talking about:

Truck:
"The TP sensor is actually 2 individual TP sensors within one housing. Separate signal, low reference, and 5-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 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 throttle to below 1.0 volt at 100 percent throttle."

LS2:
"There are 2 individual TP sensors within the throttle body assembly. The TP sensors are used to determine the throttle plate angle. The TP sensors provide the ECM with a signal voltage proportional to throttle plate movement. The TP sensor 1 signal voltage at closed throttle is above 4 volts and decreases as the throttle plate is opened. The TP sensor 2 signal voltage at closed throttle is below 1 volt and increases as the throttle plate is opened."


Are you getting any codes?

 

[ECM] P0315 - Crankshaft Position System Variation Not Learned (SES) (Pending) (Old) (History) (Current) (Immature)
[ECM] P060D - Internal Control Module Accelerator Pedal Position Performance (SES) (Pending) (History) (Current) (Immature)
[ECM] P2119 - Throttle Actuator Control Throttle Body Range/Performance (Pending) (Old) (History) (Current) (Immature)
[ECM] P2138 - Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation (SES) (Pending) (History) (Current) (Immature)
[ECM] P0315 - Crankshaft Position System Variation Not Learned
[ECM] P060D - Internal Control Module Accelerator Pedal Position Performance
[ECM] P2138 - Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation

I have verified that the ecm is getting the correct signals from the APP so I know that the problem not with the pedal or pedal wiring to the ecm.

 

You should try reversing the TP1 and TP2 sensor wires at the throttle body.

 

Just tried it and it didnt work. It would even let the motor turn over when I tried to start it. It probably thought the throttle blade was wide open.

 

Shoot [kicks the ground]! Did you look in the manual for the troubleshooting steps for DTC P2138?

 

Did you solve the problem?

I'm having the same (no throttle problem) but I'm not using as new of stuff as you are. Perhaps the same problem though.

 

I am using a E40 LS2 computer to control a 78mm LS1 truck style throttle body.
here is how I wired it;
6 pin 8 PIN
A 582 C 582
B 581 A 581
C 1704 B&H 1704 & 416
D 485 G 485
E 1688 D&E 452 & 1688
F 486 F 486

-wiht the key on multi meter black probe on 6 pin C 1704 low refernce and the red probe on d 485 tps1. I get 3 volts closed and 0 volts WOT

-wiht the key on multi meter black probe on 6 pin C 1704 low refernce and the red probe on F 486 tps2. I get o volts closed and 3 volts WOT

So I am getting them to move in the oposite directions like the E40 PCM wants how ever the PCM never moves the throttle blade at all so it is at rest in the slightly open postion, also my multimeter round voltages up or down, to the nearest volt, so I might be getting 3.4999 volts and .499 volts instead of 3 volts and zero volts.

I am getting codes;
[ECM] P0315 - Crankshaft Position System Variation Not Learned (SES) (Pending) (Old) (History) (Current) (Immature)
[ECM] P0449 - Evaporative Emission (EVAP) Vent Solenoid Control Circuit (SES) (Pending) (Old) (History) (Current) (Immature)
[ECM] P0463 - Fuel Level Sensor Circuit High Voltage (Pending) (Old) (Current) (Immature)
[ECM] P0532 - Air Conditioning (A/C) Refrigerant Pressure Sensor Circuit Low Voltage (Pending) (Old) (History) (Current) (Immature)
[ECM] P0689 - ECM/PCM Power Relay Sense Circuit Low (Pending) (Old) (Current) (Immature)
[ECM] P1682 - Driver 5 Line 2 (Pending) (Current) (Immature)
[ECM] P2119 - Throttle Actuator Control Throttle Body Range/Performance (Pending) (History) (Current) (Immature)
[ECM] P2138 - Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation (SES) (Pending) (History) (Current) (Immature)
[ECM] P0315 - Crankshaft Position System Variation Not Learned
[ECM] P0449 - Evaporative Emission (EVAP) Vent Solenoid Control Circuit
[ECM] P2138 - Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation

the engine will start but only in REP mode.

My question is do yo know what the resister or diode is between the 5 volt refernce line? I may need to replicate that. Also are there anything seporating the low refernce lines resistor or diode? THanks Jamie

If I put a resister inline on the low reference circuit would it allow the 5 volt refernce line to creep up to above 4 volts instead of 3.5 volts? Ifso what size a resistor, and how would this effect the low ref voltage?

does P2138 have to do wiht the pedal itself how can I use Hp tunners to check that the PCm is seeing the proper numbers form the pedal?

 

I hooked up circuit 839 to the igniotn switch and tied two bat 440 circuits togther I only had one wired to the pcm, after this the throttle plate cliced and moved closed when I turn the key on, I still got code P2138 so I swiched the high and low ref wires around on one of the pedal senors and now it runs and accelorates, but wiht these codes;

[ECM] P0315 - Crankshaft Position System Variation Not Learned (SES) (Pending) (Old) (History) (Current) (Immature)
[ECM] P0449 - Evaporative Emission (EVAP) Vent Solenoid Control Circuit (Pending) (Old) (History) (Current) (Immature)
[ECM] P0480 - Cooling Fan Relay 1 Control Circuit (Pending) (Old) (Current) (Immature)
[ECM] P0481 - Cooling Fan Relay 2 Control Circuit (Pending) (Old) (Current) (Immature)
[ECM] P0532 - Air Conditioning (A/C) Refrigerant Pressure Sensor Circuit Low Voltage (Pending) (Old) (History) (Current) (Immature)
[ECM] P0654 - Engine RPM Output Circuit Malfunction (Pending) (Old) (History) (Current) (Immature)
[ECM] P2119 - Throttle Actuator Control Throttle Body Range/Performance (Pending) (Old) (History) (Current) (Immature)
[ECM] P0315 - Crankshaft Position System Variation Not Learned
[ECM] P0449 - Evaporative Emission (EVAP) Vent Solenoid Control Circuit