I have a 2002 corvette with a swapped LS3 and a LS2 throttle body, drive by wire, that goes into limp mode after about 5 hard laps, its a dedicated track car.

I was getting codes: P1220, P1221, P1515. Car ran great up to it getting hot. Oil temps 250 and water temps 201.

But I want to run a TB test procedure on it, namely the TPS limits etc.

Does anyone have the procedure, what wires get tested etc, using a multimeter with Ohms and volts parameters? THX!

 

When a P1221 is set with a P1515, the test procedure calls for a scanner to compare the TP angle. You will need a meter and a scanner.

 

I made a bench tester for them but it’s not helpful for heat-related issues, which tends to be the most common failure mode. If it is a GM unit, I would recommend opening it up and cleaning the brush. If errors continue, replace it.

 

We see issues with these swapped TB's...the OE TB are basically 2 potentiometers that work with voltages that work in opposite directions from idle to WOT...TPS1 goes from low to high voltage and TPS2 goes from high to low...your P1220 is a TPS2 issue...to check you can use either a scan tool or with a DVOM...if no scan tool backprobe the PINK TPS2 sensor wire with key ON....in the picture I am using a T pin instead of a back probe...at idle as shown on my 2001 you should see around 3.8 volts and then push the gas pedal to the floor...you should see less than 1 volt...in the picture below I was reading a little high at 3.94 volts but I had no issues...with TPS1 you should see less than 1 volt to above 3.5 volts at WOT...now on my 2008 LS3 my TPS sensor works the OPPOSITE way...TPS1 is "pulled down" from a high to low voltage and TPS2 is "pulled up" from a low voltage to a high voltage...if you see voltages like my LS3 on your LS1 engine it ain't gonna work !!...the engine computer isn't seeing what it should be seeing...I don't know if they make an adapter harness for this...even if the voltages are correct but out of the range you will have issues too. ...my LS3 TPS2 scan data shows 1.275 volts at idle and 4.392 at WOT.






TPS2 idle

TPS2 WOT

LS3 TPS2 WOT

LS3 TPS2 IDLE

 

Excellent! Thanks I will try this tomorrow. It is a Gen3 car with Gen4 TB and MAP sensors. Im gonna try and clean TB and run this test. THX!

 

Oh and I do have HP tuners and was watching the Throttle Position vs Throttle desired position and seemed pretty close. Oh and it is a silver TB blade. Early version.

oh and it does have a Racetronix TB wiring harness adapter.....

 

Even if desired and actual are close it does tell you whether it’s a pull up or pull down circuit going from idle to WOT…that’s what is important and the voltage value !!