5.3l throttle by wire not functioning

[Jfarns03]

I have everything in my 68' C10 wired and ready to go. Fuel pump turns on and I get plenty of pressure but my motor won't start. It came down to the throttle body is not working. It doesn't open when I press the gas pedal. So what I think the problem is, is that it won't start because no gas is getting to the motor because the throttle body isn't working. Here's where it gets tricky though. Not long ago I personally seen it open and close so I know it has to be a wire problem. What do you guys think?

[kalbert]

If it was only the blade not opening I'd expect it to start and idle but not come off idle. Sounds like there is more missing that just that. Is it just the throttle blade that is inoperable or is there more that is not working? Have you been able to communicate with the ecm to determine that it is powered and reporting status correctly?

[Jfarns03]

I do not have communication with the ECM. The blade on the TB does not open/function so I think in essence it is not opening the fuel injection to feed the engine with fuel

[Goats86]

check your ground wires. i left one off when i did mine

[Jfarns03]

Ground wires? I don't know what your talking about. It's all plugs?

[Goats86]

factory harness has 3 ground points. usually 1 behind the power steering pump and 2 near the back of the heads if i remember correctly

[Jfarns03]

Oh okay I understand. I thought you meant the gas pedal harness itself. I will check it out !

[88Ironduke]

Just finished a 5.3 install into an 81' Firebird so I feel your pain when it won't fire off. The throttle plate won't budge when not running. First question I have is do you have spark?
Your spark control is derived from the crank position sensor (behind starter), secondly injector control derives from the cam sensor on the back of then engine where an old school distributor would. The connectors are interchangeable so ensure the pin outs are correct.

If you crank and have no spark the ECM is not seeing rotation and therefore will not fire the injectors accordingly. The throttle pedal assembly electronics are delicate and do not like welders operating nearby, I bought a new pedal assembly......

Most importantly is getting a code scanner and plugging into the ODB port and see what the computer is reporting. Work the fault codes and get it running! Good luck.

88Ironduke

[Jfarns03]

Thanks guy! There's a performance shop right up the street from me who has a code scanner and I'm goin to have them handle it all for me. I'm over dealing with electronics but im going to show them what you had to say Ironduke just to make it easier for them