3500 Throttle Body Pinout

[IsaacHayes]

You can open it up and make it close all the way when powered off BTW.

[Joseph Upson]

Unless there is a circuit board in the TB that I missed or one in the pedal assembly there shouldn't be any regulation at all when you do a direct connect between the two parts. Chances are you may have to ground a few of the outputs together on the TB terminal to the PCM where the final throttle output is determined regardless of pedal position and returned to the TB.

In other words, the PCM is almost certainly a second source of variable resistance that has to be bypassed and more likely than not it is a series circuit, but then you should be able to determine that by the wiring diagram.

[TurboProject]

There must be come circuitry sealed into the plastic housing on the throttle body. There are a lot more brains in there than just wires coming into it...
The TPS is also molded into that housing.

[Joseph Upson]

There must be come circuitry sealed into the plastic housing on the throttle body. There are a lot more brains in there than just wires coming into it...
The TPS is also molded into that housing.

I opened the TPS molding and there is nothing in there except a dual contact slide over a variable resistance patch. It's been a while since I looked at it so who knows. I didn't see anything else suggesting more circuitry. I figure 4 wires for the slide and two wires for the motor, double that add pairs and that should account for about ten terminals.

[TurboProject]

Did you break into the part where the connector comes in? I'm just thinking there's got to me more if 13 wires come in and there are only 2 going to the motor and there is just that TPS sensor in there. There has to be something to communicate with those serial lines coming from the computer.

[Joseph Upson]

Did you break into the part where the connector comes in? I'm just thinking there's got to me more if 13 wires come in and there are only 2 going to the motor and there is just that TPS sensor in there. There has to be something to communicate with those serial lines coming from the computer.

No, looks like your power input is at the ignition and the stop light terminal, which appears to function like the torque converter or cruise shut off when brakes are applied. The motor does not appear to be fed directly by any of the external terminals unlsess you probe both of its cover terminals against the outside terminals and get a closed circuit reading.

The 3 serial associated wires are all that's left and at least one of them has to vary the the throttle voltage. It makes sense to have the speedometer signal involved more so for cruise control when it's activated since just as in the mechanical throttle body you have separate accelerator and cruise cables. That way you have an input for cruise speed maintenance, and another input for when you apply more power above the set cruise speed which will hold its position when you remove your foot from the pedal.

I have no documentation to prove any of that, I'm just reasoning.