How would I know what is in his mind? Without the pictures we have requested (haven't we? Can't imagine why not!), we don't quite know
The two leads that say "To Arduino" originally went into the integrated circuit,
It's an RC car. The chip is the radio receiver TAIYA 3-R. Since the receiver is being bypassed for the project it is unnecessary and can be removed. The H-bridge (the heatsinked power transistors) are normally driven by the Receiver chip via resistors. At this point , we have no further information until the OP traces the pins from the chip to the base resistors and then to the power transistor base pins. This can be done more easily by looking at the number on the power transistor, finding the datasheet and finding out which pin is the base pin and then tracing it backwards from there back to the chip which will tell you which pins on the chip are outputs. If it is indeed a receiver chip, there are no "input" pins per se because the input is the radio signal coming in on the antenna, which is decoded by the chip to FORWARD, LEFT,RIGHT and REVERSE. The steering would be independent of the forward and reverse, unless it uses differential drive. We don't know what the car frame looks like so that's an unknown. We need a picture of the bottom of the car.
@raschemmel"one side motors working" does not a working RC car make.Sir, Both sides of the car / both motors are working . They are controlled by 4 lines.
@raschemmelI do not know what signals are there from those control points. I just measured voltage between the point and the ground. Also measured the current when directly sinking to the ground. (When directly sinking one point to the ground I got one side motors working.) I do not have a scope to check the signals.By "academic" , I do not have a real project in hand ? No.. I have some thing solid before me.Or did you mean .. that discussion is going too theoretical ? .. sorry I cant help ;-) asking questions.
Of interest is how much current was involved with shorting places in the circuitto ground?Dwight
....both sides are working but we still don't have a TRUTH TABLE. You have a meter. Why don't you look at the numbers on the heat sinked devices and post those and look for the datasheets. Tell what all the functions are and how they operate.(exactly), not in general (ie:" grounding some points makes the motors work ...." is no help at all)Be specific.What do you propose to do with a receiver chip if you are not going to use it ? Are you planning to leave it in the board ?
You did all this JUST to control it from your phone?