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M.L. Toys
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Need new batteries? Going from 12V to 18V or 6V to 12V? Wiring Questions?

I had a Kid Trax 6v SRT Viper given to my son when he was 6 months. He's now 13 months and able to reach the pedal and drive it around. Although still a bit young to not crash into things. I am a programmer by trade and love to tinker but just getting into electronics. My first mod is a parental kill switch powered by an Arduino onboard the car and either a small standalone remote or bluetooth on my phone.

Yesterday I took apart the car to try and understand the wiring. I bit more complex than I originally anticipated but through some research I did learn about feedback breaking, why there is a cap across the motor feeds, the direction switch, etc. I believe I have everything I need to integrate my arduino, but there is one wire I don't understand. Not crucial to my mod but I can't let it go.


6 Grid Connector
[ pos ] [ to motor] [ neg ]
[ neg ] [ to motor] [ pos ]

To Battery / Motor
Black/Red to grid connector goes to motor
Black (to pedal) is negative from battery
White/gray (to power switch) is positive from battery

To Power Switch
White/gray is positive from battery
Red is from other side of simple switch

To Pedal
Black is from battery negative
Blue (I'm guessing) is when pedal is depressed, connects negative to grid connector
White/gray - I'm not sure what this is (brake maybe)?

My confusion is the white/gray from pedal to positive side of grid connector. If this is the connection made when the pedal is not pressed, wouldn't it short the battery and not the motor (brake)? I haven't tried to remove the pedal yet, but the tubing over the wires sure don't make it easy to trace things down.

Actually, I think I will need to fully understand this otherwise I may lose the break feature when the remote kill is enabled.

My plan was to run a positive wire of the upper left (where the positive headlight wire connects) to power the arduino. That way its only powered when the vehicle is powered on. The relay I was going to put on one of the terminals of the motor. But if I do that, when the relay is open (remote kill triggered) there will be no brake.

The other question I have to look into is the charging. There are three wires coming off the charging port and somehow everything is disabled when the charger is plugged in.
Hi Sam. You're correct that if you wire a single relay to the battery lines, the brake will not be forced to engage. In order to have your relay cut power and engage the brake, you will need an understanding of the terminals on your gas pedal. I don't have a reference guide that will tell you what pin does what, but it's fairly simple to figure out if you have an ohm meter.

You can use the ohm meter to figure out which pins are open in which pedal state (pressed / released). Once you know that, you can use a couple SPDT relays to replicate the actions at the prompting of the remote kill "box".

That being said, most of these vehicles will slow dramatically just by cutting power, even without the motor feedback. Unless you're on a hill, it'll stop pretty fast.

Let me know if you're still interested and I'll take a shot at a schematic.

Also, that's your shifter in the image right?
Last edited by SoonerWilliams on Wed Oct 22, 2014 8:26 am, edited 1 time in total.
Yes, this is the plug that connects into the shifter (direction switch). It doesn't have high/low.

The diagram in the FAQ makes sense - 2nd picture right side in my case. However, on my car, the lines to the motor seem to be connected to the middle pins rather than the end. In the FAQ diagram, the battery is connected to the middle pins.
Alright, I'll take a shot at where I would start if I were you :)

First, you really care about the three lines associated with the brake line rather than the shifter - The black, white, and blue in the bottom right of your image

The three wires at the pedal ultimately break down to a battery +, motor -, and motor + even though they may go through the shifter in the process.

All you need to do is take your pedal out, ohm it out and figure out which connections are shorted (near 0 ohm resistance) in each state. That will tell you how you need to wire your relay.

My guess is that the black to pedal is your motor -, the white to pedal is battery + and the blue to pedal is motor +. But a voltmeter will answer that question for you very quickly.

you can power your remote kill receiver by tapping into the headlight lines as you previously thought.

I'll put together a little diagram.
Last edited by SoonerWilliams on Wed Oct 22, 2014 11:07 am, edited 2 times in total.
The car is back together currently so its drive-able. Will pull it back apart again and test again. What you are saying makes sense, but I don't think that's how its wired. The wires are in tubes all over, so I can't see any connections within the tubes.

I think the center wires in the 6 grid connector are to the motor. I have continuity between the motor and these two wires. Also, if I try to take a voltage putting negative on the upper center pin in the grid connector (black wire) and positive on the battery, I get nothing. I think the black wire going into the "to pedal" is directly from battery negative which is why I was confused the other two would be going to both positive and negative in the grid connector.

Also, I can measure the battery voltage using the white wire going into the "to power switch" tube as positive and battery as negative even when the switch is off. Also confusing because coming out of the tube in the back going to the battery is only red and black so it must change colors somewhere in the tube. Maybe to do with the charging port.
Thanks. I wouldn't spend too much time updating until I can confirm things. I may just cut the tubing so I can really see what is going on.

On another question... Any diagrams on how the charging circuit work? When it's plugged in power is disabled and it doesn't drive. Standard barrel connector but has 3 wires coming off the back.
And now your schematic with the remote kill (including brake feedback) in place. The only omission is that you'll have the remote kill receiver output it's signal to the Kill Relay coils. When the kill is engaged, the coils will receive voltage which will disconnect the negative line and join the motor terminals.

Whew! Please let me know if this works!
RKSchem.png (42.02 KiB) Viewed 4993 times

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