RC Car Toy Modification Help !!!

Hello everyone !!!
i have this 2 RC car toys in the junk ... so i have the idea to modify them into one car that has much power and speed .... So i reassemble them into one frame and i got this one :
*******************


-------------------------


*******************
This new Toy contain 2 DC motors in the Rear and One Steering Dc Motors in the front ...
the old circuits contain just 2 H-bridge for 2 Dc motors, when i test it one H-Bridge is Burned out cause i connect it to 2 Rear Dc Motors, So i figured out that i have to add a new H-Bridge to my second rear Dc Motor ... The demodulator is a chinese clone of the RX-2 Chip ... When i tested it's output i found that it output pulses (when i trigger forward it generate a positive pulse ... and when i release the forward trigger, it generate a negative pulse ) and with this pulses it make the DC Motors Runs .... So i searched in the Internet and i figured out that it could be a latching circuit after this pulses ... However when i retrace the Circuit i did not found any LAtching Circuit ... So this is my problem and i want someone to tell me how this thing "Chinese RX-2 Chip" control the DC motors with Pulses ?????

*******************

-------------------------


*******************
You will Found in the attachement the circuit schematic of the H-Bridge

*******************
Here is a video about the result of the oscilloscope in the output of the left and right ouptut pin signal
https://sendvid.com/hguz65wg

*******************
So i want to know how this thing make a dc motor turn on ??
How could i make another H-Bridge that trigger on with this kind of pulse for my Third DC Motor ??
Thx ??

 

Thanx for your explanation, but when this MOD function is High when it is connected to ground or to Vcc ? , also "the function is latched" means that it will output a straight signal let say constant 3volt ??? Thx