How to build your homemade Speed Limit Defender

Write ups and tutorials for maintenance and modifications.

How to build your homemade Speed Limit Defender

Postby AvivB » Sat Sep 19, 2009 6:32 pm

This post is relevant for anyone who use JDM ECU and try to drive above 180Kph.

All what this device is doing is to divide by 2 the number of pulses the ECU gets from the speed-sensor (now the limit is at 360Kph :) ).

Here is the schema for anyone who want to build one (ON YOUR OWN RISK!):

And here how it looks when I build it my way (smallest as possible and covered with epoxy to be bullet-proof unit:

For ST18x:
The speed sensor signal comes on the blue with white strip wire.
The +5V sensors power is on pink with blue strip.
To install it, just cut the speed-sensor wire and install this unit in the middle.

Parts needed:
1x 74LS93
1x 2N3904 (or 2N2222) transistor
1x 1N4148 (or 1N914) diode
1x 1MΩ resistor
1x 10KΩ resistor

If you need any help, let me know.
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('92 ST182RC 1/1 :-) )
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Re: How to build your homemade Speed Limit Defender

Postby zf_165_gt » Tue May 04, 2010 12:19 am

thanks, great circuit, will be usefull on a lot of cars :)
1988 ST165 , clean body, broken engine since acquisition.
1991 ST185 JDM , CT26/CT20 hybrid,
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