search sucks! how do i make the ecu cel tester thinga majig

 

It doesn't work for the VTEC solenoid. YOu actually need to test it in the car. It only really works to see if there is not a solid cel. I had an ecu that would always throw code 9. Tester didn't pick it up, since the ecu doesn't look for the sensors in the dizzy until the engine is running.


Look at the plugs from the wire side.

It goes from left to right, A B D for the plugs.

Then the numbering of the pins is like this:

1 3 5 7 9 11 ......
2 4 6 8 10 12......


D4 and B2 to (-) on 9 volt

LED+ and A25 to (+) on 9 volt

A13 to LED-


If the LED doesn't light, flip it around. Or you could always use a light bulb.

NOTE: The ecu outputs the code in reverse. When the light is on or low light, it really means that the CEL is off. So you count the offs or low light pulses.


That is it.

 

the one i made does the blinks in reverse also but i just figured i had the LED backwards. i had a diagram showing how to wire it up that i had posted somewhere on here, i'll try and find it.

 

https://www.homemadeturbo.com/forum/...4277#msg724277

looks like my picture was deleted

 

LEDs don't work with the current reversed.


On a high pulse there is some voltage, around 2 or so.

A low or off pulse goes up to battery voltage.


A simple BJT could be biased correctly and have the output correct with the light on the dash.

I might make one tonight at work and post it.

 

dont LEDs have to have resistors to work correctly? maybe thats why the light barely flashes. why not use a bulb like the one in the back of the gauge cluster itd be a lot easier to see the blinks no?

 

LEDs need a resistor in series to limit the amout of current passing throught them. Typically the current required for the LED depends on the size and the color. Higher frequency colors require more current.

Having no resistor wil make the LED really bright and at 9 volts it would probably fail right away.

470ohm resistor with 9 volts is fine. That'll give you 19ma to the LED, but make sure to use a 1/4 watt resistor as you are going to have around 160mW throught the resistor.



I did some more testing.

With the CEL on, the pulse is slightly below battery voltage.

With the CEL off, the pulse is about half battery voltage.

 

the LED i used is one o fthose blue ones form radio shak and works great with the exception of the reverse blinking. but its bright and you can see when it is a blink or not.