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Pulling diagnostic codes

 
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mukaiboston
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Joined: 06 Sep 2010
Posts: 287
Location: Washington, DC
Green Buddy 170i "Annie-Jade"

PostPosted: Mon Jun 29, 2020 7:48 pm    Post subject: Pulling diagnostic codes Reply with quote

I'm having a hard time obtaining a diagnostic tool to pull the error codes out of the ECU. Someone told me I could jump the pins to get a read out. I'm thinking of using an LED or a multimeter, but I cannot do this if I don't know what pins to jump or what each pin does and the schematic is not in the service manual.

Does anyone know where to obtain this information? I believe the Buddy and the Blur both use the same data port.


Basically, the engine light comes on before I even hit the ignition. Idle is really rough with occasional misfiring, some hesitating and some engine surging.

Mechanic inspected for vacuum leaks and says there's nothing that can be done without the error codes otherwise you end up replacing sensors and computer parts in the hopes that something fixes it. This isn't economically viable. For all I know the main computer (ECU) could be broken and that's a $600 part right there.

The best I can hope for now is to manually check as many sensors as possible for resistance and voltage, but what I really need are the computer error codes.
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mukaiboston
Member


Joined: 06 Sep 2010
Posts: 287
Location: Washington, DC
Green Buddy 170i "Annie-Jade"

PostPosted: Mon Jun 29, 2020 8:07 pm    Post subject: Reply with quote

I'm not an electrician, but here is the basic rundown of what I've been doing.

Each sensor will have some number of pins. One is a ground pin and the others could be data pins (marked as "output" on the diagrams) or power input pins (which delivers electricity to activate the sensor).

You have to use the service manual to get the pin definitions. Otherwise, I think there are ways to guess, but you have to know what you are doing so you don't short anything out.

To test if the sensor is working properly, I've been trying three things:

==
1) Test for resistance.
==
a. I set the meter to Ohms and make sure the sensor is unplugged and is not connected to any electrical source (important!)

b. Put the positive lead on the data pin and the negative lead on the ground pin. The meter should change from a "1" or "infinite" to some digit.

c. Perform an action to make the sensor operate and watch to see if the digit changes. So for a throttle position sensor, you have to open the throttle. For a temperature sensor, you would have to stick the sensor in ice water and then boiling water. For something like the MAP sensor or Idle Control Sensor, I'm not sure you can do this part since the engine would have to be running.

==
2) Test for power
==

a. I set the meter to measure voltage and stick the positive lead into the hole of the port connected to the scooter for the electrical input and stick the negative lead of the meter into the ground hole of the port.

b. I turn the scooter key to the on position and see what voltage measures. For some ports it will be 5v and others 12v usually but you have to check the diagrams. This means that electricity is going from the scooter's computer to the sensor.

==
3) Test for correct voltage signals
==

This is the hardest one and I actually have not succesfully been able to do this. What you have to do is "backprobe" the plug as it is connected to the sensor and then turn the scooter on or start the engine depending on what you want to test.

You have to perform the action to make the sensor work and then read the voltage outputs and make sure they match what is in the service manual.

So for example, if you are testing the throttle position sensor, for my scooter the voltage from the data pin should be something like 0.8v when the throttle is closed and 3.8v when the throttle is wide open.

--
If these test check out, then you can conclude the sensor is functional; however, this isn't really a replacement for getting the diagnostic codes since what's wrong might not even be a blown sensor. But it's what I'm trying to do since it is my only option.
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