main relay not energizing when key is turned on

[captainj]

2002 dx150tlra ox66. The relay has a constant hot(12v) red wire coming from the 30amp fuse, and a blue/yellow stripe that energizies the relay. The blue/yellow goes straight to the ecu which I think that the ecu should ground. If I ground the blue/yellow the main relay energizies like it should and make the red/yellow hot for the fuel pump ect. When I ground the blue/yellow the fuel pump runs like it should and turns off like it should. There are not trouble codes.
Should the ecu provide the ground? What tells the ecu to ground this?
What do I need to check, is the ecu bad.
Rodbolt you out there you seem to be the genius?

[boscoe99]

A yellow wire (battery power from the key switch) tells the CDI that the key is in the on position. The CDI getting 12 volts via the yellow wire tells the CDI to ground the main relay control circuit. The main relay control circuit being grounded causes electrical power to be provided to the fuel pump and other components.

Check the yellow wire to the CDI for the presence of battery voltage when the key is in the ON position.

Our resident genius may be along shortly with further information.

[captainj]

The yellow wire does have 12v on it.
Thanks for helping.

[boscoe99]

The yellow wire does have 12v on it.
Thanks for helping.

Yes, but is the voltage actually getting to the CDI? Did you measure voltage on the pin/socket that connects directly to the CDI? Could possibly be a connectivity issue right at the pin/socket interface. Sometimes simply removing and reinstalling a connector several times will improve the connectivity such that what did not work now works.

Also, make sure that the ground to the CDI is clean and secure.

[captainj]

There is 12v all the way to the pin on cdi. Unplugged several times. Still not working.
Thanks

[captainj]

Any more suggestions, anyone?
Boscoe99 thanks for your help. Do you think it is the cdi?
They are just so expensive. I will just bypass that leg of the cdi. I will take the constant 12v off the relay and use switched yellow 12v to the relay and provide my on ground. What do think about that?

[ausnoelm]

Locate the earth from the CDI, you have confirmed it is being supplied 12V (well, you said you did) and you are testing that 12V from another earth point....

[captainj]

There is 2 ground wires coming out of the top of the cdi. I disconnected the ground wires from the engine. Then I tested the 12v yellow to each of the ground wires and they both showed 12v coming out.

[boscoe99]

Any more suggestions, anyone?
Boscoe99 thanks for your help. Do you think it is the cdi?
They are just so expensive. I will just bypass that leg of the cdi. I will take the constant 12v off the relay and use switched yellow 12v to the relay and provide my on ground. What do think about that?

Try it and see if the motor runs.

[ausnoelm]

There is 2 ground wires coming out of the top of the cdi. I disconnected the ground wires from the engine. Then I tested the 12v yellow to each of the ground wires and they both showed 12v coming out.

So, where the two ground wires actually grounded when you did the test? As Rodbolt has explained countless times, you need to remember that the 12V is constant, only the ground is switched, don't bamboozle yourself.

[rodbolt17]

now that you have seemed to determined you have 12V to the ECU, do you have a ground path from the ECU to the relay ?

[boscoe99]

So, where the two ground wires actually grounded when you did the test? As Rodbolt has explained countless times, you need to remember that the 12V is constant, only the ground is switched, don't bamboozle yourself.

In the vast majority of instances this is correct.

However, there are a number of Yams where the 12 volt positive is switched. In the OP's motor the CDI is grounded to the block. The electrical power to the CDI is provided by the key switch.

[boscoe99]

now that you have seemed to determined you have 12V to the ECU, do you have a ground path from the ECU to the relay ?

The OP says "If I ground the blue/yellow the main relay energizies like it should and make the red/yellow hot for the fuel pump ect."

I assume this means that he grounded the wire that runs from the CDI to the relay control circuit (at the CDI) in which case the ground path from the CDI to the relay is confirmed to be good.

Am I an ass for making that assumption?

I don't see a blue/yellow wire as being part of the relay control circuit but he says when that wire is grounded the relay closes.

Hard to trouble shoot from a distance ain't it?

[captainj]

Thanks everybody
On the main relay itself has 2 wires that energize the relay they are yellow and black. The wiring harness has constant 12v red wire that pins to the yellow and blue/yellow that pins to the black wire of the relay. The blue/yellow wire goes directly to the cdi. There is no splices or connection on the wire. The blue/yellow is L/Y on the yamaha manual wiring diagram. It does match the way the engine is wired. So not sure why it doesn't match your wiring diagram.
Continuity is good on the blue/yellow wire. If blue wire is grounded at the cdi it will close the relay and everything works. The engines starts and runs good.
The cdi does supply ground for the high pressure fuel and shifts ground from resistor when above idle

[boscoe99]

Thanks. Bad wiring diagram on my part.