Rocket 3 ems relay drains battery and bike won’t start

Kevin frazier said:

.... With the key off voltage at ems relay is 12.6 on the 2 big wires and 11.7 on small yellow wire ground reads 11.7mv,

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with key on readings are the same and with kill switch hit to off no changes same volts,

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Kevin frazier said:

To add to this question key off volts 12.70 key on 12.43 30 seconds 12.34 and 1 minute 12.34,

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DEcosse said:

That suggests that the ECU is enabling the Relay to be ON (via that Yellow/Grey wire) even when the Ignition Circuit is not powered!
Is this immediately after turning ignition key off, or do you get the same thing if you just check it cold (without attempting to turn it on again) maybe 15 mins (at least) later?

What you need to do is check to see what the voltage is on the ignition circuit -
Check voltage at Fuse #5*
a) with key off - Kill-Run in Kill
b) with key on - Kill-Run still in Kill
c) With Key on, Kill-Run in Run
d) with Key OFF, Kill-Run in Kill

* Note that you do not have to remove the fuse - touch the meter positive probe to one of the metal tabs on the top of the fuse.

This will help to determine if you have a key-switch problem (or some other short on the ignition circuit) or a faulty ECU.




Can you confirm that the headlight is on when you take the key-on measurements?
(If so that is actually quite good - I would say surprisingly good actually)

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Kevin frazier said:

headlight is on I’m gonna go check those readings at fuse #5 thanks a lot for your help

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Kevin frazier said:

A.Key off kill on 7.2mv, B.key on kill off 11.9v C. Key on kill off 11.87v D. Key off kill on 13.5mv

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Kevin frazier said:

I wrote it wrong but the numbers coincide with the question a.b.c.d. as you asked

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Kevin frazier said:

I wrote it wrong but the numbers coincide with the question a.b.c.d. as you asked

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Kevin frazier said:

Ran test again and d key off and in kill was 7.2 like a

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Kevin frazier said:

Start switch maybe? Because when I toggle the kill and hold start switch it attempts to fire up, but ecu sounds like culprit because of battery drain also. I bet you’re right. Do you think I should buy a used ecu say from pinwells or order new. If you’re ever in Nashville I owe ya, thanks so much for helping me

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Kevin frazier said:

Start switch maybe? Because when I toggle the kill and hold start switch it attempts to fire up, but ecu sounds like culprit because of battery drain also. I bet you’re right. Do you think I should buy a used ecu say from pinwells or order new. If you’re ever in Nashville I owe ya, thanks so much for helping me

Click to expand...

DEcosse said:

That suggests that the ECU is enabling the Relay to be ON (via that Yellow/Grey wire) even when the Ignition Circuit is not powered!
Is this immediately after turning ignition key off, or do you get the same thing if you just check it cold (without attempting to turn it on again) maybe 15 mins (at least) later?

What you need to do is check to see what the voltage is on the ignition circuit -
Check voltage at Fuse #5*
a) with key off - Kill-Run in Kill
b) with key on - Kill-Run still in Kill
c) With Key on, Kill-Run in Run
d) with Key OFF, Kill-Run in Kill

* Note that you do not have to remove the fuse - touch the meter positive probe to one of the metal tabs on the top of the fuse.

This will help to determine if you have a key-switch problem (or some other short on the ignition circuit) or a faulty ECU.




Can you confirm that the headlight is on when you take the key-on measurements?
(If so that is actually quite good - I would say surprisingly good actually)

Click to expand...

DEcosse said:

So your ignition circuit is definitely not on
If you still get 11.7 on the yellow/grey wire (& relay is on) with the key &/or kill off then ECU must be bad- do make sure you are not checking immediately after key off though, as it will take a delay before the ECU normally turns off the EMS control signal
But if it never goes off, then must be ECU issue (what is odd though is where the supply voltage can be coming from with ignition circuit off)

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