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Author Topic: A little help with a blinking m-unit  (Read 834 times)

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Offline gjunkie

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A little help with a blinking m-unit
« on: May 23, 2018, 12:20:31 PM »
Hi there!

I’ve been searching everywhere I can for help on this but can’t find a straight answer. Hoping someone here can educate me a bit.

I have a ‘75 CB400F. I rewired it with an m-unit and has worked great. Recently I removed some unused wires and replaced a few bad ones. The bike has sat around for a couple of years without use (sadly). Now when turning on power I get two blinking lights: Light In and Break In. So as per the troubleshooting directions I figured I had a bad connection. Here’s he kicker.. after debugging for a while I tried to go back to basics and disconnected both of these systems... the lights still blink.

I’m curious if this means one of the following: I have to reset the m-unit, I have a bad m-unit, I truly have a short somewhere and either it or I am confused....

Any help is appreciated. Thanks!
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Offline calj737

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Re: A little help with a blinking m-unit
« Reply #1 on: May 23, 2018, 01:39:40 PM »
Typically an indication of a very bad ground, or, a very weak battery. Does the engine fire?
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"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline piefairy

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Re: A little help with a blinking m-unit
« Reply #2 on: May 23, 2018, 04:20:11 PM »
When I was initially setting up my M-unit, I attached the ground battery terminal directly to the unit to eliminate as many variables as I could trying to cut out variables. But Cal is the expert, he helped me with mine. I just tried to not seem like a complete idiot  ;D
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Offline calj737

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Re: A little help with a blinking m-unit
« Reply #3 on: May 23, 2018, 04:52:22 PM »
Quote from: piefairy on May 23, 2018, 04:20:11 PM
When I was initially setting up my M-unit, I attached the ground battery terminal directly to the unit to eliminate as many variables as I could trying to cut out variables.
That is not a recommended configuration. The battery needs to ground the frame and motor. The M-Unit wants a solid path to ground, best if through the chassis.
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'74 550 Build http://forums.sohc4.net/index.php?topic=126401.0
'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline piefairy

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Re: A little help with a blinking m-unit
« Reply #4 on: May 23, 2018, 07:05:00 PM »
Quote from: calj737 on May 23, 2018, 04:52:22 PM
Quote from: piefairy on May 23, 2018, 04:20:11 PM
When I was initially setting up my M-unit, I attached the ground battery terminal directly to the unit to eliminate as many variables as I could trying to cut out variables.
That is not a recommended configuration. The battery needs to ground the frame and motor. The M-Unit wants a solid path to ground, best if through the chassis.

At the end of the day, I agree, but it was a temporary setup to ensure a good connection for testing. There was a cable to the chassis as well as a cable to the neg of the m-unit, just to ensure a solid connection.
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