MXR Negative Contact Relay Failure........

[OneLapper]

A fellow New Englander dropped off his '18 MXR for me to look at.

Problem: Bike does not go into "Drive" when start button is pressed.

Code: Bike Displays "Battery Negative Contactor Fail" on display

History: This may be the very last Code 36 bike that was fixed under warranty by Alta.

Observations: The bike makes the normal double click upon pressing the start button, then immediately a third click is heard.
The Bus voltage spikes to battery voltage, then immediately begins to fall to 0 voltage.

Problem as observed: The negative contact relay is not latching.

Fix: Pending

Any feedback from here welcome

 

[Redwolf]

 

[Rashid510]

@OneLapper - Sounds like the contactor is disconnecting due to possible detecting pre-charge not being happy. PM sent

 

[OneLapper]

Pictures added to original post

 

[OneLapper]

It appears that this bike will need a replacement BCU (Battery Control Unit), which is located under the top battery lid. We're not sure if the problem is with the contactor, or with a specific trace on the BCU. In either scenario, the BCU is a PCB (Printed Circuit Board) and the contactor is soldered to it. The plan is to locate a new or used BCU, reprogram the bike, get it running, then inspect the old BCU to see if we can identify the problem and fix it.

 

[OneLapper]

With the assistance of @Rashid510 we located a used R pack battery lid/BCU assembly. When the replacement BCU arrives I'll swap parts and follow up with the results!

Stay tuned in!

 

[Oded]

With the assistance of @Rashid510 we located a used R pack battery lid/BCU assembly. When the replacement BCU arrives I'll swap parts and follow up with the results!

Stay tuned in!

how did it go with the swap?

 

[OneLapper]

Still waiting on the parts to be shipped.........

On another note, I did get some quotes from Gigavac for the contactors. I am going to order a set for both R and A packs. I'll make an attempt at replacing the R pack contactors on the old lid. It appears the A pack contactors are easy enough to swap out, not the case with the R pack.

 

[Oded]

I see.
The contactors exact model for the A pack is -
P105-BDA

 

[Mark911]

Our GROM project had a similar problem. Just wouldn't stay latched. We got a low bus voltage message but that was not the case. Ended up just re-flashing the system and the problem went away. When in doubt, flash it out!!!!

 

[snydes]

When in doubt, flash it out!!!!

Nice! I vote this goes under your username

 

[OneLapper]

Our GROM project had a similar problem. Just wouldn't stay latched. We got a low bus voltage message but that was not the case. Ended up just re-flashing the system and the problem went away. When in doubt, flash it out!!!!

@Oded should have his cable in a few days if it didn't get hung up in import.

But I think his system is not totally dead, right?

 

[Oded]

Actually it is dead. At the moment I can't connect, charge or do anything else.
Thanks to the guys here I am pretty sure we'll get it up and going.

Meeting with a friend today for another resuscitation attempt.

 

[OneLapper]

Ooops, I meant "is dead".

Hopefully you can get some signs of life out of it

 

[OneLapper]

Here's the update:

I eventually sourced a replacement BCU/lid assembly from a former Code 36 bike. It took WAY longer to get in my hands than I ever thought it would. The fact is that the parts seem to be out there but people are reluctant to sell them.

I installed the replacement BCU/lid, reinstalled the battery, all was good and everything worked. I cleared the C36 warning, updated the firmware, and that's that! A fully functional MXR ready to rip up the track and woods again!

Super thanks to all the people behind the scenes that helped me get this part, and get it running, for the owner.

Now we are working on reverse engineering the original BCU. We need to make a tool to remove the PCB from the lid, then learn how to replace the contactors and reinstall everything. As a recap, this battery had a contactor problem. I'm hopefully that the contactors can be replaced and then this BCU can be used as a spare for someone else.

And now to move on to the next challenge.........

 

[Oded]

Here's the update:

I eventually sourced a replacement BCU/lid assembly from a former Code 36 bike. It took WAY longer to get in my hands than I ever thought it would. The fact is that the parts seem to be out there but people are reluctant to sell them.

I installed the replacement BCU/lid, reinstalled the battery, all was good and everything worked. I cleared the C36 warning, updated the firmware, and that's that! A fully functional MXR ready to rip up the track and woods again!

Super thanks to all the people behind the scenes that helped me get this part for the owner.

Now we are working on reverse engineering the original BCU. We need to make a tool to remove the PCB from the lid, then learn how to replace the contactors and reinstall everything. As a recap, this battery had a contactor problem. I'm hopefully that the contactors can be replaced and then this BCU can be used as a spare for someone else.

And now to move on to the next challenge.........

Thanks for the update.
I also think that repairing these BCUs should be a primary goal.
I suspect it's not that easy.

enjoy your new (?) bike!

 

[OneLapper]

Yes, repairing them needs to be a priority.

Oh, this isn't my bike. I fixed it for a local Alta owner just to be a nice guy. I didn't imagine it would take nearly two months!

 

[Redwolf]

I think I speak for all here when I say thank you for your time and energy to determine the repair procedure for our bikes, if the day ever comes that others will need repairs too.

 

[snydes]

I think our ability to work together to repair these bikes is good all things considered. We are fortunate to have several former Alta employees and some talented owners who are active in helping find solutions to the problems that come up in their spare time. At the time of this post I am not aware of any “bricked” bikes that have been reduced to donar bikes. This statistic helps prop up the value of our motorcycles and should be important to all of us. Eventually it will happen, either by lack of patience or lack of willingness to spend the funds, that a broken bike comes up for sale at a bargain price. For now I’m proud to say we’ve done our best to avoid that.

Patience and teamwork is critical!

 

[Oded]

I think our ability to work together to repair these bikes is good all things considered. We are fortunate to have several former Alta employees and some talented owners who are active in helping find solutions to the problems that come up in their spare time. At the time of this post I am not aware of any “bricked” bikes that have been reduced to donar bikes. This statistic helps prop up the value of our motorcycles and should be important to all of us. Eventually it will happen, either by lack of patience or lack of willingness to spend the funds, that a broken bike comes up for sale at a bargain price. For now I’m proud to say we’ve done our best to avoid that.

Patience and teamwork is critical!

Amen to that.

I can testify to that as someone who is going the exact same route with a malfunctioned bike at the moment. I get all the support & help I need from this group.
I am sure my bike will be fixed.

This is coming from someone who is on the other side of the planet (Israel).