Cmax Required System Reboot: Modules All Rebooted & now Fixed, Have questions

[stratosurfer]

I’ve decided to put this discussion under general because it hits many topics. I got locked out of my C max Thursday of this week and the car would not recognize my fob my backup fob which I keep hidden on the vehicle disassembled, nor would it recognize the fobs with brand new batteries put in them. I use the blade key to get into the car and follow the procedure in the manual to put the fob next to the RF emergency receiver on the steering column followed the procedures in the manual hit the brake, hit the start button and she lit off. Once started I went ahead and drove about 20 miles home and received interesting error codes on the dash, such as approaching exceeding maximum speed… There were other quirky issues going on such as the electric liftgate would go up but not come back down. If I closed the door when I got out it would not recognize the fobs and I would have to put the fobs right next to the emergency receiver on the column to start and then could again drive the car, but it was apparent that a module was having multiple faults setting off multiple problems. After reading through a few of the forums here I made the decision to unbury the 12 V battery in the rear compartment and to disconnect the 12 V lead. After disconnecting the 12 V lead and leaving it disconnected for at least five or 10 minutes I reconnected it and went in and started the car and now everything works. This has been two days of driving now and I’ve had no fall back to any of the old problems, I have left that rear facia piece of plastic of the rear covering over the battery compartment off in case something else went wrong. I must mention I replaced the OEM 12v battery about three or four years ago With an odyssey AGM battery. My plan now is to install a 12 V disconnect switch via two 3 foot battery lead pigtails from the positive terminal and place the battery disconnect in the little ventilation access compartment on the right side of the trunk compartment for easy access. Should I have another situation like this I will be able to enter the car via the blade key follow the procedures get the hatch opened and disconnect the 12 V battery from a disconnect switch that’s very easily accessible by that air ventilation panel on the right. I won’t have to get somewhere and get the tools to remove that plastic piece for access to the 12v battery.

Sorry for this long post but I felt it needed the details to be able to explain all that’s going on in my proposed solution. I discussed my problem with a factory Toyota mechanic friend with and he said it was standard operating procedure in problems like these with his training at Toyota to do exactly what I did and pull that positive lead off and allow these modules to reset themselves and essentially reboot the entire system.

I have a question: if anyone knows what gauge those 12 V battery leads are? I found some four gauge battery leads and I don’t know if that is thick enough. I do know that the battery leads from the 12 V battery are only powering the electronics suite, they don’t look all that thick. 

If anyone knows the spec on the 12V leads would you please let me know. I will report back on how things go after this reboot of all the modules and how the remote battery disconnect mod works out.

Thanks

Mark

[homestead]

What voltage was the 12V battery at?

[stratosurfer]

On 8/27/2022 at 11:48 AM, homestead said:

What voltage was the 12V battery at?

I didn’t test for the system came right up. I forgot to post I did check the fuse at the 12V terminal with an IR tester and it appears good.

Edited August 27, 2022 by stratosurfer

[cr08]

Having messed with this a bit in my recent inverter setup, I can say the big negative battery lead going from the battery to the bolt on the body middle-ish of the car back there is probably around 4ga. Visibly it's about the same gauge as the wire I used which is also 4ga.

 

Can't say for the positive side since that one's not as straightforward. The main battery fuse/junction on the positive terminal of the battery actually splits right there between the DC-DC converter and vehicle electronic feeds.

 

There's also plenty of resources/tables around the net detailing correct wire gauge sizing based on load and wire length. Nothing special needed for a hybrid vehicle here, the same concept applies.

 

That said, if this was my own vehicle I'd focus on trying to fix the actual cause of your issues than a bandaid such as this. But that's me. Most of the common causes of issues like random battery drains or fob detection issues are well known and have solutions.

Edited August 27, 2022 by cr08

[stratosurfer]

On 8/27/2022 at 5:22 PM, cr08 said:

Having messed with this a bit in my recent inverter setup, I can say the big negative battery lead going from the battery to the bolt on the body middle-ish of the car back there is probably around 4ga. Visibly it's about the same gauge as the wire I used which is also 4ga.

 

Can't say for the positive side since that one's not as straightforward. The main battery fuse/junction on the positive terminal of the battery actually splits right there between the DC-DC converter and vehicle electronic feeds.

 

There's also plenty of resources/tables around the net detailing correct wire gauge sizing based on load and wire length. Nothing special needed for a hybrid vehicle here, the same concept applies.

 

That said, if this was my own vehicle I'd focus on trying to fix the actual cause of your issues than a bandaid such as this. But that's me. Most of the common causes of issues like random battery drains or fob detection issues are well known and have solutions.

It didn’t throw any codes, what can be done to track down an issue with no codes thrown?

[SnowStorm]

On 9/3/2022 at 3:35 PM, stratosurfer said:

It didn’t throw any codes, what can be done to track down an issue with no codes thrown?

What did you use to check for codes?  Its my understanding that using Forscan can find codes that other methods won't (I suppose, more Ford specific ones).  Should you find codes associated with a particular module, you might try unplugging/re-plugging its connectors a couple of times.

 

AGM batteries require a different charging profile so yours may not be getting maintained properly.  I suggest checking the voltage occasionally to see how it is doing.  Of course this check must be done before turning the car on because the HVB and DC-DC converter will start charging the 12V battery at that point.

[stratosurfer]

On 9/7/2022 at 9:05 AM, SnowStorm said:

What did you use to check for codes?  Its my understanding that using Forscan can find codes that other methods won't (I suppose, more Ford specific ones).  Should you find codes associated with a particular module, you might try unplugging/re-plugging its connectors a couple of times.

 

AGM batteries require a different charging profile so yours may not be getting maintained properly.  I suggest checking the voltage occasionally to see how it is doing.  Of course this check must be done before turning the car on because the HVB and DC-DC converter will start charging the 12V battery at that point.

I use Blue Driver scanner and it isn’t as deep as FORScan, but pretty good. Anyhow, I wanted to report back that I’ve had zero problems since I rebooted all modules after disconnecting my negative terminal on the 12V battery.

[jzchen]

On 11/24/2022 at 4:26 AM, stratosurfer said:

I use Blue Driver scanner and it isn’t as deep as FORScan, but pretty good. Anyhow, I wanted to report back that I’ve had zero problems since I rebooted all modules after disconnecting my negative terminal on the 12V battery.

Thank you for coming back to update your thread!  I'm glad to see a "reboot" has solved your issue.  The C-MAX has a lot of electronics in it that's akin to being a computer.  Sometimes a random bug may creep out like you experienced.  From my experience the car will warn you on screen when the battery has become weak/time to replace.  So since you didn't report that I'm betting your battery is still good, and you just got one of these random bugs...

[stratosurfer]

On 11/24/2022 at 5:54 PM, jzchen said:

Thank you for coming back to update your thread!  I'm glad to see a "reboot" has solved your issue.  The C-MAX has a lot of electronics in it that's akin to being a computer.  Sometimes a random bug may creep out like you experienced.  From my experience the car will warn you on screen when the battery has become weak/time to replace.  So since you didn't report that I'm betting your battery is still good, and you just got one of these random bugs...

Agree. I put in an Oddyssey battery when the OEM battery failed years ago. These Oddyssey batteries last a long time. I’ve had zero problems since the battery disconnect reboot.