Roadster 12V system is down.

[petergrub]

Maybe unrelated but when I was having problems all my gearshift buttons also illuminated.

I believe you may be on to the issue here. The shifter buttons light up red usually when the PEM is not communicating on the CAN bus. That may be due to a missing connection to the CAN bus, or the PEM is simply not receiving power. When the PEM is not receiving power, then the TCM will also show up as not communicating.

@driver_EV, can you confirm the second error message after the SHFT: Warning Lost Comms DMC? Also, have you pulled the PEM APS plug, RHC33, to check if the terminals are moving freely? Those terminals have recessed on me in the past when you insert the connector and caused issues.

 

[driver_EV]

Check the connector and wiring under the high voltage disconnect plug on the drivers side of the battery (square black plug). That is where the 12V power is for the VMS.

Okay, will try to get to that one (I need to learn and have never looked at it).
It may be difficult at the moment, as I have the RH side of the car on jacks in the air with both RH wheels removed. It looks quite difficult to reach. I see two connectors in that area, have put my fingers on two of them? see photo

(-oops, I forgot to downsize this image)

 

[PV-EV]

I believe you may be on to the issue here. The shifter buttons light up red usually when the PEM is not communicating on the CAN bus. That may be due to a missing connection to the CAN bus, or the PEM is simply not receiving power. When the PEM is not receiving power, then the TCM will also show up as not communicating.

Your contributions really help tie it all together. Thanks

 

[driver_EV]

Random note... On my car (a 2.0), there's a 12v output from the main battery pack at all times, even when the car goes to sleep, believed to be generated by a DC-DC buried somewhere within. The little 12v battery up front is kept at a float charge of 13.8v from it.

What is your 12v battery sitting at?

Thanks for this reply, With the state the car is currently in, the 12V battery is not being supported with a float charge. After getting the car "woke" again by applying external 12V at the APS terminals near/in front of the RH tire, and turning the key on, seeing normal dash lights, VDS, etc, I moved the known strong 12V battery to the front battery terminal connections.

I have a method to monitor DC current in/out of the external battery, and have a decent Fluke meter with min/max monitoring. What I am observing is that once the APS times out and things shut down, the car transitions to putting a load on the 12V battery, instead of giving it a float charge.

I am seeing on the order of .3A drain (or more at times) on the 12V battery taken by the car. Voltage is dropping steadily over an hour. Photos shown to indicate recent Max, Min voltages as the battery is being discharged.

While in this state (draining the 12V battery) the car is unresponsive, no doors unlock, VDS is off.
12V system power is down again.

The Fluke is connected directly to the battery terminals from the car for voltage measurement.

 

[driver_EV]

I believe you may be on to the issue here. The shifter buttons light up red usually when the PEM is not communicating on the CAN bus. That may be due to a missing connection to the CAN bus, or the PEM is simply not receiving power. When the PEM is not receiving power, then the TCM will also show up as not communicating.

@driver_EV, can you confirm the second error message after the SHFT: Warning Lost Comms DMC? Also, have you pulled the PEM APS plug, RHC33, to check if the terminals are moving freely? Those terminals have recessed on me in the past when you insert the connector and caused issues.

Thanks for this reply.
I will begin study of these.

The SHFT messages seem to always come in a simultaneus similar pair with ID:3004 and ID:3003 based on the recent alerts in VDS. The one displayed stays up for just a few seconds then can't be recalled. I am pretty sure the second error message is for the 3003 ID.

I need to determine the RHC33 identifier, If that is the 2 wire PEM/APS connection on the RH side of the PEM, I have inspected that one. Although the two pins look pristine, I have unfortunately broken the rubber seal there, and ordered repair parts. No visible issue (electrical) with that connection.

I will have to look again, as I am not familiar with the recessing of terminals issue.

 

[petergrub]

The SHFT messages seem to always come in a simultaneus similar pair with ID:3004 and ID:3003 based on the recent alerts in VDS.

So you have error ID 3003 SHFT: Warning Lost Comms VMS and error ID 3004 SHFT: Warning Lost Comms DMC. Also, you can probably ignore that error ID 1554 as that typically shows up when booting up the 12V system.

Those two errors are both coming from the shifter which could indicate the shifter is having an internal problem, or the shifter's status messages aren't reaching the VMS to indicate all is well. I don't see the correlation to the 12V system issues though. I'll keep thinking about it and see what I can dig up.

I need to determine the RHC33 identifier, If that is the 2 wire PEM/APS connection on the RH side of the PEM, I have inspected that one.

That is correct.

 

[driver_EV]

So you have error ID 3003 SHFT: Warning Lost Comms VMS and error ID 3004 SHFT: Warning Lost Comms DMC. Also, you can probably ignore that error ID 1554 as that typically shows up when booting up the 12V system.

Those two errors are both coming from the shifter which could indicate the shifter is having an internal problem, or the shifter's status messages aren't reaching the VMS to indicate all is well. I don't see the correlation to the 12V system issues though. I'll keep thinking about it and see what I can dig up.


That is correct.

Thanks, I have some things to think about, and will have another look later today.

 

[ML Auto]

The car charges the 12V battery thru the switchback when the car is awake. The car will run and drive even without the 12V battery connected, so I not worry about that system. If you can back probe the brown/black wire at the connector I mentioned (bottom left in your pic-terminal #1), you should always see 12V. If you do not, your problem is inside the ESS. You can also access that circuit at the Tesla CAN diagnostic connector under the passenger side of the dash. It is the only brown/blk wire-all the rest are blue or red. If you do not see 12V there even after the car goes to sleep, that is where your problem is. You should be able to connect 12V there and get the car to drive normally. But you will still need to check directly at that connector on the ESS to rule out a wiring problem.

 

[driver_EV]

The car charges the 12V battery thru the switchback when the car is awake. The car will run and drive even without the 12V battery connected, so I not worry about that system. If you can back probe the brown/black wire at the connector I mentioned (bottom left in your pic-terminal #1), you should always see 12V. If you do not, your problem is inside the ESS. You can also access that circuit at the Tesla CAN diagnostic connector under the passenger side of the dash. It is the only brown/blk wire-all the rest are blue or red. If you do not see 12V there even after the car goes to sleep, that is where your problem is. You should be able to connect 12V there and get the car to drive normally. But you will still need to check directly at that connector on the ESS to rule out a wiring problem.

Thanks much for this info. Good specifics to check. I was trying to narrow down which module is responsible for float charging the 12V battery, figuring that device would lead back to an APS or ESS connection that I could pinpoint as a failure candidate.

Getting closer.

 

[driver_EV]

You should be able to connect 12V there and get the car to drive normally. But you will still need to check directly at that connector on the ESS to rule out a wiring problem.

Initial test at the end of the day points to no 12V provided on that wire. I will check again more carefully tomorrow.

Will get things powered up again tomorrow and see if a signal shows there at all.

Seems quite a shame for such a light weight 12V power output to be the failure that may call for an ESS service in the car.

It looks like this or a similar line really should be on all the time, providing memory power for some control devices in the car, keeping the 12V battery from getting pulled down, giving power for wireless unlocking of the car and such.

 

[driver_EV]

Had to do some local errands, no actual changes or tests done today, but am taking and studying more photos of the ESS connector and wires. I want to be sure I can see the colors and pin positions clearly for identification. I may pull the trunk tub and/or LH rear wheel to get better access for some work to come.

Thinking that if this is an ESS failing to provide the always on 12V "memory power", it may be worth considering putting another connector on that wire, and adding another battery in the back to provide that low power source. Anyone heard of this being done? I could add a battery with a small fused circuit and know that it is safe.

 

[driver_EV]

If you can back probe the brown/black wire at the connector I mentioned (bottom left in your pic-terminal #1), you should always see 12V. If you do not, your problem is inside the ESS. You can also access that circuit at the Tesla CAN diagnostic connector under the passenger side of the dash. It is the only brown/blk wire-all the rest are blue or red. If you do not see 12V there even after the car goes to sleep, that is where your problem is. You should be able to connect 12V there and get the car to drive normally. But you will still need to check directly at that connector on the ESS to rule out a wiring problem.

It looks like I have confirmed the ESS is not providing 12V on that connector pin#1 (at all).
So far it seems you are also correct that the car will be normal again (have not driven again yet) with an alternate 12V provided on that wire.

I see no indication that this wire is broken or shorted. The ESS seems to simply have failed on that one small function.

From what I can see the car has two "always on" power sources, one is the 12V battery we are all familiar with, and the other is the ESS pin 1 to the brown/black wire in the car.

So, now I need to decide now to replace the failed ESS pin 1 supply. Probably a bigger 12V battery to replace the existing one would be a good solution. I may need to have an improved monitoring of that battery's status, and perhaps a special charging method.

 

[PV-EV]

If the car will drive with a temporary 12v supply connected as MLAUTO mentions above, that rules out other problems. You don’t need to actually drive it, just make sure it will go into drive. Some information suggests the 12v power on J4 pin 1 originates not in the APS but in the BSM on the right side of the ESS. I’m not sure if that is accurate for a 2.5 but I think so. Others might know if the BSM is accessible without pulling the ESS from the car.

 

[driver_EV]

The car does shift properly, "drive" selection works. Errors previously seen have disappeared, as it seems they were only set when battery was used at the APS terminals. Just applying battery power at the brown/black wire returns car to to normal.

Plus, I am feeling much better now too.

 

[PV-EV]

Be aware you may be bypassing some safety features provided by the BSM (battery Safety monitor). Sure wishing others would pipe up. Spaceballs? Gruber?

 

[ML Auto]

That circuit is the backup power and has voltage at all times as stated. It just supplies power for memory uses and to allows you to wake up the car to turn the APS on. There is a small voltage converter inside the ESS which is probably what failed (maybe a fuse). But everything will require ESS removal and disassembly. There should be no problem connecting that circuit to the 12V battery to get the car to operate, just be sure to use a fuse at the battery.

 

[petergrub]

Be aware you may be bypassing some safety features provided by the BSM (battery Safety monitor).

I think he's actually re-establishing a safety feature that has failed. Sure the fix is simply a band-aid for the problem, so with that in mind you will need to drop the battery pack to determine the cause of the failure on the BSM board. There is a little 3A fuse on the BSM board that may have failed.

 

[driver_EV]

Update: I have some of the work completed to revive the car.
The 12V system is operational with a change to the previously used 12V battery up front, and a tap into the fuse box, running a wire from that to the newer larger 12V battery.

I have been using the Deltran Battery Tender LiFePO4 batteries for my 12V needs. From what I read they have battery protection and balancing inside the sealed case, and have not had one fail yet.

This 12V system issue in the Roadster would have been a good way to kill the small battery I had installed a few years ago, but inspite of being fully drained twice by the Roadster load, the battery self-protected pretty well as far as I can tell.
The ESS 12V power loss means the battery gets drained by other circuits in the car that normally would have ESS "trickle" power. My testing shows the car needs .3A - .5A at 12V from the ESS to sit quietly while parked and turned off.

 

[driver_EV]

I replaced the small battery with a larger one to help sustain the 12V circuits in the car, but also have to keep a Battery Tender charger connected overnight, to be sure to cover and support that ongoing ~.3A/.5A drain.

When the key is on, the ESS provides additional 12V power to the car, and that removes the drain from the 12V battery while the car is being operated.

 

[warden_clyffe]

as MLAUTO wrote before: yes, it's the switchpack underneath the dash-panel, charging the 12V aux-batt.
i can highly recommend you NOT to put just a bigger/stronger battery in your car wich maybe pulls eventually more current while charging, because those switchpacks are quite vulnerable and - besides expensive - a pain in the butt to change (you have to undo half of the dashboard).
when you buy a new 12V battery please contact Gruberpower, they have sufficient alternatives !

i had twice before a 12V failure on a roadster. one was similar symptoms as yours but easy to fix:
when i opened the pem, the red positive cable coming from APS-connector to the board (see pic) had dry solder and lost contact.



the other one there was a burned cap on the same board but in the powerline of the PEM-fan. that car didn't loose 12V but complete comms to the CAN-bus.

well, in my eyes that bloody Molex-12V-plug is a highly suspected candidate as well...

anyway, good luck !