Disengaging the electronic parking lock

[nick]

Any tricks to disengaging the electronic parking lock on a dead 1.5 Roadster? (my Roadster is fine, this is another one)

I patched a 12V battery into things and the car booted up... the screen would go into Tow Mode but there was no thunk and after a few attempts it reporting a parking system failure.

If anyone has a page from the service manual that would help please let me know... I plan to drop the bottom panels tomorrow to see what is accessible.

 

[supersnoop]

Any tricks to disengaging the electronic parking lock on a dead 1.5 Roadster? (my Roadster is fine, this is another one)

I patched a 12V battery into things and the car booted up... the screen would go into Tow Mode but there was no thunk and after a few attempts it reporting a parking system failure.

If anyone has a page from the service manual that would help please let me know... I plan to drop the bottom panels tomorrow to see what is accessible.

Navigating to the Tow Mode setting is all the manual describes.

 

[nick]

Navigating to the Tow Mode setting is all the manual describes.

Hmmm... that suggests either the parking lock is on the other 12V circuit or the parking lock on this car has seized.

 

[ML Auto]

The parking lock mechanism is controlled by the PEM thru the CAN bus, so you can't just apply 12V to it to get it to operate. I have found the easiest way to push a bricked car around is to remove an axle.

 

[nick]

The parking lock mechanism is controlled by the PEM thru the CAN bus, so you can't just apply 12V to it to get it to operate. I have found the easiest way to push a bricked car around is to remove an axle.

Well that complicates things.

I guess I could power up the PEM with a 400V bench power supply after disconnecting the battery (along with supplying 12V to the car like before)

 

[gregd]

Well that complicates things.

I guess I could power up the PEM with a 400V bench power supply after disconnecting the battery (along with supplying 12V to the car like before)

I think the nominal ESS voltage is 375 (vs 400), no? Still, you have a 400v bench supply?

 

[ML Auto]

I would assume since the 12v power to operate to parking lock comes from the APS (which is powered from the 400v ESS), the locks operation is disabled unless the ESS has the required voltage.

 

[ShawnA]

Hi Nick,

When I had a bricked battery the technician used a motorcycle battery.
He stripped a wire going to the electromagnetic parking pawl, used his motorcycle battery,
and the parking pawl released.

Good luck, Shawn

 

[nick]

Thanks - I appreciate the info!

The car is currently off site and stuck on a trailer. The 400V bench power supply won't arrive for another week.

I should be able to use a jack and drop the rear pan while still on the trailer... is that enough to get to the wiring or is it way up in there?

 

[ShawnA]

Hi Nick,

It has been 2 years since he did it but I think you should be OK.
I think the wire was located close to the rear left (driver's side) wheel well...
If you are able to find the electromagnetic lock, track down the wire
coming out of it. Too bad we don't have any kind of diagrams to help.

Good luck! Shawn

 

[nick]

There is a "transmission control" module under the car. One connector has CAN bus so that is obviously the input side. The other connector has 7 wires...

 

[nick]

Green wire + Green-white wire seem to be shorted.
Blue wire + Blue-white wire seem to be shorted.

Green to Blue is about 30k Ohm which is too high for a motor.

Other wires don't seem to be interesting.

 

[nick]

Figured it out... the control module is really just a fuse and CAN termination back from the gearing-box... looks like it is CAN all the way inside the gearing box.

Will try injecting power here to see if tow mode will engage from the LCD.

 

[nick]

Got the car rolling!

I wrote up my notes here:
Tesla Roadster – Transmission lock

Used two 12V batteries - one to power the main 12V system via the ABS fuse and the other to power the backup 12V system via the transmission fuse. From there Tow Mode worked.

 

[petergrub]

the other to power the backup 12V system via the transmission fuse.

You mentioned in the article on your website, "Step 2 = power up the backup 12V power with a second 12V battery… (if you know of an easier access point to this rail please message me)…".

That other rail should be accessible from the RHC7 connector which splices into the 12V wires you bypassed. It has only one red wire and plugs into the battery on the right side adjacent to the mid-to-rear harness interconnection.