Troubleshooting: 1115 & 1116 alerts

[gregd]

I've been getting an increasing number of 1115 and 1116 alerts with the hotter weather. They relate to the motor temperature sensors, reporting that there's some sort of mismatch in their readings. I presume it's time to do the "annual" maintenance cleaning, which I did myself (for the first time) over the weekend. Indeed, the motor fins were pretty well packed with leaves and other debris, and that got all cleaned out.

The car drives fine (it always has), but the 1115 / 1116 alerts remain. They are visible in the logs, and via the OVMSv3 module.

Besides the cleaning around the fins with a shop vac and air compressor, is there anything else I may have missed, for example a loose electrical connector or something related to the sensors themselves? Did I somehow not clean things well enough?

The issue was happening a number of years ago, and it was resolved during an annual service by the SC but they didn't indicate any particular fix being applied. Prior to the service, a discussion with the lead technician (one of the original Roadster techs) suggested that the sensors were internal to the motor, and the "only" way to fix them was to replace the entire motor. We didn't do that, but something else resolved the issue.

What is the root cause and proper fix?

 

[ML Auto]

Response as to possible solution posted in the PEM cleaning thread.

 

[gregd]

Reviving this thread... The de-leafing was done a few months ago, but the 1115 / 1116 alerts remain. Yesterday, on a relatively calm drive through town, I got a Power Limited event 1070 - "DMC FW: Motor sensor 2 OverTemp warning. Torque limited". It was certainly warm out, but after only a few miles of city driving there's no way the motor was actually that hot. Regular performance returned after a few seconds of very limited (and oddly erratic) power. I presume there's a loose wire or connector somewhere.

I've seen the wiring diagrams in the service manual set that was posted earlier, but can't quite grok where Motor sensor 2 is, or how the wires from it reach the PEM. Does anyone know which connector might be at fault?

 

[JaxonDM]

Have you cleared those alerts already? My friend is looking at this 2011 Roaster with the same alerts, intermittently. Sometimes they flashes at city driving but mostly driving just fine in long drives. It's neat overall with a new set of tires from 4Wheelonline installed last month.

 

[gregd]

Have you cleared those alerts already? My friend is looking at this 2011 Roaster with the same alerts, intermittently. Sometimes they flashes at city driving but mostly driving just fine in long drives. It's neat overall with a new set of tires from 4Wheelonline installed last month.

The alerts are still happening, though less with cooler weather. They are related to the motor temp sensors, so really depend on how I drive. If it's a loose connection (my suspicion), the temp effect might be the connector itself making better / worse connection under different conditions. I just don't know where to look...

 

[spaceballs]

I've had higher PEM/motor temps due to fan blowers bearings going bad (as they spin slower) and got PEM temp errors. Also I could notice it when charging that the blower fans were making louder noises/spinning slower. After replacing the fans I no longer saw the temp issues.

 

[gregd]

I've had higher PEM/motor temps due to fan blowers bearings going bad (as they spin slower) and got PEM temp errors. Also I could notice it when charging that the blower fans were making louder noises/spinning slower. After replacing the fans I no longer saw the temp issues.

Yeah, thought of that, but looking back in the logs I see that this car has had the issue on and off for many years, going back well before I owned it. I've also rebuilt the wiring harness going between the PEM and fan blower motor, which solved the 1144 / 1146 errors. The PEM itself hasn't had issues with high temps.

Key symptom here is the "ability" of the motor to change temps from normal to hot and back over a period of a few seconds. FAR too much mass for it to do that, especially when the car is sitting at a stoplight and not even moving. Definitely an intermittent sensor.

I'm guessing that an incorrectly hot reading would be a shorted connection, either across the sensor or perhaps between one lead and chassis ground, as opposed to an open / loose connection. Where would I look? Where is this wiring?

Given the car's history with this problem, is there a way to disable or ignore the errant sensor? For example, could I wire the one good sensor to both PEM inputs? Or would that double (or halve) the resulting reading? It appears that the only alternative is to replace the entire motor.

 

[spaceballs]

"I'm guessing that an incorrectly hot reading would be a shorted connection, either across the sensor or perhaps between one lead and chassis ground, as opposed to an open / loose connection. Where would I look? Where is this wiring?"
If i remember right there are two temp sensors, same connector that go to the motor encoder. maybe Pin 3/12 and 4/13 for the two sensors.

 

[gregd]

"I'm guessing that an incorrectly hot reading would be a shorted connection, either across the sensor or perhaps between one lead and chassis ground, as opposed to an open / loose connection. Where would I look? Where is this wiring?"
If i remember right there are two temp sensors, same connector that go to the motor encoder. maybe Pin 3/12 and 4/13 for the two sensors.

Two sensors, correct. #2 is the problem one for me. Where is this magical connector?

 

[spaceballs]

Under the PEM.

 

[gregd]

Ooh, excellent. That one is accessible without pulling the car apart.

On the motor end, any idea where that connector is?