Spark Max suddenly not receiving PWM signal after a firmware update

We have around 3 different Spark Maxes that we’ve tried, and all of them have exhibited the same problem:

When running on firmware version 1.4.0 (which is what they came with), they’ll work perfectly fine over PWM(although with a wrong PWM deadband). Since they’re out of date, the REV software forces you to upgrade the firmware before being able to change any parameters. However, after upgrading firmware, they absolutely refuse to receive any PWM signal. I’ve tried the PWM with Talon SRXs we have lying around, and those get the signal just fine. I’ve tested the Spark Maxes over CAN as well with the REV software over USB and they take a CAN signal fine, they just don’t seem to like PWM. All they do with a PWM signal is blink yellow, as if the signal wire is unplugged entirely. However, if I take the signal wire and plug it into another Spark Max, that one DOES accept signal! It’s extremely weird that 3 different Spark Maxes would have the same exact issue.

Some more troubleshooting that I’ve tried:

  • Downgrading the firmware
  • Changing out the cables
  • Power cycling
  • Factory reset
  • Checking for fault codes

Absolutely none of this helped, whatsoever. It’s beginning to get very infuriating since our drivetrain requires two motors pre side and if one motor controller is off on one side, it’ll fight the other motor in the gearbox.

If anyone has any tips, please let me know. Thanks!

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