TCU FAQs

TCU Frequently Asked Questions

When the vehicle is powered off and not on shore power, what happens to the TCU?

• The TCUs are wired to always stay on due to the long boot-up time.  This will ensure that the TCU can capture the first few minutes when the vehicles is dispatched.
• For vehicles that may not always be connected to shore power and power drain is a concern (such as fire command vehicles and other passenger cars), the TCUs go into Standby Mode when the ignition is off.  The TCU will not be able to record any data for the first minute until ignition is on and the unit has successfully booted up.

Does the TCU still send faults and alerts when the vehicle is powered off?

• Faults and alerts are generated from the vehicle when the ignition starts and activates the entire CAN bus, which usually takes 15-30 seconds.
  
• The TCU starts transmitting data when the vehicle ignition is detected (white wire).

What is the power draw of the unit when the vehicle is turned off?

• Since the units are always on, the current draw is roughly 200 mA.
• For fire command and passenger vehicles, standby current draw is 1 mA.

When ethernet is used for connectivity and the router/model is powered down, what happens to the data collected by the TCU that was gathered with no connectivity?

• Messages are stored by the TCU until connectivity is restored, at which time they are forwarded.