# Service bulletin SC\-21\-077

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

- Type: Service bulletin
- NHTSA id: 11013538
- Published by NHTSA: 2025\-02\-04
- Manufacturer's number: SC\-21\-077
- Manufacturer's date: 2021\-06\-04
- Campaign id or software version: SC\-21\-077
- NHTSA component: ELECTRICAL SYSTEM; FUEL/PROPULSION SYSTEM

## NHTSA's summary

Transit bus software update to the batteries, charge controller and vehicle controller. Fixes coolant level LEDs, ESM updated specific parameters around temperatures and auto pack configuration, BMS SW resolves brick imbalance, min/max humidity levels.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2021/MC-11013538-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2021/MC-11013538-9999.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Electrical system, Fuel system

## Vehicles listed

- 2019 to 2021 PROTERRA CATALYST
- 2019 to 2021 PROTERRA ZX5

JSON: [/v1/bulletins/11013538](/v1/bulletins/11013538)

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