# Service bulletin SM1903

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: 10163352
- Published by NHTSA: 2019\-07\-29
- Manufacturer's number: SM1903
- Manufacturer's date: 2019\-07\-26
- NHTSA component: ENGINE AND ENGINE COOLING; ELECTRICAL SYSTEM

## NHTSA's summary

Service Memorandum \(SM1903\) includes basic troubleshooting steps for Cummins engines with "Aftertreatment Abnormal Update Rate Fault Codes". These codes indicate either a problem with the aftertreatment battery power/ground circuits, the proprietary data link circuits, or one of the components connected to the proprietary data link. Both Cummins and Blue Bird harnesses include the proprietary data link circuits, and power/ground circuits. Blue Bird harnesses include the aftertreatment powerground circuits, and the proprietary data link circuits on the OEM side of the 14\-pin crossover connector that plugs to the Cummins engine harness. The Blue Bird supplied circuits go from the 14 pin OEM crossover connector to the SCR sensor table, DPF sensor table, and the DEF tank sensor. Proprietary data link circuits DO NOT go the the diagnostic port connector located inside the cab of the bus.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2019/MC-10163352-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2019/MC-10163352-9999.pdf)

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

## Components

Electrical system, Engine

## Vehicles listed

- 2017 to 2019 BLUE BIRD ALL AMERICAN
- 2020 BLUE BIRD ALL AMERICAN SCHOOL BUS
- 2017 to 2019 BLUE BIRD VISION
- 2020 BLUE BIRD VISION SCHOOL BUS
- 2020 BLUE BIRD VISION TRANSIT BUS

JSON: [/v1/bulletins/10163352](/v1/bulletins/10163352)

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