2015FA12
December, 2015
Page 1 of 2
SUBJECT:

Customer Satisfaction Field Action 2015FA12 – Recalibration for Code Setting MIL Lamp During
Shutdown on HD OBD Compliant Buses

MODELS AFFECTED:

H 40/50 EP Hybrid Systems certified to operate in California, which Allison commonly
refers to as Cert Plus models, with 2015 HD OBD Certification built between January
and November of 2015

Introduction:
Allison Transmission, Inc. has identified a customer concern with HD OBD compliant hybrid systems in transit
buses. The MIL lamp can sometimes set due to hybrid motor speed sensor diagnostic codes (73­35, 73­38, 74­35,
or 74­38) detected during shutdown. This momentary fault sets the MIL which remains on until 3 successive
drive cycles are completed without recurrence. On buses not subject to HD OBD regulations, the speed sensor
diagnostic code could set; however, without a persistent MIL lamp illumination, it is likely the operator would not be
aware the event occurred. This Customer Satisfaction Initiative installs a new SID that disables the motor speed
sensor diagnostic check during shutdown.

Customer Notification:
Allison Transmission, Inc. will be contacting the fleets affected by this field action and they will contact our local
distributor to perform the re­calibration.

Service Procedure:
1. Verify that the latest versions of Universal Allison DOC® and TCM Reflash are installed on computer to be
used.
2. Connect Universal Allison DOC® to the vehicle.
3. After connecting to the vehicle, check for possible active and inactive Diagnostic Trouble Codes.
4. Record all Customer Modifiable Constant (CMC) values.
5. Reflash the SID. Use HEVFGL0A (6C­FGL0A­021­E)
6. After recalibration is complete, connect to vehicle using Allison DOC® and verify installed SID.
7. Modify CMC values as needed to restore vehicle to original settings.

SM / FA1111EN

3039950

Copyright © 2015 Allison Transmission, Inc. All Rights Reserved.

2015FA12
December, 2015
Page 2 of 2

Claim Information:
Allison Service Outlets shall submit an AWAARE claim on each vehicle completed under the Field Action.
Approved Authorized Allison Electric Drive (H 40/50 EP) Hybrid System Overhaul facilities must submit claims for
work performed per this Field Action as follows. Claims must be submitted against the Drive Unit serial number.
Allison Service Outlets must use the published Allison Transmission Labor Time Guide for work performed. Any
parts, labor, or net items requested that are not specifically identified in this Field Action Letter must be explained in
detail for consideration.
Claim Type 4
Special Activity Code 2015FA12
Field Action Authorization Number Provided from Extranet, must be listed in claim narrative
Product Code 71
Labor Operation Code Labor Hours Labor Operation
00096501 1.0 hours Recalibrate ECU
00096400 0.5 hours Final Test Drive Vehicle

Contact Information:
If you have questions concerning this Global Customer Satisfaction initiative, please contact:
Allison Transmission, Inc.
Attn: H 40/50 EP Service Group
P.O. Box 894, Mail Code M5B
Indianapolis, IN 46222
1 (800) 252–5283

Copyright © 2015 Allison Transmission, Inc. All Rights Reserved.

December, 2015
Page 1 of 1

TO:

Customers of buses with Allison H40/50 EP Hybrid Propulsion Systems with certification to comply with
HD OBD

SUBJECT:

Customer Satisfaction Field Action 2015FA12 ­ Recalibration for Code Setting MIL Lamp During
Shutdown on HD OBD Compliant Buses

MODELS AFFECTED:

H 40/50 EP Hybrid Systems certified to operate in California, which Allison commonly
refers to as Cert Plus models, with 2015 HD OBD Certification built between January
and November of 2015

Complaint:
Allison Transmission, Inc. has identified a customer concern with HD OBD compliant hybrid systems in transit
buses. The MIL lamp can sometimes set due to a hybrid motor speed sensor diagnostic codes (73­35, 73­38,
74­35, or 74­38) detected during shutdown. This momentary fault sets the MIL which remains on until 3 successive
drive cycles are completed without recurrence. This Customer Satisfaction Initiative installs a new SID that disables
the motor speed sensor diagnostic check during shutdown
Issue: Through extensive testing it has been determined that the high voltage discharge from the DC capacitors
during vehicle shutdown allows the motor/tone wheel to vibrate. The tone wheel movement results in a motor
speed sensor signal that is judged to be a failure and the MIL/check system lamp is illuminated and a DTC will set.
This issue could occur on all H40/50 models, and it is easily noticed due to the presence of the MIL lamp.
Solution: This event is an unnecessary enabling of the fault detection occurring at power down (HV discharge).
The solution is to disable the diagnostic code during shutdown.
Our records indicate that you are the current owner of a bus requiring a recalibration. Allison personnel will be in
contact with you to schedule recalibration of your bus.
We regret any inconvenience this may cause; however, we have taken this action in the interest of your continued
satisfaction with Allison products. Allison is committed to your satisfaction and wants you to have absolute
confidence in your Allison product.
Should you have a question concerning this matter, please contact us at 1­800­252­5283.
Thank you for your confidence in choosing an Allison transmission. Your satisfaction is our number one priority.
Sincerely,
Allison Transmission, Inc.

SM / FA1111EN
Copyright © 2015 Allison Transmission, Inc. All Rights Reserved.