Technical Service Bulletin
91 Microphone testing tips
91 14 35 2026895/4 April 8, 2014. Supersedes Technical Service Bulletin Group 91 number 14-19 dated January
3, 2014 for reasons listed below.
Model(s)

Year

VIN Range

Vehicle-Specific Equipment

All

2006 - 2013

All

Not Applicable

A4, A5,
A6, A7, Q5,
Q7, TT

2014

All

Not Applicable

Condition
REVISION HISTORY
Revision

Date

Purpose

4

-

Revised header data (Added models)
Revised Service (Revised entire section)

3

01/3/2014

Revised Service (Added diagnosis step for 2012+ C7/D4; updated formatting)

2

10/5/2011

Revised Additional Information (Updated TSB numbers)

1

7/15/2011

Original publication

• Customer complains that during Bluetooth calls, the person at the other end has trouble hearing the speaker in
the vehicle.
• Voice recognition accuracy is poor.

Technical Background
This TSB provides guidelines for testing microphones in a vehicle.

Production Solution
Not applicable.

© 2014 Audi of America, Inc.

Page 1 of 3

All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of
Audi of America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval
system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior
expressed written permission of the publisher.

Technical Service Bulletin
Service
Verify vehicle hardware and software
• Check software levels to ensure that the latest software is installed. Use GFF to determine if a fault for
microphone operation is stored in one of the following address words (depending on vehicle and equipment
levels): 56, 5F, 67, or 77.
• If a fault is stored, proceed with the test plan outlined in the scan tool.
• If no fault is stored, proceed with this bulletin.
Verify the customer complaint
• Pair a known good, compatible Bluetooth phone to the system. Use it to place a call to a landline phone. The
test call must be placed with the windows, sunroof, and/or convertible top in closed position, the climate control
off, and the vehicle stationary.
• If the call quality sounds clear to the person on the landline, the microphones are okay and should not be
replaced. Proceed to the Background noises section of this bulletin.
• If the call quality does not sound clear to the person on the landline, proceed to the Check the microphones
for electrical defects section of this bulletin.
Background noises
• A microphone that is in proper working order can pick up wind and road noises, if they are excessive. These
noises can be picked up by the microphone and transmitted through the Bluetooth system, affecting call quality.
• If the customer concern occurs only when a window is down or the sunroof or convertible top is open, there
is nothing wrong with the system. No repairs should be made.
• If the customer concern occurs at a specific speed while the windows are up and the sunroof or convertible
top closed, perform a test call from a known good phone to a landline under the driving conditions the
customer has described:
- If the customer concern cannot be verified, no repairs should be made.
- If call quality is poor during road test, check for background noises. Possible sources of background noise
include: excessive road noise caused by uneven tire wear or unfavorable road surfaces, excessive wind
noise from exterior accessories (roof bars, cargo carriers, etc.), and excessive wind noise from air entering
the cabin (seals, door adjustment, etc.). Additionally, microphones can pick up noises from above overhead
console. Remove the overhead console and check for noises that can be amplified in area above
headliner.
• If the customer is only able to duplicate the concern with his or her phone, pair a known good phone to the
vehicle and ask the customer to use it to place a test call to a landline. If the customer is unable to reproduce
the concern on the known good phone:
• Delete all Bluetooth profiles from the customer’s phone and vehicle.
• Perform a power cycle of the customer’s phone and a three-finger reset on the radio
• Pair the Bluetooth connection of the phone and hands-free system.
• If the customer still experiences the concern only with his or her phone, advise the customer to contact the
cellular phone provider for replacement hardware.

© 2014 Audi of America, Inc.

Page 2 of 3

All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of
Audi of America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval
system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior
expressed written permission of the publisher.

Technical Service Bulletin
Check the microphones for electrical defects
• Gain access to the microphone connection in the
overhead console (Figure 1). Note that the number of
microphones will vary depending on model.
With a DVOM, perform the following voltage
measurements:
a. Microphones plugged in, voltage reading at
1.1,1.2,1.3 is 4VDC +/- 10%
b. Microphones unplugged on the body side of
harness, voltage readings at 2.1,2.2,2.3 is 8VDC +/10%
• If voltage is present in steps a and b:
• Inspect the wiring and connectors for visible signs
of damage.
• If voltage is not present in steps a and b, or if incorrect
voltage is found:
• Test for proper output voltage at the module. Test
must be performed with all microphones unplugged
from module.
• If output voltage at module is ok, reinstall
microphones and perform voltage drop test on all
wiring from module to microphones.
• If all steps checks OK, contact TAC for further
assistance. Do not replace microphone without TAC
approval.

Figure 1. Microphone connection. Protective covers
have been removed to show pin locations.

Warranty
This TSB is informational only and not applicable to any Audi warranty.

Additional Information
The following Technical Service Bulletin(s) will be necessary to complete this procedure:
• TSB 2026851, 91 Belt Microphone Overview
• TSB 2026888, 91 Bluetooth Phone: poor call quality
• TSB 2027718, 91 Bluetooth Phone: call quality poor at other end
All parts and service references provided in this TSB (2026895) are subject to change and/or removal. Always
check with your Parts Department and service manuals for the latest information.

© 2014 Audi of America, Inc.

Page 3 of 3

All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other intellectual property rights of
Audi of America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of this document may be reproduced, stored in a retrieval
system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may these materials be modified or reposted to other sites, without the prior
expressed written permission of the publisher.