TT 58 18 01

Technical Tips
Technical Tip
Topic
58-18-01TT – Key Battery Diagnosis
Market area
United States 444 Volkswagen of America, Inc. (6444)
Brand
Volkswagen
Date
July 27, 2018
Condition
ATTENTION:
THIS IS A TECH TIP, NOT A TECHNICAL BULLETIN.
TECH TIPS ARE NOT ASSOCIATED WITH WARRANTY CLAIMING.
Key Battery Diagnosis
Model(s)
All
(except Routan)
Year
Eng. Code
Trans. Code
VIN Range From
VIN Range To
2011-2019
All
All
All
All
Technical Background
There is no specification for testing the open circuit voltage of key batteries. Remote keys are designed to function
normally with voltage less than that of a new battery.
Service
The following methods are recommended to make a correct diagnosis of the key battery:
1. Check LED Indicator on the Key
• Watch the LED indicator on the key while pressing a button.
• As long as the LED illuminates, the key will operate within the normal range.
• If the LED does not illuminate when pressing a button the battery should be replaced.
2. Check for MFI Message
• With the ignition on, push any button on the key and watch for a message in the MFI.
• The battery condition is transmitted from the key to the BCM.
• If a MFI message indicates the key battery is low, it should be replaced.
3. Measure Battery Voltage – Using 330 Ω of Load
• It is necessary to measure the voltage with a load to simulate operating conditions.
• Resistor decade box VAS 6345 may be used to dial-in 330 Ω.
• Connect the resistance of 330 Ω in parallel with a digital voltmeter.
• Measure the voltage across the coin battery after 1 second.
• If under 2.6 Volts the battery should be replaced.
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Technical Tips
4. Check DTCs and Measuring Values for Remote Key (MQB Vehicles Only)
• MQB vehicles will store a DTC in the BCM if a key detects a low battery condition.
• The DTC will indicate which remote number reported the low battery condition.
• Use measuring values to determine the current remote number and battery condition.
• AW 09 > Guided Functions > Measuring Values > “Vehicle key with remote control”
• As a button is pressed, check if the current remote number matches with the DTC.
• As a button is pressed, if the battery condition is “low” or “Not OK” it should be replaced.
5. Test Battery using a ZTS MBT-1 “Multi-Battery Tester”
• This tester is commercially available in the United States.
• The result of the pulse-test is displayed as a remaining percentage of battery charge.
• If the indication is 60% or less on the ZTS tester, the battery should be replaced.
Additional Information
Revision History
Revision Number
Released Date
Reason For Update
2051993/1
7/27/18
Original publication.
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