TECHNICAL SERVICE BULLETIN, VIN:
WSB-07 Open Trail Secondary Alternator Replacement

January 12, 2026
Dear Tiffin Motorhome Owner,
It has come to our attention that on certain 2026 Open Trail Motorhomes, the engine may begin to charge the
batteries before the engine reaches 1200 rpms, which does not meet Mercedes Benz requirements. To meet the
Mercedes Benz requirement that no power transfers from the engine while the engine is running below 1200 rpm,
a new secondary alternator with updated firmware will need to be installed.
Tiffin Motorhomes will replace the current secondary alternator with a new secondary alternator enabled with
updated firmware.
Please take your motorhome to a service center of your choice to have the correction completed. This repair
should take 2 hours or less and will be completed at no charge to you.
A list of Tiffin Motorhomes authorized dealers is available online at https://tiffinmotorhomes.com/service-centerlocations. If you are using a service center that is not a Tiffin Motorhomes authorized repair facility, please make
sure that they contact Tiffin Motorhomes at 256-356-0261 or service@tiffinmotorhomes.com for the required
instructions and time allowed for the repair. Tiffin Motorhomes will not pay over the allowed time unless the
repair facility receives prior authorization. For authorization, contact Tiffin Motorhomes at 256-356-0261 or
service@tiffinmotorhomes.com.
This technical service bulletin will expire March 1, 2027. Please make sure that the repair Is completed prior to this
date. Work completed after this date will be done at the customer’s expense.
You may be liable for any progressive damage that results from your failure to complete this technical service
bulletin within a reasonable time after receiving notification.
We regret any inconvenience this action may cause but feel certain you understand our interest in your continued
use and enjoyment of your coach.
Tiffin Motorhomes

Technical Service Bulletin WSB-07 Repair Instructions
Purpose: Replace alternator with alternator with updated firmware.
Models: 2025 & 2026 Open Trail Motorhomes
FLAT RATE CODE & TIME ALLOWED To file the warranty claim for payment, please use the following flat rate code.
Inspected and repaired - 8907SB00 for 2 hours. NOTE: Part return of the removed alternator is required for the
warranty claim to be paid.
No authorization is required for work completed at the flat rate times stated on the work instructions. Use
“WSB-07” as the authorization on claim for payment.

Tools Needed:
Torque Wrench (w/ 30ft*lb setting)
Rachet
T45 Torx
T55 Torx
15mm Socket
Wire Cutters/Side cutters
Flathead Screwdriver

Parts Needed:
5169450 - alternator
Electrical Tape
Butt connectors

Work instructions:
1. Disconnect the chassis battery at the battery disconnect. Remove the access panel next to the accelerator
pedal (see Figure 1A). Push in the red tab shown in Figure 1B and then pull to disconnect (some models
may have a black tab). NOTE: This step is critical to prevent any unintentional short circuits or electrical
damage while working on electronic components.

Figure 1A

Figure 1B

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WSB-07 12.10.2025

2. Remove existing secondary alternator from mount. Remove positive cable and wrap cable end with
electrical tape to prevent any contact. Remove negative cable and then use wire cutters to remove blue
wire. Remove ground cable. See Figure 2 for secondary alternator diagram.
3. Install new secondary alternator (5169450). Connect positive cable and torque to 18 ft-lbs. Connect
negative cable and torque to 18 ft-lbs. Use a butt connector to connect blue wire. Locate yellow stator
wire located in the harness and use butt connector to connect to yellow stator wire on alternator. Connect
ground cable and torque to 30 ft-lbs. See Figure 2 for new secondary alternator diagram.

Figure 2
4. Complete WSB-08 to update the Lithionics battery controller settings.

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