JULY 16, 2025

Thieman Pickup Liftgate Installation and Mounting Guide

Installing a pickup truck liftgate like the Thieman TT15 requires precise alignment, model-specific hardware, and adherence to Thieman’s detailed instructions. This guide breaks down the full installation and mounting process using only verified manufacturer documentation. Whether you're outfitting a Ford, GM, or Dodge pickup, careful planning ensures your liftgate performs reliably for years.

• Documentation Resources from Thieman
• Overview of Vehicle Compatibility and Platform Variants
• Installation Kit Requirements by Model and Platform Width
• Step-by-Step Mounting Instructions for Pickup Beds
• Electrical Setup and Circuit Protection
• Rear Camera Relocation (Optional)
• Hydraulic Fluid Setup and Pump Access
• Final Installation Checklist and Weight Testing
• Spare Tire Access Considerations
• Compliance Notes: FMVSS 108 & 111
• Conclusion

Documentation Resources from Thieman

Information in this article is sourced exclusively from Thieman's official TT15 series documentation. Always refer to your specific liftgate’s manuals for serial number, model, and vehicle-specific procedures.

Reference PDFs Used:

• Thieman Liftgate TT-15 Owners Manual
• Thieman Liftgate TT-15 Brochure
• Thieman Liftgate TT-15 Parts List & Owners Manual
• Thieman Liftgate TT-15 Installation Manual
• Thieman Liftgate Rear Camera Kit (KIT-235)
• Thieman Liftgate Remote Control Pendant (KIT-179)
• Thieman Liftgate Cab Cutoff Switch (KIT-131)

Overview of Vehicle Compatibility and Platform Variants

The Thieman TT15 liftgate is designed for pickup trucks with bed heights ranging from 30" to 45", including models from Ford, Dodge, and Chevrolet. Platform widths range from 49" to 56", with both steel and aluminum deck options. Two-piece folding platforms are also available for select configurations, enhancing storage flexibility and usability. Installers should note that 56" platforms are tailored for pickup applications and require separate installation kits, while 49" and 53" platforms are often used on service bodies and include hardware (thieman-liftgate-brochure-TT15-LIT.pdf, pg. 2).

Installation Kit Requirements by Model and Platform Width

Installation kits must match both the platform size and the vehicle make/model to ensure a secure mount. For this Thieman liftgate, there are several installation kits, including:

• 3319-003: Ram and Ford pickups with square stake pockets
• 3319-005: Chevy/GMC pickups (CK1500: 2007–2018, CK2500/3500: 2007–2019)
• 3319-006: Chevy/GMC pickups (CK1500: 2019+, CK2500/3500: 2020+)
• 3319-001: For 49" and 53" platforms on service bodies (included with those models)

Always confirm the bed configuration and stake pocket design before selecting your kit (thieman-liftgate-installation-TT15-INST.pdf, pg. 2).

Step-by-Step Mounting Instructions for Pickup Beds

Installation begins with removing any tailgate or factory bumper that interferes with the liftgate. Key steps include:

• Prepping the Bed: Uncoil battery cables, confirm platform is fully stowed, and remove shipping feet.
• Aligning the Liftgate: Slide the threshold onto the truck bed until flush. Clamp posts perpendicular to the ground (not the bed).
• Securing Components: Bolt the threshold and post supports using hardware from the designated kit. Use spacer blocks or shims where needed.
• Bracing and Welding: Vertical and horizontal frame braces are welded (or bolted if welding is not allowed) to truck crossmembers for additional support.
• Spare Tire Access: Platform position may need to be flipped on certain Ford trucks to allow access via one of the three pre-cut access ports.
• Tightening Hardware: All previously hand-tightened bolts must be torqued down after full alignment is verified (thieman-liftgate-installation-TT15-INST.pdf, pgs. 3–13).

The TT15’s frame-integrated design and bolt-on post supports streamline this process for most full-size pickup trucks. You can find reference to this information in thieman-liftgate-installation-TT15-INST.pdf, pages. 3–13.

Electrical Setup and Circuit Protection

The TT15 system uses a 150A circuit breaker installed within 2 feet of the truck battery. Power and ground cables (supplied) must be routed securely, avoiding heat sources and sharp corners. Installers should strip the cable insulation, solder the lugs, apply heat shrink, and fasten securely. A heavy-duty alternator and a minimum 150-amp reserve capacity battery are recommended to handle the hydraulic liftgate's demand (thieman-liftgate-installation-TT15-INST.pdf, pg. 11).

This setup is critical for safe, consistent operation of a hydraulic liftgate for pickup trucks, ensuring you avoid common electrical faults or overheating.

Rear Camera Relocation (Optional)

For newer pickups that rely on tailgate-mounted rear cameras and sensors, Thieman offers camera relocation kits like KIT235. These allow you to remount OEM backup cameras and up to four sensors on TT15 liftgates with 56” wide platforms. The kit includes mounting plates that match Ford, GM, or Dodge models.

Key points:

• Only 56" platforms support sensor relocation
• OEM sensor plugs must be rotated to face centerline
• Camera position will alter the factory screen guidelines
• Installer must verify FMVSS 111 compliance after installation

Always use the rubber grommets and plastic mounts provided to secure sensors and reduce blind spots (thieman-liftgate-rear-camera-KIT235.pdf).

Hydraulic Fluid Setup and Pump Access

Proper hydraulic setup is essential for the safe and efficient operation of the TT15 pickup liftgate. Thieman specifies the exact fluid types and reservoir levels required during installation.

Acceptable fluids include Dexron VI (or III), Mobil Univis HVI-26, Mobil 1 Synthetic ATF, and AeroShell Fluid 41, among others. The fluid level should be within ½" of the top of the reservoir when the platform is fully lowered. Access to the reservoir is achieved by removing the cover plate located behind the threshold. Be sure the black plastic breather plug is installed to allow proper venting (thieman-liftgate-owners-manual-TT15-OM.pdf, pg. 10; thieman-liftgate-installation-TT15-INST.pdf, pg. 11).

Proper fluid and pump setup ensures smooth operation and protects against overheating, especially under heavy load conditions.

Final Installation Checklist and Weight Testing

Once mechanical and electrical installation steps are complete, final checks and testing are required to ensure structural integrity and performance.

Installers must fully tighten all previously hand-tightened hardware, including post supports, frame braces, and mounting plates. Thieman recommends performing a 20-cycle weight test with the liftgate loaded to its maximum rated capacity, ensuring all welded or bolted joints maintain structural integrity. The load should be centered on the platform during each cycle (thieman-liftgate-installation-TT15-INST.pdf, pg. 13).

This final step helps verify the liftgate is securely mounted and ready for long-term operation.

Spare Tire Access Considerations

Thieman designed the TT15 liftgate with access to the spare tire jack in mind, which is important for trucks still using under-bed storage.

Three pry-out plugs are located on the rear threshold behind the pump cover. For newer pickups (Chevy, Dodge, and Ford 2004+ F-150s or 2008+ F-250/F-350s), these align with standard spare tire ports. On older Ford trucks (2003 or earlier), the pump must be flipped 180° during installation to maintain access (thieman-liftgate-installation-TT15-INST.pdf, pg. 12).

This access consideration is crucial for preserving full utility of your pickup truck even after liftgate installation.

Compliance Notes: FMVSS 108 & 111

To comply with FMVSS 108, any obstructed lights removed during installation must be replaced or relocated. Thieman provides optional light kits and wiring harnesses to help meet this requirement.

For FMVSS 111, if your truck originally came with a backup camera, it must still function properly after liftgate installation. Thieman’s relocation kits assist with this, but it is ultimately the installer’s responsibility to confirm compliance (thieman-liftgate-installation-TT15-INST.pdf, pg. 13).

Maintaining compliance not only ensures road safety but also protects you from liability and failed inspections.

Conclusion

Installing this pickup truck lift gate requires following vehicle-specific procedures, using approved installation kits, and confirming final compliance with federal safety standards. From platform alignment to rear camera relocation, every step plays a part in the long-term reliability of your liftgate for pickup truck applications. Whether you’re handling one unit or a fleet, precision and adherence to Thieman’s documentation are essential for success.