Troubleshooting the Tire Inflation System (TIS)

Learn how to troubleshoot issues with your Tire Inflation System (TIS) to ensure proper tire pressure and optimal vehicle performance.

Updated at November 18th, 2025

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Table of Contents

How to test the TIS

A quick method to test is pull the TIS lamp and connect the leads from trailer.
If the FleetPulse mobile app is reporting correct data then the lamp resistance is too high.
Check circuit for breaks, corrosion, or modifications.

All tests should have 13V applied to the trailer nose box aux. pin and 120psi applied to the glad hands.

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Issue	Part/Wiring	Test and Diagnose
The ground eyelet inside the nose box, where the TIS lamp is connected, can be broken. It's the top right stud, marked with a white terminal, in the nose box. Verify that it is securely in place and the white wire is properly connected.		Verify that it is securely in place and the white wire is properly connected.
The TIS y-harness connected between the TIS valve, TIS sensor, and iABS can be broken.	TIS y-harness for TIS valve, TIS lamp, iABS	Inspect all three connections Open them and check pins.
The iABS connector for TIS is broken.	TIS cable to iABS	Check that it is fully seated. Disconnect, and check pins.
The TIS lamp circuit from lamp to TIS valve is broken.	TIS lamp circuit	Check connections at the lamp and wiring to the TIS valve Disconnect the lamp, check the pins.
There could be too much resistance, and the TIS valve is instructing the iABS open circuit, which defaults to inflating status. i.e., The FleetPulsePTO gateway in turn reads and interprets the iABS data as such.	Connect TIS lamp trailer leads	Test the resistance of the lamp circuit if higher than 1k ohm