Once a great installation is complete you want to make sure the customer, another installer, mechanic or driver does not alter your work. Any failure of the device installed starts with a phone call to you. If you are unable to determine the reason for an installation related failure you are unlikely to get paid for the service call. The simple application of a product called Torque Seal (click here to buy online) goes a long way for discouraging the alteration of your work.

Torque seal (TS) provides visual confirmation of the connection being altered. It also provides a deterrent by indicating to the would be perpetrator that there are measures in place to clearly identify an alternation to the device or connections. When applying TS, think like someone that does not want the device in the vehicle. Think like a company driver that does not want to be tracked by his employer. How or what would he/she do to alter the GPS tracking system to render the system inoperable. Once you take this perspective you will be very thorough in the application of the torque seal.
Torque seal comes in a small tube in a variety of colors as a paste about the consistency of toothpaste. Once applied it sticks to the surface and dries hard over 24 hours. Once hard it will crack on removal making the tampering obvious. One special note to implement when using torque seal is to only apply it after the device is in the final resting place. Torque seal is designed not to come off so if you touch it or bump it on the vehicle or your hands you will likely make a mess the customer will not appreciate.

When applying torque seal apply a liberal amount to every connection. This would include: antenna to devices, wiring harness to device, cap on fuse holder, butt connectors, zip ties holding poke and wrap connections and auxiliary or PTO connection points. You can also increase the deterrence by applying TS to screw heads that must be removed to get to the device when installed in the dash of the vehicle. Do not skimp on the amount of TS being used. TS starts as a paste but dries and shrinks. If you do not use enough, it will crack when it shrinks and you may get a false impression because it cracks spanning a gap.
As with all security, you have to think in layers. Any one security breach might be explained away by a driver or customer but when there are 2, 3 or even 4 layers of protection, you can state with great confidence that someone has altered the installation. Layers of security and tampering detection may included:
Consider the cost of making a return trip at no charge to the time, effort and cost of implementing the above techniques. There is obviously an obvious value in using torque seal and other security measures. Business customers don't want you coming back any more than you want to go back. Implement these techniques, sell your value added services and generate more business.