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When one turns the key on a car, and it simply goes click, click, click, a trained mechanic doesn't proclaim a failed battery or a failed starter motor. Rather, a trained mechanic pops the hood, and first checks if the battery terminals are clean and the connections are tight – easily solutions to a seemingly catastrophic issue, quickly resolved.

A large majority of power wheelchair issues that seem catastrophic are likewise often linked to a loose plug or loose connection. Whenever a power wheelchair seems possessed, shutting down when hitting bumps – or, even more obvious, where and error code states a disconnected or missing component – it's virtually always simply a loose connection, not an assumed catastrophic issue.

Connector Construction
Power wheelchair connectors have come a long way toward durability and reliability over the past decade. The male ends commonly feature from 2 to 6 wires, which feature special metal ends, called “pins,” that literally lock into the plastic plug housing (a special tool is required to remove the pins from the plug if ever needed). The inserted wires are then typically heat-shrinked to the plug body for extra security, making a strong “harness.” The plug body then features a positive-locking clip that prevents it from coming unplugged under most conditions, and the recessed male and female plug components create a very water-resistant connection.

Connector Locations
There are actually fewer – and far less mysterious – connections on a rehab power wheelchair than most realize:

Right Motor Connector (plugs into controller)
Left Motor Connector (plugs into controller)
Battery Harness (plugs into controller)
Hand Control (plugs into controller)
Circuit Breaker
Battery Quick-Disconnects
Battery Terminals

On rehab seating, there is, of course, additional connections running to the seating module.

If one is familiar with the locations of the controller, battery compartment, and seating (module), it's often not difficult to inspect the connections. Further, if one suspects a particular cable or harness is loose, simply following the “wiring” to its origin will lead to its plug, where one can see if it's loose.

Proper Routing
The number one cause of connector issues is improper routing. Manufacturers nowadays design routing channels and clips into power bases, specifically to avoid tugging and chafing on harnessing connectors, preventing fatigue or dislodging. However, through improper maintenance or over time, ideal routing can become compromised, where plugs are pulled and wires are chafed.

Hidden Connector Issues
Even when a plug appears tight, it may not have the proper connection. Although pins lock into place, like any man-made technology, they can have issues, dislodging, not making contact. For this reason, if one suspects a bad connection, don't merely ensure that the plug is secure, but look in the male end, confirming that all of the pins are of the same depth, alignment, and color (void of corrosion).

Similarly, the circuit breaker is arguable the most overlooked – or, under-looked, as the case may be – connection on a power wheelchair. Power to the power wheelchair usually runs through the circuit breaker, so if the connections are even slightly loose, it can cause a low-voltage error, fluctuating battery gauge, or complete shutdown.

Real-World Reliability
So, the question becomes, why don't manufacturers simply make fail-safe connectors. The answer is, because they don't exist. A recent Space Shuttle launch was scrapped because of a failed single "connector," a fuse. The fact is, modern power wheelchairs endure a lot of bumping and jarring, as well as the potential for improperly-routed harnessing during maintenance – and all of this can lead to connection issues.

However, here's the good news: The solution to many power wheelchair issues comes down to a simple answer – check the connections.

Published 6/2011, Copyright 2011, WheelchairJunkie.com