1991 Mercury Grand Marquis Battery Cable Replacement Cost

The positive battery cable transmits power to the vehicle's computer, and starting and charging system, while the negative battery cable is connected to the chassis to provide a universal electrical ground for the entire vehicle. This creates a closed-loop system where power can continuously flow through the battery, and power all vehicle functions.

The battery is considered “dead” when there is insufficient charge to start the engine, or run electrical components. When battery cables fail, this condition will occur. Normally, the first sign is dim lighting in the interior of the vehicle, and when attempting to start, the engine may crank extremely slowly, or not at all. A very rapid clicking noise is normally heard if there is any charge left in the battery, but in many cases, the vehicle will be completely unresponsive to any input. If the battery cables fail to transmit power while driving, the battery warning light will illuminate, and the engine may stall from lack of electrical power needed to run. Note, the battery may have plenty of charge, but the same symptoms are possible as that charge has no route out of the battery. In many vehicles manufactured from 1996 until present, the check engine light may illuminate, alerting the driver that an on-board diagnostics trouble code has been stored.

Vehicles with manual transmissions can be manually started by pushing the vehicle to considerable speed, and releasing the clutch quickly if the battery is dead. This method is commonly called push-starting, and is an effective method of manually starting the engine using the vehicle's transmission to turn the flywheel. This will allow the vehicle to create electrical power using the alternator, but if the battery cables are faulty, the electrical power from the alternator may never reach the vehicle's computer, and will prevent the engine from running. The vehicle may be able to start using jumper-cables, but if the battery cables are completely faulty, there may be no change in symptoms. Lastly, if the battery cables show corrosion at the battery terminal, the symptoms may return as soon as the jumper-cables are disconnected from the battery terminals.