Ask the Mechanic: Why does my Jeep’s battery drain?

Hello Paul, my 1997 Jeep Grand Cherokee Limited 6 cyl will not start after being parked for more than four hours. Before I even put the key into the ignition, I hear a clicking noise on the right side maybe under the hood or dash. Battery test was okay, as was the alternator. Kabanda. 

Hello Kabanda, your Jeep may have a battery drain problem.

This can be caused by a number of issues, including faulty light switches, broken or loose battery terminals, dirty or corroded terminals, parasitic draw or short drives.

Faulty light switches for cabin, trunk or glove box lights can cause battery drain if left unrepaired and the lights on.

Broken, loose or corroded battery terminals will not allow a battery to fully charge. Parasitic draw can happen when faulty control modules or relay switches keep electrical consumers running, even when the car is switched off.

These can be investigated by a car electrician who will isolate different consumers as he tests battery draw. 

Occasionally, an aged battery can be affected by short drives and long parking since it is not charged enough during the short drives. Investigate these possible causes. 

Why are my car lights not working?

Although its blinker lights work perfectly, my car’s tail and brake lights are not functional. This is a recent issue. All the bulbs were checked and are in good condition. Could it possibly be a fuse problem? Derrick

Hello Derrick, have the bulb sockets checked for corrosion damage or harness (wire) connectors for broken or loose contact.

Damaged bulb sockets or loose circuits will not allow current to light the bulbs. This is common with aged lights or those that have been infiltrated by rain (bad seals) or jet spray water causing corrosion damage. 

Usually, there is one fuse for the individual light clustre and if it blows, all bulbs will not work.

Having some bulbs work means there is power supply but it is not complete due to connectivity or bad/corroded sockets.