AutoFocus: Ford’s intermittent dead battery problem

2003 Ford Focus (Ford Motor Co. photo)

We all know that intermittent problems are the worst thing to try to diagnose, mainly because when the problem is not present, there is very little we can do to pinpoint it. We get these types of calls everyday, and usually the technician is just hoping we’ve run into something common that fits their symptoms. In a few cases we get lucky, and it is a common problem and we can point them in a good direction; but, more times than not, all we can do is try to help with the diagnosis once the vehicle decides to act up.

A shop called me recently on a 2003 Ford Focus. The customer’s complaint was the battery would be dead some mornings, but when they got it to the shop, it worked fine.

It was noted that the customer had installed an aftermarket CD changer for the stereo system, but the factory stereo was still in place. The CD changer was disconnected to eliminate it as a source of the problem. The battery was also tested and found to be on the weak side, so it was replaced to try to rule out a failing battery.

When the car came back after a week with the same complaint, the shop asked the customer to leave the car so they could try to duplicate the problem. The car was left at the shop and continued to work flawlessly for several days. One day, however, while monitoring the draw on the system, roughly 5 amps showed up for a short time and then went away. We started questioning the ammeter since it was so inconsistent. At this point, another ammeter was used to verify the test results. With the second meter in place, the same 5-amp draw was seen intermittently again. There was no rhyme or reason as to when the draw would show up; it did not matter if the vehicle was still in its roughly ‘45-minute awake mode’ or well after the 45 minutes when all of the modules in the car would be in ‘sleep’ mode.

At least now we knew there was a 5-amp draw, which would certainly pull a battery down overnight if the draw stayed present for several hours. The next challenge was narrowing down the draw. When the draw was present, the standard procedure of pulling all fuses one at a time was used. Most of us at Identifix recommend pulling each fuse and then leaving them out. Putting a fuse back in can wake up a sleeping module, causing erroneous test results. As each fuse was removed from the vehicle, the draw would still show up intermittently! At this point, about the only thing left that would cause a draw would be the alternator.

« Previous  |  1  2  |  Next »

Related Topics: Auto Service, Exhaust systems, Ford Motor Co.

Recent News

• TIA, Federated Insurance partner for training
• Free Service Tire Co. opts for Aftersoft's VAST
• Successful Moto3 test for Mahindra Racing at Valencia
• Rollier to step down as head of Michelin
• One word for Michelin's profit in 2011: Wow!
• Chopard Porsche switches to Dunlop tires
• Avon begins support of British Hillclimb Championship
• RMA: At least last year, winter tires ruled
• Passenger tire shipments fell 2.8%, says RMA
• MTD reports future concepts – 51 years ago