The car soulds like the battery is low but when it starts the flashers come on.
Often an alarm system will register a low battery voltage and presume the vehicle's battery is being removed to prevent the alarm from going off. They will then begin flashing and or sounding the horn.
In your case, I would presume that the battery voltage is too low which may indicate either a failed battery, or a parasitic voltage drain.
First, get the vehicle started, and run the vehicle for a good twenty or so minutes to get some charge to the battery. If you don't want to waste fuel however doing this, then I suggest using any battery charger, as all we want to do is get some voltage back in the battery. If you are using a charger though, then charge on a lower voltage setting overnight.
Once you have the battery charged, run off any surface charge by turning the vehicle lights on for a minute, then turn them off again.
You need an ammeter for this next part:
Disconnect the battery positive terminal and connect the ammeter in series with the battery and positive lead.
DO NOT ATTEMPT TO START THE VEHICLE!
With all vehicle systems off, the key out, doors closed and alarm 'OFF', bonnet close switch depressed, or bonnet/hood clasp closed (need a screwdriver), take a reading from the ammeter.
After probably no more than twenty minutes, the ammeter should be reading 0.03 amps and not much more. Anything like 0.5 or 1 amp means you have a battery drain.
If this is the case, then start by disconnecting the alarm system. If the alarm system has it's own separate speaker/horn, then disconnect this first. Many of these horns have backup batteries, which only last three or four years before they fail, which causes them to constantly draw from the vehicle battery and then flatten it when parked.
Every time you disconnect an item or system, check that ammeter again to see if the amps have returned to normal. Pull fuses one by one, checking the ammeter each time for any change until you find the system which is causing a drain, then attend to that system.
If your amps are normal however and your battery is still loosing charge when parked for any short length of time, i.e. a few days or so, then your battery is at fault and requires replacement.
Just before changing your battery, do one last check, which is with the vehicle running. You need to reconnect any battery cables, and start the vehicle. Using the voltmeter once more, check the voltage across the terminals with the engine running. This is your charging voltage and it should go up to around 14 volts if revving the engine slightly. If still around 12 volts only, then you have a charging issue, which is probably the alternator.
Nov 11, 2012 |
2008 Toyota Corolla