Odd issue with 08 Toyota Yaris

[speede5]

Check the battery connection. The clamp could be tight and powering the starter, but there could be another cable or two on the clamp, or a terminal block nearby, that are loose. Does it have the booster terminal block? check there.

If it starts ok on the days the clock is flashing I would steer towards a bad connection.

Most shops can do a battery test as well, before you replace it on spec.

[GoinAllTheWay]

Just took a quick look at it the other night. The main posts are clean and secure but you are right Speede5, a couple other smaller wires connected to one of the main leads. I'm out to buy a new battery tonight and will tighten down all the other wires at the same time. Pretty sure that will be the end of it.

[Fuzz]

Make sure you clean the terminals before hooking it up. If their is corrosion, a solution of baking soda/water will fizz until it is clean. After take some emery cloth and clean the inside of the terminal as well. If it doesn't look corroded at all, just emery cloth will do.

[GoinAllTheWay]

For sure. I even go so far as applying that conductive grease to the posts too. Supposed to prevent that type of buildup.