I have a 2007 IS220d. The car has an intermittent electrical fault which results in the car battery being run-down/not charged during use.
On the first occasion it failed, I had next to no warning.The car was working well, then an array of warning lights came up, power steering stopped working so i parked up and switched off. The car wouldn't restart - the battery was completely dead. I was recovered home, put the battery on charge for 36 hours, then re-fitted it in the car. Car started, no warning lights. I had been using the seat coolers (and leaving them on when the car was off), so I assumed they had played a part in running the battery down.
I carried on using the car for a couple of weeks, without any obvious problem. Then one night, I had just dropped a friend off and I pulled away from their house the battery warning light came on and power steering stopped working. I turned all electricals off, less headlights, and managed to drive home. I recharged the battery (the battery warning light went off) and the next day, took the car to the garage. They ran diagnostics, confirmed that the battery had a good charge and was in good condition. When the car was running, the battery was, at that time, being charged. there was no obvious reason for the battery not being charged. We talked about whether there might be a wiring problem and the electrical lead from the alternator up to a point near the path of the serpentine belt at the top-ish part of the of engine was checked, but all was fine. I continued to use the car (for short, run-around journeys)
A couple of days later I took a Journey into town, parked and shopped for a while, then moved to another part of town and parked up. When i returned to the car there was not enough power in the car to start the engine. There had been no battery warning light. I removed the battery, got it home, recharged it and returned it to the car, which I then started and drove home. As you might imagine, I'm reluctant to use the car!
Does any one have any ideas? Thanks. Lee

 

Have you had the alternator tested?

 

Hi Bichon, yes, the alternator was tested when I took the car to the garage and, at that time, it appeared to be working (the diagnostics showed that the battery was getting charged when the engine was running). I realise that the alternator is the most likely fault, but I'm perplexed why the battery light didn't come on prior to the 3rd failure. The light comes on prior to starting the engine, then goes out, as you would expect if there was no alternator(/battery?)-related fault.

 

What was the actual output of the alternator? My guess is it showed voltage but not amperage and you aren't putting out enough amps to maintain the battery, but it's putting out the voltage which prevents the warning lights. Once the systems has drained enough from the battery it will then throw codes and disengage the power steering motor.

 

Thanks letric74. That's very interesting and I'm not sure I was told what the amperage output was (voltage output was 13.9 - 14-ish volts, if memory serves me). I'll have it checked again.

 

Just to close this off, I had the battery and alternator checked again. This time, the voltage from the battery (without the car running) was about 12.6 v. When I started the car the volts across the battery dropped to 11.6v-ish, and continued to drop.I took this to reflect a faulty alternator. I replaced the alternator and all is now well. The battery is showing 14.2 v-ish with the car running, whether the electrical demand is low or high. A cursory look at the old alternator (which was a refurbished unit with a 12 month guarentee, fitted June 17 ) showed quite a lot of carbon deposits around the front of the unit. I'm tempted to keep the unit and perhaps change the brushes .... and perhaps the voltage regulator(?).

 

Check the brushes on the old unit, common failure point in Toyota alternators and fairly easy and cheap to replace. Typically that is the only wear I've seen in alternators from Toyota, the voltage regulator is fairly stout and rarely fails.

 

Appreciate the advice lectric74, I've keep the old unit and will change the brushes, as you suggest.