So, I've just bought a used 1995 ES 300. It's one-owner and only has about 103k miles on it, and has been very well taken care of. I figured it's not likely I'm gonna find another second or third generation ES in as good of condition as that anytime soon, so I went ahead and bought it. One little problem though: as I was driving home from the dealership on the highway, the engine stopped and the car died completely, no accessory power, gauge cluster tried to light up and the temp needle moved when turning the key, but otherwise it seems like the battery must have been completely dead. I've already had it towed to a nearby mechanic, but it was in the evening and they were already closed, so I'll have to call them in a little bit (it's the next morning now).
So, obviously this is not just a battery issue, otherwise the engine would not have stopped running while driving down the highway. When I first took the car for a test drive the salesman had to jump the battery, the car had been sitting at the dealer for 2 months so I didn't think that by itself was any cause for concern. I then took it for a test drive with no issues, and also came back and took it to get a third party inspection (which found only minor issues). Once I bought it, I went to the gas station, filled it up, and drove a decent distance on the highway before it died. When it died I had the headlights on, and I think the foglights as well because the foglights were in the on position at the dealership for some reason, and also the automatic climate control. No radio or anything.
Of course, the logical conclusion would be a dead alternator, but I've been doing some research and it seems a lot of people have gone through multiple alternators and batteries in these models without finding the actual problem, and I don't want to have to deal with that. First off, is it possible that the dealer just never fully charged the battery after the test drive and the underpowered alternator was not able to properly charge an almost-dead battery with the headlights and climate control on? This seems unlikely, but figured it was worth asking. What checks should I have the mechanic do? Based on what I've read I should have it tested for parasitic draw, and have all the connectors, wiring, and grounding points checked? Is there anything else? Thanks in advance, I'm really hoping this will be an easy fix.

 

Why ask us what your mechanic should do? That's up to the mechanic if they are decent at their job they will find the problem quickly. The dealer you bought the car from is negligent they sold you an unsafe car.

 

I mean, I'm hoping that the mechanic will find the problem and it's an easy fix. It would just be nice to know what things to look for in case they can't find the problem or their fix doesn't solve the issue, especially since I know there are people with this generation of ES who have had to have multiple alternators and batteries replaced without their mechanic finding any other issues or being able to explain why they are going bad so quickly.

 

Alternator and battery will need to be load tested. And no the car will not run if the battery is bad/failing it will shut off even if the alternator is good.