Something is draining my power and I looking to see where else I need to check. Trying to rule out whatever it could be. Went to turn on my car the other day and it made a single click and would not turnover. Jumped it with the portable charger and it started. Drove it for 20mins with no issues but once I parked and turned the car off, it would not start again. Jumped it again and went to Autoparts store to buy a new battery. Swapped it out and still would not start. Jumped the new battery and it started. Like wtf? Got it home, checked all the fuses and I cleaned all the grounding wires. Alternator was changed 2 years ago. Starter is old, over 100K on it, ordered a new denso one to swap it out but still trying to figure out where the power is draining. Bought and replaced the starter relay. Once I jump it, it runs like normal, no codes, no sense of losing power. I can drive it for 45mins but as soon as I turn it off, it dies. Unhook negative terminal and put it back on but there is no static spark. Could the alternator be going out already but that shouldn't cause it not to start right?

Was reading that a faulty fuel pressure sensor can cause no start as well but just ordered a new one from Lexus and will change it out this weekend. Just seeing what else I should be looking at?

 

Hello,

What Alternator did you get?
Have you ever checked the Battery Voltage before and/or after the Drive?

The car can run for a surprisingly long time with no Alternator, with one caveat being that it won't stand a chance of Starting if it stalls after a run like that. Here is a thread on how to diagnose No Charge condition, measure the Voltages when the Car is Started, and when when it's Off, that will tell you if the Battery is charging while you are driving.

Other than that, there is a reason I asked about the Brand of the Alternator, if it's one of the Store Brand units (Duralast et.al), here is a thread on how those perform, even if the Charge is present, I would suggest checking which Alternator you have installed, Denso Rebuild is the only one I would trust at this point, here is where you can buy one.

Hope this helps and best of luck!

 

Arsenii is really good, listen to him. Really good.

Even a cheap sub $10 multimeter, you can figure all this out in your driveway, better than the tests at the auto parts store. Alternator, starter, battery, others, you can figure it out EZPZ. Get one and check back.

 

I think there is a lexus recall for the fuel pressure sensor.

But honestly, I dont thniks is the root cause.

 

The alternator was a remanufactured oem from Lexus/Toyota. The voltameter read 12.6 while the car was off. Jumped the car to start it and it read 13.3. I saw it initially drop to as low as 7.9 before it went up to 13 but maybe I just didnt have a good connection with the test lead. Turned the car off and it wouldn't start again as if there wasn't enough cranking power to the starter. Makes a single click and nothing. Jumped it again and it starts. Ordered a new reman Denso alternator just in case so once I change out the starter, fuel pressure sensor and alternator this weekend, I will let you all know if the issue was resolved.

 

Your electrical system... is an ecosystem. There are multiple parts in concert. I'd sit back and watch this video from beginning to end.


Then watch this video about how to find a parasitic drain


GL!

 

So with 12.6V on the Battery, it didn't even attempt to Crank? 12.6V is the Voltage of a pretty much Charged battery.
When you Disconnect, and then Reconnect one of the Battery Terminals, do you see a lot of Sparks on said Terminal?

Try measuring the Voltage on the Battery while you attempt to Crank the car with No Booster Attached, the idea is to see how low the Voltage dips when the Starter is attempting to Turn the Engine Over. While at it, listen very closely to any Sounds from the Starter, if there is not enough Power to turn the Engine, it won't make any sounds, but if something is preventing it from Spinning, it may start making a Whining Sound, and it will Heat Up considerably. Starter in those cars seems to be easy enough to reach, try Carefully touching it after attempting to Spin the Engine, with or without the Booster, see how Hot it will get.

Was the Booster still attached when you checked the Voltage?

How well does the Engine Spin when a Booster is Connected, is it spinning like in this thread, or in this Video? The issue in that thread turned out being a Seized A/C Compressor, which created a huge amount of Drag, sometimes it may cause the engine to not spin at all. The guaranteed way to check it would be to take the Serpentine Belt off completely, but you can also Run the Engine for a Minute or so, then shut it Off and feel the Temperature of the Pulleys, if one of them is causing the Drag, it will heat up a Lot very Quickly.

Were any High Power Demand items turned On when you were checking Voltage, like Seat Heaters, Headlights, etc.? 13.3V is not a whole lot, should be at least 14V. Try Revving it up a bit, hold it at about 1,500 RPM and check the Voltage again, just in case.

That's one way to go about it..

If I remember correctly, the Fuel Pressure Sensor would Short Out the ECU, preventing the Car from Starting, but not from Cranking. Either way, even if it was to be a problem in your case, the Car won't Start even with a Booster attached, as the ECU would still be Shorted. It is a very expensive part that is hidden deep within the Engine, I would suggest avoiding its replacement for as long as possible, unless it was never replaced as part of the Recall, which may still be active.

Correction - the Sensor does prevent the Engine from Cranking, but the point still stands.


Well, I appreciate the confidence..

Hope this helps and best of luck!