(In advance sorry for the long post)
Hello Guys im currently new to this forum I picked up a sweet 99 gs400 a few weeks ago for a daily/family car since I no longer want to drive my show truck to work everyday lol. I have currently ran into an issue with this car since I’ve now went back to work after taking some family leave. These two early cold mornings I get in the car to head to work I put my key in the ignition the steering wheel adjusts I turn the key my automatic headlights turn on but when I fully turn the key to turn on it does nothing. No sounds of struggling everything stays on except for the speedometer lights those turn off. Yesterday morning I removed the keys and tried again held it for like 10 seconds and turned on. This morning I had to hold it for like 30 seconds. As soon as the car turned on the check engine, vsc, and vsc off lights came on right away I drove it to work still about 15 minutes away from where I live. Parked the car. I went back to turn it on to park it where my tow truck was parked and it turned on without an issue and the 3 lights were gone. Not sure what the issue is starters typically just go bad and won’t turn on and alternator did get fixed last week but usually with alternators it’ll drain out the battery which all the electronics still work before I even turn the car on. Has anybody ever experienced this issue? And what was the fix because it only has done this too me these two mornings when it’s extremely cold out. Any help or advice is greatly appreciated!

 

Start with the basics. Check the connections at the battery to ensure they're tight and clean and then go get the battery tested.

 

If the Alternator was just bad, there is a good chance that it took the battery out as well. I would immediately clean up all my grounds, especially the ones on the alternator bracket (I do this day one of old car ownership). But don't start pricing out a starter without being 100% sure about that battery. If you are gonna own a 20+ year old car, you need to get yourself a decent scanner. There's a good chance that code is for something else entirely and you wanna know exactly what it's telling you.

 

This is something I'd suggest scanning for codes for. Seems like possibly an ignition switch or neutral safety switch issue. Something that isn't getting the signal that the key is turned to run or that the transmission is in park. See if it starts better in neutral, if so, likely the latter.

 

The symptoms you described are similar to what I experienced just before my alternator gave up the ghost. At first I thought it was a loose battery connection because the lights would come on while I was driving. When they first came on I pulled over and wiggled the battery post and the lights went out. Later I tightened the battery clamp and the problem went away for about 3 weeks.

For another couple of weeks I would stop and jiggle the battery wire and the problem would stop. Then one day the car quit dead in the middle of a busy street. Everything electrical was dead. No lights, no flashers nada!

I had AAA tow me to my mechanic and the diagnosis was a dead alternator. after 330K it owned me nothing! We put in a new alternator and that was a year ago. Everything has been working flawlessly since.