No start problem with little (but some) power

[Jcom7777777]

No start problem with little (but some) power - 93' SC400

Hello all. I am new to this group and this is my first post. I am happy to be a part of this group and I support all you Lexus owners out there! This looks to be a very informative fourm so I thought I would post my problem as well as try to help anyone out with any problems they might have.

Well here goes...I recently bought my SC400 and it ran great at first. I started to notice dimming gauges and headlights, so I replaced the alternator and battery. Everything worked well for a while until the same symptoms started to occur...

I did find that I had a loose battery terminal connection so I tightened that up. In the midst of troubleshooting that loose terminal, I found that the ALT fuse under the hood was melted. Very interesting because the fuse did not blow, but it melted the plastic all around the fuse. I couldnt pull out the fuse, so I left it. Need say, the car still runs fine becuase the fuse is not broken, just melted around it...

Now my car is sitting in the driveway and will not start. When parked, the battery light was on and the lights and guages had been dimming. I was able to start the car up, then I shut it off, and it would not start again.

I had the battery charged at Autozone and tried to start the car. When the key is inserted I can hear some clicking coming from down by my feet. No dash lights will come on. The radio, fans, windows, mirrors, steering, sunroof, etc. will not work. The car also will not come out of park. BUT the horn, hazard, and interior lights WILL work.

I am able to pull the starter relay and hot wire the car while the key is in the ON position, and the car will start. Still though, when running all of those listed items still do not work and I cannot move the car out of park.

(I also just pulled the battery and alternator and had them tested at Autozone and they both passed)

Well thats the problem that has been haunting me ever since I purchased the vehicle.

Any advice about a possible solution would be greatly appreciated.

 

[stevechumo]

It seem as if you have a short somewhere. It's not easy to trace it, but you can start from the battery cables to the starter. Then check for the wires of the igniters & the alternator. There're also other components related to the starter as well. Here's the link to those components. You can trace the diagram. http://www.lextreme.com/dx-starter.html

 

[PhoenixTech]

If I were you I would research how to do a parasitic drop test. It will direct you to which component wiring is giving you problems. Overheating the wires can cause excess resistance in them also. Which could be part of the problem.

Mouse, Phoenix Tuning

 

[Jcom7777777]

Problem Fixed

Alright, I sloved the problem. It was the ALT150 Fuse. Even though it had previously ran with the melted plastic around the fuse, that was the culprit.

I put my tester on the fuse and it showed nothing while the fuses right next to them read 12V.

I went to the Lexus dealership looking for the 150V fuse, but they didnt have one. They said NAPA would have one, so I went there...needless to say, NAPA didnot have the fuse, not even in their book. The guy did have a 120V fuse that would fit. I bought it for about $4 and installed. To my excitment, everything worked and I took the car for a long overdue drive.

I think what happened in the first place is the loose battery terminals created a short and melted the ALT150 Fuse. There was enough of the fuse to last a while, but it eventually totally burned out (even though it appeared to be connected from the top).

Lesson: Next time your interior accessories do not work, you cannot get the car out of park, your horn and hazard lights DO work, the car IS able to be hot wired form the starter relay with the key in the ON position...check your ALT150 Fuse.

Thanks for the response's guys. I did like the hot wire from the starter relay posted on the link, that was cool.

 

[PhoenixTech]

glad you got it fixed...