flipmode64

Hey everyone. Been doing a lot of searching on here and other lexus sites and google and I think I have narrowed down my problem but I am not sure.

Everything has been fine up until this morning. Turned the car on and 5 lights are now staying on the dash. Pic attached.

Car drives fine, nothing wrong with shifting like I have read that the loom in the trunk can cause. I checked the loom and from what i can see everything looks fine. I have a multimeter and and wondering how I go about testing each wire with that as I could cut a little off to expose each wire. wondering what readings i should read when I touch each wire. All fluids are fine. Battery is holding a charge at 12 volts and it is 6 months old.

I hear it is usually the black or white wire in the loom but no cracks or anything on each of the 180 degrees bends they go through. Should I cut the bends out and attach the remaining together?

Drove the car for 45 minutes and checked battery and its at full charge still but I read that this still might not rule out the alternator? Power steering res. doesnt seem to be leaking and everything in the car works fine except CC (cruise control)

I think I can narrow this down to either TRUNK WIRE HARNESS LOOM, BATTERY, ALTERNATOR ??

Do you think I should cut out all the bent parts on the loom to start? any help appreciated thanks!

RA40

iTrader: (6)

My thoughts as well especially with the trunk harness.

flipmode64

Would a bad alternator throw these kind of lights on the dash like this? they are on ALL the time from starting the car until turned off. They never flash or go dim or anything like I've read for other similar problems.

PureDrifter

iTrader: (10)

trunk harness.

fixmiester

I have no experience with the trunk harness issue, so I will defer to others about all those weird symptoms. However, you statement about the battery holding at 12 volts may be an issue. The complex interaction between marginal alternator and/or battery performance can consume a lot of time, but here are some reasonable benchmarks:
alternator output with moderate load, fast idle--13.7 to 14.5 v (measured at battery POSTS)
alternator output with heavy load, fast idle--------13.0 to 14 v
battery voltage with engine off for a few minutes, no load--12.4 to 13 v
battery voltage with engine off, headlights on for five minutes--12.3 to 12.6v
You can find pages of detailed specs elsewhere, but these are practical guidlines that I have used for decades, on every car I've owned, and they have proven very reliable. Deviations can usually be traced to dirty connections, or failing components.

flipmode64

Thanks guys. I will start off doing these trunk wires and post back when completed. thanks again

oldskewel

iTrader: (1)

It can't hurt to fix the trunk hinge wires. When I had several indicator lights (not sure if it was these, but it might have been) come on in my '91 last year, that was my first thought, and I checked them.

For me, it turned out to be the alternator. Maybe fortunately for me, the alternator died completely, causing the car to stop running after ~20 minutes (since I noticed the lights), so it was an easy diagnosis.

With the car idling you should get ~14-14.8 V (I think, roughly) across the battery terminals. If you're getting closer to 12 V, that is bad. Simple check is to check the battery terminal voltage with: 1. engine off, 2: engine idling, 3: higher RPM, like 3000. 1. should be ~12V. 3. should be ~14-15V, no higher. 2. may be a little lower than 3. (these are all from just general knowledge - the LS specs will be more precise)

mspearl95

My first thought was alternator, but i have no experience with the TW harness in these cars. I had an 87 toyota gts that would eat alternators, and every time it did, the brake and battery light would both come on. It did't have all the other indicator lights of course, so that is only a partial similarity. Definitely have the alternator tested tho.

flipmode64

Because the cruise control doesn't function I am leaning towards the trunk wiring but we will find out soon.

Will test battery. It was driven for 40 minutes yesterday and been sitting in garage for 12 hours and battery was right on 12 volts without the car on or anything.

flipmode64

OK so with the multimeter i started the car from cold, and at the battery posts it stayed right at 12v or 11.9v. turned a bunch of things on in car, A/C, all lights, fans high, cd player on. and tested at the posts and it was down to 11.3-11.5.

Sounds like alternator? or would you still think about the trunk harness?

Kansas

If the wires at the left hinge of your truck lid has not been repaired, yours might be the first gen 1 LS400 that has made it past 12-14 years without a repair. You should be able to tell if the wire cores are broken by wiggling each wire. The ones with broken cores will bend with less resistance.

mspearl95

An alternator in optimal condition should be putting out a charge of over 13.5 volts i think.

http://www.aa1car.com/library/charging_checks.htm

fixmiester

The results show you have a battery or alternator problem. From your readings, it would seem your alternator is weak--HOWEVER-- I have seen nearly identical measurements when it turned out to be a battery with a bad cell. I suggest you take it to a parts house that does in-car testing of both batteries and alternators, to see which is bad. If you can't find a place that can do both, at least get the battery checked FIRST, before you do any other repairs. Like I said earlier, chasing troubles caused by a marginal battery or alternator can eat up a lot of time, because it is harder to pin down the root cause of things that are "sort of" working, and not in hard failure.

Steve

flipmode64

havent touched anything and i took it out for a drive and halfway through the drive the ABS light is now on and the TRAC OFF light is now on.

Gear Shifter lights very dim.

Had CD player on and when i gave it gas or used brakes the audio cut out....

Can we say alternator now? Don't like driving the car with all these lights on.

Can someone respond and then I can feel safe about ordering one of the internet tonight.

Thanks again

Kansas

My recommendation is to not just throw money and parts at it. Maybe you need a professional to diagnose the problem - it's usually cheaper in the long run.