Hello.....Thank you in advance for anyone that can help:

So my 1992 LS 400 has been having intermittent electrical issues centering around the gauge cluster. First, the analog odometer stopped working, then shortly after the Speedo started going bonkers. It would bounce from zero to 140+, just erratic and without warning. Once it started it continued even when I would pull up to a stop; that is it would continue to bounce erratically. Then either after a few miles or parking the car for a bit it would totally correct itself.

Then recently, it started effecting the Tachometer as well..........it too would go erratic at the same time the speedometer would go crazy. Sometimes they both would not work at all, or one or the other and then go back to normal like nothing had happened..........No other warning lights had presented themselves.

Now, when the speedo decides to go bonkers, the shifting of the car becomes erratic, sometimes shifting hard, or not being able to shift easily at all; even sometimes seems like it skips a gear and then downshifts hard. Then corrects itself once the speedo starts working normal again......All without any warning lights illuminated.

This has been a highly maintained vehicle and has about 140k on it........

Reading the threads I am leaning on a malfunctioning Speed Sensor, but how do I tell which one? Please feel free to email me at : Patdixon82673@hotmail.com

Thanks a ton!

 

http://www.lexls.com/tutorials/lighting/bulbout.html
^no.1 cause of electrical issues in the 1st gen LS400.

 

Thanks, but I think my symptoms really aren't similar to this.............

 

spend the 5 minutes and check the harness. ignore the symptoms listed and do it, as it's the first place to look for ANY electrical issues on your car.

the harness issue happens about 10x more than any speed sensor issue.

 

I looked at the wires and one wire (white with what appears to be a black stripe) was worn through the insulation and bare in a small spot. Otherwise all other wires appear fine.

This said, I will get it patched up..........not sure if it could be causing all the symptoms I am having. Also, a common theme I thought of as well is that the car starts acting up after it has been driven awhile. Additionally, I need to mention that this is a condo car and in Soutwest Florida

Thanks,

PTD

 

Let us know if patching that wire solves your issue. If that bare wire is contacting something and grounding out, that single wire alone could be the cause of all your symptoms. Hopefully that will be your issue.

 

We'll see. I still feel like replacing the Speed Sensor #2. From what I can find, a bad Speed Sensor would cause the Tach, Speedo and Tranny engagement to act as it did. I could only get the #2 Sensor from Autozone and will be getting it on a hoist tomorrow to replace it. This all seemed to happen at the same time so it would almost have to be related. I am not sure how to diagnose if it is Speed Sensor #1 or #2 failing at times or both.

 

Okay........Back from a lengthy morning!

For starters, the wire last night in the poorly lit garage looked like it was just skinned and it was completely rubbing on the metal that holds the hinge in place. Today, in better light and down at the garage my dad shares with other car collectors I was able to see that the wire was just about broken and only held by probably 2-3 copper strands and the rest were cut through. This said, we cut the wires, made a clean attachment and soldered them back together and wrapped the whole harness in new electrical tape. Additionally I pulled the wires a bit more and removed the plastic attachments that kept them tucked away and up in the pocket that caused the problem in the first place.......so, they hang down a little bit but I would rather have that than them getting pinched again.

With a new sensor in hand, we replaced the rear #2 sensor which from what I could tell was original. The new sensor was fractionally different with just a little bit more material at the contact end. I can say the old sensor looked like it did have a bit of wear on it, almost like one of the contacts from inside a distributor cap. Not burned or anything, but just rounded off a bit more.

Additionally, while on the hoist and doing an overall inspection, the drivers side front rubber brake line had a bulge in it like it had swallowed a grape. Thankfully Napa had one on the shelf and we were able to get that switched.

So, the moment of truth happened.........And I can say the car drives like a completely different car in all respects. Much more responsive, a "surging" problem that was there for quite sometime around the 40-45MPH range is now completely gone, an initial off the line hesitation is now gone as well, and shifts as smooth as could be. I'm amazed. No flair-ups yet with the gauges either!

Thanks for the insights!!!

PTD

 

Good news but with doing both the wire and the speed sensor at the same time you will never be sure if it was the trunk wire or the speed sensor at fault.
Had you repaired the wiring 1st then test driven the car you may have saved the cost of the speed sensor and used the money to pay for the brake hose.
But at the end of the day you got the right result, a perfectly running LS400.

 

With roughly 145k on the ticker I am okay spending $80 on a car that has been very trouble free. It is peace of mind too knowing that these do have a tendency to fail.

 

but the speed sensors are not known to have a "tendency to fail"......

i'd keep that, it's probably fine and having a spare won't hurt.