SC430 - 2nd Gen (2001-2010)

SC430 electrical issues

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Old 02-22-18 | 02:10 PM
  #16  
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Thanks all for the advice. All undercovers and weather stripping is still intact and in place. Some strange things have been happening. Yesterday after I reported that at lunch most things returned to normal, I left the car until end of work day. No new rain. Went out after work to drive home and all the problems had returned! While driving home, I realized that headlights were on, but both high beam and low beam simultaneously! Then I realized that the headlight switch was nonfunctional and the HEADLIGHT ON symbol was not displaying on the cluster. Then about 25 minutes into my drive, everything returned to normal! WTH?!? I fear its only a water issue, or even the remnants of all past history with water from Shreveport. I blasted the heater to the feet for the entire remainder of the drive and this morning and while going to get lunch I have had no issues. I will say that after reading the manual, that I believe it might have something to do with Fuse 18, which lists components of the tilt/telescopic steering, headlight switch, wipers and washer system, fuel door button, etc. I'm going to replace the fuse there nonetheless once I get a 5amp replacement. As of right now, everything is working perfectly fine again. Fingers crossed. I will investigate my grommet again and maybe use black silicone rather than GorillaTape which has lasted this many years. Very strange but hopefully the end of this gremlin.

Last edited by ShawnOk; 02-22-18 at 02:16 PM.
Old 02-22-18 | 02:39 PM
  #17  
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I was thinking, if fuse 18 controls all those things, what breaks out Fuse 18 to the individual systems,

That's when I searched "SC430 Module" on ebay to see which modules came up.

This is a Total shot in the dark, but maybe you should check this thing under your dash
https://www.ebay.com/itm/2004-LEXUS-SC430-FUSE-JUNCTION-COMPUTER-MODULE-UNDER-DASH-FACTORY-OEM-413-26-A/362085545044?fits=Make%3ALexus%7CModel%3ASC430&hash=item544dfaf454:g:NqMAAOSwT6JZ1x1Q&vxp=mtr




It looks like it feeds multiple systems that are all in close proximity. That COULD be your turn signal stock, your wiper stock, the dash switches.

I am totally guessing, but so far we are stymied anyways.

Maybe water got into it, or there is a loose connection.

Last edited by DshngDaryl; 02-23-18 at 10:18 AM.
Old 02-22-18 | 03:39 PM
  #18  
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There are three junction blocks on the passenger side of the car associated with the instrument panel wiring.
Old 02-22-18 | 03:51 PM
  #19  
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With these interior grounding points.
The grounding points for the power telescopic/tilt steering wheel circuit are: IG, IH, II.



Last edited by VVTiBob; 02-22-18 at 04:05 PM.
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Old 02-22-18 | 05:07 PM
  #20  
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There are six grounding points in the engine compartment: photo shows #3 points.
  1. engine block (2)
  2. left fender (2) - directly across from the ones on the right fender under the trim cover.
  3. right fender (2) just forward of the front corner of the battery corner closest to the fender, Under the trim cover. Both fender ground points have white-black wires attached.



Last edited by VVTiBob; 02-22-18 at 05:11 PM.
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Old 02-22-18 | 08:01 PM
  #21  
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Originally Posted by ShawnOk
Thanks all for the advice. All undercovers and weather stripping is still intact and in place. Some strange things have been happening. Yesterday after I reported that at lunch most things returned to normal, I left the car until end of work day. No new rain. Went out after work to drive home and all the problems had returned! While driving home, I realized that headlights were on, but both high beam and low beam simultaneously! Then I realized that the headlight switch was nonfunctional and the HEADLIGHT ON symbol was not displaying on the cluster. Then about 25 minutes into my drive, everything returned to normal! WTH?!? I fear its only a water issue, or even the remnants of all past history with water from Shreveport. I blasted the heater to the feet for the entire remainder of the drive and this morning and while going to get lunch I have had no issues. I will say that after reading the manual, that I believe it might have something to do with Fuse 18, which lists components of the tilt/telescopic steering, headlight switch, wipers and washer system, fuel door button, etc. I'm going to replace the fuse there nonetheless once I get a 5amp replacement. As of right now, everything is working perfectly fine again. Fingers crossed. I will investigate my grommet again and maybe use black silicone rather than GorillaTape which has lasted this many years. Very strange but hopefully the end of this gremlin.
if you think it is fuse 18, then you should pull the fuse to see how your car reacts.
Old 02-24-18 | 01:46 PM
  #22  
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Shawn,
I hate to bring this up but since you recently added your emblem light, you ought to check that out too. It is possible that something you added or touched during the process may be contributing to this problem.
Old 02-24-18 | 07:58 PM
  #23  
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Originally Posted by Harold57
Shawn,
I hate to bring this up but since you recently added your emblem light, you ought to check that out too. It is possible that something you added or touched during the process may be contributing to this problem.
It has actually been disconnected during these issues as I wanted to make it more waterproof. But thank you
Old 02-26-18 | 02:49 PM
  #24  
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Originally Posted by Harold57
Shawn,
I hate to bring this up but since you recently added your emblem light, you ought to check that out too. It is possible that something you added or touched during the process may be contributing to this problem.
Way to aggregate information Harold! You are like Dr. House on that old FOX TV Show.

Shawn, how did you ground your emblem light when you installed it? Where did you get your power from?
Old 03-03-18 | 09:16 AM
  #25  
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Hi Shawn,

Question on your Electrical concern. Do you use the Keyless Entry/Remote to enter and exit your car? I ask since we believe we may have solved a similar issue with my SC. When the Tech was doing Diag on my wireless issue, the Steering wheel would not go up and my Nav door was opening on its own! My issue may be different, however Tech says that if the wireless does not work after hitting the KeyFob, and 1st Receiver in the Mirror does not send the signal to the next module and so on, the Car does not go into shutdown mode, hence, weird electrical issues!

Food for thought!

Bob
Old 03-05-18 | 11:56 AM
  #26  
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Originally Posted by DshngDaryl
Way to aggregate information Harold! You are like Dr. House on that old FOX TV Show.

Shawn, how did you ground your emblem light when you installed it? Where did you get your power from?
LED Emblem is grounded to existing chassis ground that is in the Engine Bay, driver side near windshield. Power is from the Ignition fuse in the Engine Day on Driver's side. Which also has my turn signal LED's, which are having no problems. Hoffy, even though the steering wheel doesn't move I haven't had the other problems you listed. My keyless worked perfectly fine. In any case, I changed the 7.5amp fuse and haven't had any problems since. We've had more rain and still no issues. SO i hope this was a once time thing. Fingers crossed.

Last edited by ShawnOk; 03-05-18 at 11:59 AM.
Old 03-06-18 | 11:40 AM
  #27  
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My old Volvo P1800 had a main power 50A fuse with copper conntacts on the end that would tarnish every now and then. I'd lose lights, dash and other items until I popped the fuse out, cleaned the contacts and reinserted it.
Old 03-07-18 | 03:55 PM
  #28  
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Don't mean to hijack the tread but I have some great memories of a cross country trip in the P1800 back in 1973. My best friend and I drove from the Midwest to Colorado and Utah for couple of months skiing, then across to California for a month, them down into coastal Mexico for a couple of weeks, finally back home. That P1800 ran like a scalded dog for 10k miles on that trip.
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