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Abs Pump, Vsc, Radio, Domelight Cig Lighter All Cutting In And Out


Greg5OH
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car is a 2000 ls 400 115k miles.

just crusing down the highway, the cig lighter, domelights, radio etc all start cutting in and out, the vsc and abs light turn on.

yes battery new and good, alternator charging, all connections clean in engine bay.

I see that all these components share same ground, IG and IF, which is behind the radio, and behind the glovebox.

i checked the ground behind the radio and thats fine, but i have not gotten to behind the glovebox. Which is also where the vsc and abs ecus are.

Also, the abs module underthe hood beside the headlight is whirring with key off. as soon as u turn ignition on it stops, then the relays click, and then the abs motor/pump turnins on and off randomly untill you unhook the battery.

what the heck is goiung on, what kind of tests can i perform? It sounds like a grounding issue, and maybe it is with the one behind glovebox...but i somehow doubt it..

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Mysterious electrical issues, huh? Sure does sound like an intermittent connection yet you have done a fairly thorough job of checking battery and grounds.

Have you tried hooking up an OBDII scanner to see if there are any codes? But more importantly, try to determine how well the ECU is communicating with the scanner. Is it rock-solid or having trouble reliably talking back and forth? I am really wondering if the capacitors in your ECU or other computer systems are going bad. It could still be a bad connection somewhere but give it some thought.

Here is a link that might be of interest. It does not mimic your cars strange behavior exactly so maybe it is not the issue. Still, I feel it may warrant more investigation until ruled out. -> http://www.clublexus.com/forums/ls400/656360-all-my-crazy-lexus-issues-solved-ecu-leaking-capacitor.html

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my two immediate thoughts were-bad ground, and leaking caps.

however i doubt its leaking caps (if they are i believe it would be a different issue as the abs and vsc is controlled by their own ecu).

DO you have any tips on removing the glovebox? Thats where one of the grounds and the computer is.

these pics from my facotry wiring manual (first thingi bought wheni bought the car few motnhs ago! good buy!)

70D250F4-A492-40A0-A3B3-E70D49E1B6AC_zps

thje second pics here, shows garage opener, vanity lights, wireless entry, vsc ecu all ground to the same ground "IG", which the manual shows to be behind the radio. However, to my dissapointment..that groudn was fine. :( it was a crap picture but a secondary ground is "IF" behind the glovebox.

6E0D009F-08FD-47A5-AE7C-76D7BED02142_zps

if the grounds are good, im wondering if perhaps the ABS module took a crap and is grounding out internally. But that also doesnt make sense because the fuses are all good.

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Again, I will say that I would recommend hooking up an OBDII scan tool to see how the ECU behaves and if there are any codes. It might be trying to 'talk' to you.

Have you tried clipping a jumper wire onto the neg. terminal of the battery and connecting that directly to the chassis? That would ensure a good connection directly from the source to the rest of the system (if only temporarily) and might give some clues.

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no codes as predicted.

guys im at a total loss. all fuses fine, all grounds fine, all connections fine. I seriously dont understand. I do not understand why the abs motor turns on bytiself with key off. and i dont get why i cant get power to keyless, cug lighter, radio, vanity lights..

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no codes as predicted.

guys im at a total loss. all fuses fine, all grounds fine, all connections fine. I seriously dont understand. I do not understand why the abs motor turns on bytiself with key off. and i dont get why i cant get power to keyless, cug lighter, radio, vanity lights..

Greg, you have to be very careful how you approach these kinds of problems. I can tell from your comment "no codes as predicted" that you have your mind made up on certain approaches. And that is a 'dangerous' mindset to have when trying to troubleshoot to the root cause level. I do not know how many guys I have known throughout the years who have said "I tried EVERYTHING but I am still stumped". Well, in fact, they did not try everything and the things tried were done with preconceived notions as to what was wrong. The root cause almost always turned out to be something they had 'tried' but dismissed because they were sure that was not the problem.

Usually, issues are something simple, though not always. But most times they are. So, if you are ready to have at it again, we can probably mention some areas to look at... maybe for the second time. You have the service manual which is nice. I would suggest that you look at a simple circuit such as the cig. lighter and determine why that is intermittent. You may have to instrument some points along the chain to the battery but it is do-able. I have experienced fuses that look good and even work most of the time but the connection inside is intermittent. A real puzzler until you realize what it going on. So, I encourage you to keep an open mind and approach every connection, fuse, circuit with a suspicious eye until proven, without a doubt to be working properly.

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thanks landar. Yes i get very frustrated easily with electrical. Today i checked the continuity at the ignition switch as outlined by the wiring manual. Didnt get to anything else. Abs pump still freaks out by itself. goes away when relay is pulled.

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checked and tested the ignition switch, all was fien there. the hunt continues.

Im leaning towards it beign a bad VSC and ABS ecu.

and i see the circuits with keyless, garage door opener, radio, dome lights are all tied together, adn share grounds with the ecu and who knows where else they go...but could a bad ecu also take out that whole circuit?

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Since your ABS is activating even with the key off, 'something' thinks the wheels are not in sync. In other words, the ABS controller (wherever that is) is either not working correctly or has a sensor malfunction. With the key off, the controller should not even try to activate the ABS module, yet it is. I think I would locate that module and pull the connector just to see what happens. Of course the ABS will be disabled but you might try to start it and see how it behaves. Maybe the main engine ECU will not see the ABS module and refuse to start. I really don't know but it could yield some clues.

You have to experiment a bit to gather clues which will eventually point to the root cause.

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tonight im going to check the brake fluid level switch as it is directly tied to the abs motor. Also will check the voltage from fusbile link to pin 1 on the ABS motor relay. I suspect it will simply give me fluttering voltage and will basicaly tell me nothing that i dont already know, that something is triggering the abs motor, and all keyless, garage opener, dome lights etc dont work.

Im also going to find out exactly where my aftermarket air ride controller is getting its power from. I was assuming 12v cig lightrer since it took its place, but the bundle of wires runs somewhere back along trans tunnel and dissapears under the carpet. Cant see it from under the little center console tray when I remove it.

Also need to locate J9 connection. But i dont think thats the issue either, ebcase looking from the post i provided the pic, vanity lights, moon roof have nothing to do with connector J9. and ground IG is solid and fine.

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wait...you have an aftermarket air ride controller? hmmm. Someone was into the wiring, huh?

If you pick one outlet, say the cig. lighter, and track down why that one item does not work, you may get to the source of the problem. I was thinking maybe you could plug a 12v light into the cig. outlet and then start moving various wiring/connectors/grounds/fuses to see if the light might flicker.

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yes aftermarket air ride and radio. Thsi is moe than just a loose wire i think. Well-the radio-light circuit could be a loose wire, but that does not explain the abs motor spazzing out. WHen it spazzes is does not affect the dome light or that whole circuit in anyway. They jsut remain off.

im keeping the dome lights turned "on" so if something flickers i will know instantly.

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could be, and also my greatest fear. But that whole domelight, radio, keyless are all on one circuit, and keyless has its own computer, and thats out as well. Dont think the ABS computer would make the keyless computer turn on/off though?

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i found a few interesting things today.
1) in the driver fender, in that big harness, two wires were corroded and disconnected. a very thin red one and a purple one. obviously need to reconnect those to look further.
2) There is a grey wire that was ripped from somewhere up in the dash. Schematics are showing it to go to body ecu and linked with radio number 2 fuse. So need to find wher eexactly it came out of and put it back.

The abs motor randomly fixed itself, but then i undid battery, put it back then it started doing its thing again. But now its fine again...

busy this weekend but hopefully get those wires reconnected on sunday night. Looks like im goign to have to move that whole harness out of the way, the original room was rubber thru and the PO had put a little plastic shield around it.

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bad pic but you get the idea

C5447D53-72C4-4DCE-9847-56CDEB95F0E7_zps

i checked the voltage, both the red and purple have 12 volts from wire running towards front of the car, or fuse box/distribution block. nothing on the other side. going to do a quick fix on those and see if i can tuck the harness awya a little more on sunday night, till I have time to make an extended harness and route it the way I want it.

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I saw in your similar thread on ClubLexus that you had removed the inner fender liners when you lowered your car. Yours is not the first case where wacky problems have occurred when a wiring harness in the fenders gets friendly with a tire. That has happened even when the fender lines have not been removed and a tire on a lowered car wore through a fender liner and chafed a wiring harness..

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what the heck? That looks like the whole wiring harness got yanked on or chewed. Not good. Did squirrels get in that thing?

"you had removed the inner fender liners when you lowered your car"

I try to address these issues thinking(hoping) that the car is pretty much virgin only to find out there is more going on (modifications) and I only have a partial picture...<sigh>

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lol sorry landar, thansk for all the input so far guys! im not going to sit back till i hook those wires back up...kind of doubting my issues are caused by this, but hey they gotta be fixed anyway.

the car rides LOW. exhaust was tucked up a few inches to prevent rubbing, roll center adjusters, etc. its on air, but i like to ride as low as possible

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So, essentially, you 'done' it to yourself. I do not share your level of enthusiasm for slamming an LS but to each their own.

Let me ask you a question: What prevents this wiring issue from happening all over again?

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