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Dragging Brakes? Traction Control? Problem Keeps Changing Wheels...


micadevcon
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Alright, I have a 91 LS400 with about 205k on it. As of late, among various other issues, I have noticed a very... shall we say, robust vibration after driving for a while. Frequency varies with speed, goes away [a little] under acceleration, continues even in neutral. This isnt a wheel-out of balance, its a WHUMP WHUMP WHUMP like the tire is flat or lopsided, the passenger seat is rocking back and forth like mad, and the brakes do shudder a little while braking like its a warped rotor... but not all the time!!! <_<

At first I thought it was a dragging caliper on the passenger rear, as the rim would suck up the heat and get very warm after the car stopped. However everything looked good, the caliper released when I had the wheel off and the car up on stands, even with car in drive, it wasnt dragging. But recently, the problem has moved! It first went over to the driver's side rear, with that wheel heating up after I parked. Then the other day it did it on the Passenger Rear and Driver Front wheels! Now, it is doing it on the Driver Front only, but severely.

My assumption is the Traction control/ABS ECU, but theirin lies another issue. My TRAC-OFF light comes on a few seconds after the car starts, and stays on. Thus, the system is disabled, and should not function. This issue [the TRAC-OFF light] has been with the car since I bought it two months ago, and went away at first when I replaced the O2 sensors. It has now returned, and now knowing how to properly read the codes, it gives me code 51. It is: "Problem in engine control system", specifically "Engine Malfunction Detection Circuit". Now, aside from throwing money at the issue and just replacing ECU's willy-nilly, are there steps I can take to find what the root of the problem is?

Any advice and help would be greatly appreciated!

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If your trac system is acting up, remove its fuse and see if the symptoms go away.

Also clear ecu memory by disconnecting battery for a while before this.

TRAC error code is cleared by tapping brake 8 times in 3 seconds with tc and e1 jumped.

Best of luck..

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Alright, I have a 91 LS400 with about 205k on it. As of late, among various other issues, I have noticed a very... shall we say, robust vibration after driving for a while. Frequency varies with speed, goes away [a little] under acceleration,

continues even in neutral.

assumption, coasting in neutral

This isnt a wheel-out of balance, its a WHUMP WHUMP WHUMP like the tire is flat or lopsided, the passenger seat is rocking back and forth like mad, and the brakes do shudder a little while braking like its a warped rotor... but not all the time!!! <_<

At first I thought it was a dragging caliper on the passenger rear, as the rim would suck up the heat and get very warm after the car stopped. However everything looked good, the caliper released when I had the wheel off and the car up on stands, even with car in drive, it wasnt dragging. But recently, the problem has moved! It first went over to the driver's side rear, with that wheel heating up after I parked. Then the other day it did it on the Passenger Rear and Driver Front wheels! Now, it is doing it on the Driver Front only, but severely.

My assumption is the Traction control/ABS ECU, but theirin lies another issue. My TRAC-OFF light comes on a few seconds after the car starts, and stays on. Thus, the system is disabled, and should not function. This issue [the TRAC-OFF light] has been with the car since I bought it two months ago, and went away at first when I replaced the O2 sensors. It has now returned, and now knowing how to properly read the codes, it gives me code 51. It is: "Problem in engine control system", specifically "Engine Malfunction Detection Circuit". Now, aside from throwing money at the issue and just replacing ECU's willy-nilly, are there steps I can take to find what the root of the problem is?

Any advice and help would be greatly appreciated!

Release the e-brake, or adjust it, or look under the car for something trapped in the e-brake actuation cables.

Or mayb even an improperly installed wheel balance weight striking the e-brake cable.

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Thanks for the quick replies!

I doubt it is related to the e-brake, but I will check clearances. It seems to release properly after being engaged.

I have cleared the ECU previously in an attempt to fix, without luck. I will take its fuse out, I had thought of just disabling it, but wasnt sure how.

wwest: Curious what you mean by "assumption, coasting in neutral". Does it not coast whilst in neutral?

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Thanks for the quick replies!

I doubt it is related to the e-brake, but I will check clearances. It seems to release properly after being engaged.

I have cleared the ECU previously in an attempt to fix, without luck. I will take its fuse out, I had thought of just disabling it, but wasnt sure how.

wwest: Curious what you mean by "assumption, coasting in neutral". Does it not coast whilst in neutral?

You said it still happened in neutral but you didn't clarify "standing still" neutral or "rolling" neutral. I assumed "rolling" neutral.

An e-brake cable binding right at the R/L "split" would/could result in the symptoms you describe.

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Alright, I think parking brake can be eliminated as a cause. The issue has now moved fully to the front driver's side wheel. It is getting very hot, and when turning or moving slowly I can see the steering wheel twitch to the left in time with the pulsating I feel.

Still looking for the TRAC fuse to disconnect it and see if that prevents anything...

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Alright, I think parking brake can be eliminated as a cause. The issue has now moved fully to the front driver's side wheel. It is getting very hot, and when turning or moving slowly I can see the steering wheel twitch to the left in time with the pulsating I feel.

Still looking for the TRAC fuse to disconnect it and see if that prevents anything...

Trac only operates (..the brakes..) at the rear.

Check and make sure your brake lights aren't always on and therefore ABS is activating even with no "braking".

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I have the exact same problem. It started about 3 wks ago. I stopped driving the car since I was too busy with the holidays etc. I have about 300km's on my LS400.

At first I thought I had a badly bent rim or the wheel nuts became lose. I did the TRAC fuse, disconnected the bat. nothing changed. Mine is only on the front. When I drive forward, the steering wheel turns to the right each time the wobble happens, if I reverse, the steering wheel goes to the left. Seems like only one of the brakes is engaging. The event happens around every 6ft, forward or reverse. Prior to looking at this forum, I thought the ABS is engaging on one wheel, due to a bad sensor or something.

I tried driving the car with the brakes engaged, still happens. Is there a way to safely disable the ABS system?

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Alright, I think parking brake can be eliminated as a cause. The issue has now moved fully to the front driver's side wheel. It is getting very hot, and when turning or moving slowly I can see the steering wheel twitch to the left in time with the pulsating I feel.

Still looking for the TRAC fuse to disconnect it and see if that prevents anything...

Trac only operates (..the brakes..) at the rear.

Check and make sure your brake lights aren't always on and therefore ABS is activating even with no "braking".

I checked the brakes lights, only come on when applying the brakes. Did this in 'Drive' with e-brake applied.

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I have the exact same problem. It started about 3 wks ago. I stopped driving the car since I was too busy with the holidays etc. I have about 300km's on my LS400.

At first I thought I had a badly bent rim or the wheel nuts became lose. I did the TRAC fuse, disconnected the bat. nothing changed. Mine is only on the front. When I drive forward, the steering wheel turns to the right each time the wobble happens, if I reverse, the steering wheel goes to the left. Seems like only one of the brakes is engaging. The event happens around every 6ft, forward or reverse. Prior to looking at this forum, I thought the ABS is engaging on one wheel, due to a bad sensor or something.

I tried driving the car with the brakes engaged, still happens. Is there a way to safely disable the ABS system?

you have a slightly warped rotor and a brake caliper stuck in the extended position.

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I have the exact same problem. It started about 3 wks ago. I stopped driving the car since I was too busy with the holidays etc. I have about 300km's on my LS400.

At first I thought I had a badly bent rim or the wheel nuts became lose. I did the TRAC fuse, disconnected the bat. nothing changed. Mine is only on the front. When I drive forward, the steering wheel turns to the right each time the wobble happens, if I reverse, the steering wheel goes to the left. Seems like only one of the brakes is engaging. The event happens around every 6ft, forward or reverse. Prior to looking at this forum, I thought the ABS is engaging on one wheel, due to a bad sensor or something.

I tried driving the car with the brakes engaged, still happens. Is there a way to safely disable the ABS system?

you have a slightly warped rotor and a brake caliper stuck in the extended position.

That sounds like the problem! I know one of my pistons was sticking, must now be the very end of travel. Thanks so much, I'll check it out.

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I suppose a complete brake job would be in order then? Full brake fluid change, bleeding, caliper piston kits, turned rotors, new pads... Would hate to do all that only to have it continue and throw everything off again.

This evening the issue persists. About 70% of it is in the Front Drivers side wheel, 20% in the Rear Passenger side, and 10% in the Front Passenger side. (Estimated by heat coming off the rims) I also kept a constant speed of 25mph, and the frequency of the "wobble" changed! No ABS codes, so its probably not electrical. Could all this be caused by sticking pistons and/or fluid issues?

Mind you it starts getting bad only after driving a few miles.

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I suppose a complete brake job would be in order then? Full brake fluid change, bleeding, caliper piston kits, turned rotors, new pads... Would hate to do all that only to have it continue and throw everything off again.

This evening the issue persists. About 70% of it is in the Front Drivers side wheel, 20% in the Rear Passenger side, and 10% in the Front Passenger side. (Estimated by heat coming off the rims) I also kept a constant speed of 25mph, and the frequency of the "wobble" changed! No ABS codes, so its probably not electrical. Could all this be caused by sticking pistons and/or fluid issues?

Mind you it starts getting bad only after driving a few miles.

Since I have owned my LS400 with 19,000Km's Lexus has never turned the rotors. Maybe sand them up only. They always installed factory pads.

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Have you tried putting your car up and rotating the wheels? Listen for any noise (grinding etc), and feel if there's any resistance. If your wheel's heating up sounds like a classic seizing caliper. But it could also be an abs sensor that's about to fail. Another cause could be failing wheel bearings. It's definitely not the trac because that works by cutting your throttle not engaging your brakes. And the parking brake would not affect the front wheel.

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Alright, I think parking brake can be eliminated as a cause. The issue has now moved fully to the front driver's side wheel. It is getting very hot, and when turning or moving slowly I can see the steering wheel twitch to the left in time with the pulsating I feel.

Still looking for the TRAC fuse to disconnect it and see if that prevents anything...

When you apply the brakes, do you notice any change in the wobble? When you check the wheel for temperature, do you notice any smell? If your calipers are sticking you would notice the smell of your pads burning. Also, when your making turns either in either direction, do you notice any change in the wobble and hear any noise?

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Alright, I think parking brake can be eliminated as a cause. The issue has now moved fully to the front driver's side wheel. It is getting very hot, and when turning or moving slowly I can see the steering wheel twitch to the left in time with the pulsating I feel.

Still looking for the TRAC fuse to disconnect it and see if that prevents anything...

When you apply the brakes, do you notice any change in the wobble? When you check the wheel for temperature, do you notice any smell? If your calipers are sticking you would notice the smell of your pads burning. Also, when your making turns either in either direction, do you notice any change in the wobble and hear any noise?

The wobble lessens/smooths out when I apply the brakes, but is still there. The wheel definately smells strongly of brakes. During turns, I havent really noticed alot of change, it may lessen, but once it starts it stays till the car cools off. It pretty much has to be the calipers sticking, but I dont know why the problem moved? It was entirely in rear pass. side, burning smell, hot, etc. Jacked it up, couldnt see any dragging when it freewheeled. I havent removed the front drivers side yet, but it would be more of the same I assume.

The front drivers side wheel is doing the worst right now, its getting much hotter than the rear pass. side wheel ever did, would guess the rim is over 100 degrees...

Do all the wheel brakes actuate at the same time or are they separately engaged?

Also, the wobble usually starts after I drive at least 5 miles or so.

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The kind of heat you describe can definitely warp a rotor. When travelling at 100 kph or so, if you apply the brakes you should feel a pulsation and with harder apllication the pulsation should become more pronounced. When you have the car jacked you should be able to feel the pads hit the high spot on the rotor when rotating the wheel with an accompanying rubbing sound. Try moving the wheel side to side to see if there's any play (tie rods, bearings). I'd be carefull not to drive the car until your pads are completely gone. I would also make sure not to overtorque the lugs nuts.

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  • 2 weeks later...

I took my car to a Toyota dealer to have my wobble looked at. Lexus dealer is too far away to travel in this condition. Apparently my problem is the front tires. I agree they are almost gone, but not sure they are correct. I've always used Michellin MXV 4+ front and back for over 17 years and never had this before. Can a tire go bad over night?

Thoughts?

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This is all interesting, (LS400, 91, 235,500 miles) I experience this wobble too but only if one of two things are going on -first- I cruse in 1st gear around 2,500 to 3,000 RPM 2nd or if I am traveling on a hwy for more then 20 min and at a constant speed of 85 mph or 2,200ish RPM. Unfortunately I have never checked the temp of my wheels. I was under the impression mine was a tranny issue suz the RPM combined with temp of tranny fluid. But my problem might entirely different from yours. Cuz when I check the steering wheel (letting go) at 85 mph. I drive straight (no lie for 1/5 mile+ until curve) but I get no vibration in the (free) steering wheel but feel it through the floor and set. So I guess what I’m asking you is if you just drive in 1st and still experience the same issues with your car, and is it RPM/Speed/Time related with your problem?

Don’t mean to thread jack but if anyone else has my problem or solution could you hit me up

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Well I rebuilt the front driver's side caliper, that fixed much of the problem! They all must have been at varying degrees of failure, and thus 'moved' around.

After removing the wheel, we had to dump snow on the thing to cool it down to where we could touch it, and then found the caliper was clamped on the rotor so badly it had to be pried off. One piston and one sliding bolt were completely siezed, and compressed air couldnt even budge the piston. So we just hooked it back up to the brake line and let the hydraulics pop it out. Cleaned out the rust (ruptured boot) and put in new seals (the piston boot retaining spring is a :censored: to put in), remounted and now enjoy much smoother driving!

Braking no longer has a pulsation, and is very smooth. Driver's front wheel is now cold to the touch! The rear is grabbing again, heating up, so I will rebuild that one next. I was suprized to find the rotor was not warped, indeed it would be difficult for the thickness of it! But the pads were worn asymetrically; The outer pad was about half as thick as the inner, so the pads will need to be replaced soon.

Acceleration is much better, even with the rear still dragging, wheel pulsation is gone, and mileage has gone up.

Problem solved! (Mostly) :cheers:

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Ls'92 Strange Vibration At Speed :))

one of the tires had flat spot,

rebalanced all wheels,

still vibrates

on thursday will go to a toyota service dep...

my new worry is klicking sound coming from my steering wheel (shaft) when i turn it side to side,

and there is very strange feeling as if the power steering was working only for half a turn each way and then meets some resistance in turning

wat is it???

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