New owner: Vibration, TRAC-OFF Light, and More!
12-26-07, 03:14 AM
#31
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I had a similar problem that lead to having a clogged injector , i ran a full can sea foam in 1/4 tank to clean quickly and it has since cleared up the issue which i thought was ignition related. Either a coil or injector , so for me it was the injector by process of elimination for nothing more than a can of sea foam .
I assume the throttle body is also clean. Also disconnecting the vacuum actuator for the egr will not help if it is sticking. So by you saying nothing changed that may be a problem also.
For the rear brake problem i would look at you parking brake shoes and cable not eh rotors caliper first. It may be still sticking though as it did go away for a bit , next time pull the caliper off and before you push the piston back in spray some pb blaster inside the rubber seal around the piston to lube it.
I assume the throttle body is also clean. Also disconnecting the vacuum actuator for the egr will not help if it is sticking. So by you saying nothing changed that may be a problem also.
For the rear brake problem i would look at you parking brake shoes and cable not eh rotors caliper first. It may be still sticking though as it did go away for a bit , next time pull the caliper off and before you push the piston back in spray some pb blaster inside the rubber seal around the piston to lube it.
12-26-07, 08:22 AM
#32
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Your Trac Off light woes... I had a very similar problem with my 94 LS that I couldn't figure out. After startup, the Trac Off light would come on and stay on yet my traction control still functioned. I couldn't get a code off of it either. I finally took it to the Lexus dealership and they diagnosed it to be a $1300 ECU that was bad. That was their theory since they couldn't get a code. I was ready to pay for the ECU, but they didn't have it in stock... a blessing in disguise.
In the meantime, I discovered through an oil change that I had a very slight coolant leak but couldn't find the location. Over the course of a few months, it progressively got worse and I took it into my indie mechanic to find the leak and fix it. He found the water pump leaking, so I had him replace it and lo' and behold... the Trac Off light did not come on during the ride home and has functioned properly ever since. My guess is that there was some sensor monitoring coolant system pressure that caused the Trac Off light to come on.
My advice would be to make sure your coolant system is tight through and through and you don't have a leak somewhere. Also, the OEM coolant is a reddish brown color and that may be what you found leaking. Even though you have the green stuff in your reservior, you may have the reddish brown stuff circulating through your engine. You can find this out by unscrewing the coolant fill bolt near where your upper coolant hose connects to the engine block and checking the color of your coolant. Good luck.
In the meantime, I discovered through an oil change that I had a very slight coolant leak but couldn't find the location. Over the course of a few months, it progressively got worse and I took it into my indie mechanic to find the leak and fix it. He found the water pump leaking, so I had him replace it and lo' and behold... the Trac Off light did not come on during the ride home and has functioned properly ever since. My guess is that there was some sensor monitoring coolant system pressure that caused the Trac Off light to come on.
My advice would be to make sure your coolant system is tight through and through and you don't have a leak somewhere. Also, the OEM coolant is a reddish brown color and that may be what you found leaking. Even though you have the green stuff in your reservior, you may have the reddish brown stuff circulating through your engine. You can find this out by unscrewing the coolant fill bolt near where your upper coolant hose connects to the engine block and checking the color of your coolant. Good luck.
12-26-07, 06:13 PM
#33
Lexus Test Driver
check your grounds buddy! I havefound that a loose or weak ground can cause some hesitation. you should also consider adding a grounding kit. Does wonders for the electrical system. After you are done reset the computer and also fix the fuel pulsation damper or eliminate it like i did.
12-27-07, 07:22 PM
#34
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Ah, a second voice to ground! I have been told to look at the grounds as well, so that will be my next attack. The issue is either electrical or fuel, which doesnt really narrow it down 
What effect does removing the damper have?
What effect does removing the damper have?
01-05-08, 11:42 PM
#35
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Not a direct battery-chassis ground issue that I can tell.
The other day, the issue with the wheel's brakes "dragging" MOVED to the driver's side!!! This must be an electrical issue, as I have a constant TRAC-OFF going when the engine starts. It has however moved back to the passenger rear wheel again.
Apparently, I was checking the codes wrong, you must jumper Tc and E1 to get the TRAC codes, and the TRAC light in the speedo does the code readout (not the TRAC-OFF light). All I get is code 51, which most say means you arent in Neutral, A/C is on, throttle at idle, etc, but all apply!
Officially, it is "Problem in engine control system" specifically "Engine Malfunction Detection Circuit". Then it says: "If the trouble (trouble which causes CHECK engine warning light to light up) occurs in the engine control system, this circuit senses the trouble and prohibits TRAC control."
The only issue with this is I NEVER GET A CHECK ENGINE LIGHT!!! Something is screwy with the electrical... I will need to check the harnesses for all the ECUs, anybody know how to remove the panel to get to them without doing damage to the interior?
I have noticed, on occasion, that going downhill with the cruise on, the car will seem to periodically slow down, like the brakes are being gently pressed for about 3 seconds, released for 3 seconds and so on. Does cruise have braking control?
Further, in an effort to diagnose the engine troubles, I looked into the waveforms for the ignition system. I have fairly certainly ruled out the coils and igniters, by connecting the oscilliscope to the coil output and the igniter output. Now, the igniters are getting fairly clean signal from the ECU, with perhaps a little noise here and there, but the odd thing is, both the waveforms for coil 2 and the signal to that coil have an abrupt dropoff during the spark burn/dwell which causes a secondary peak. I suspected the igniter, so I swapped the connectors on the igniters. The problem moved with the connector!!! So this tells me wiring? or ECU signal. I then compared the ECU signals for both Igniters, side by side... NO major differences???? What would cause the odd primary and secondary waveform without influence from the ECU or Igniters???
The other odd thing, is that in idle, the waveforms for either coil (but NOT the signals from the Igniters TO the Coils) vary widely, bouncing around and losing coherence. When the engine is slowly revved, the coil outputs become smoother and more coherent, looking much like a regular ignition coil's output. This then corresponds to the engine running smoother. Does this mean 100% its the coils??? I dont have a means to check the current on the scope, so I dont know how that is doing, but would anything other than ECU, Igniter and Coil affect the waveform? Plugs, Wires, wires from coil to igniter?
I can post waveforms if anyone would wish to look them over.
The other day, the issue with the wheel's brakes "dragging" MOVED to the driver's side!!! This must be an electrical issue, as I have a constant TRAC-OFF going when the engine starts. It has however moved back to the passenger rear wheel again.
Apparently, I was checking the codes wrong, you must jumper Tc and E1 to get the TRAC codes, and the TRAC light in the speedo does the code readout (not the TRAC-OFF light). All I get is code 51, which most say means you arent in Neutral, A/C is on, throttle at idle, etc, but all apply!
Officially, it is "Problem in engine control system" specifically "Engine Malfunction Detection Circuit". Then it says: "If the trouble (trouble which causes CHECK engine warning light to light up) occurs in the engine control system, this circuit senses the trouble and prohibits TRAC control."
The only issue with this is I NEVER GET A CHECK ENGINE LIGHT!!! Something is screwy with the electrical... I will need to check the harnesses for all the ECUs, anybody know how to remove the panel to get to them without doing damage to the interior?
I have noticed, on occasion, that going downhill with the cruise on, the car will seem to periodically slow down, like the brakes are being gently pressed for about 3 seconds, released for 3 seconds and so on. Does cruise have braking control?
Further, in an effort to diagnose the engine troubles, I looked into the waveforms for the ignition system. I have fairly certainly ruled out the coils and igniters, by connecting the oscilliscope to the coil output and the igniter output. Now, the igniters are getting fairly clean signal from the ECU, with perhaps a little noise here and there, but the odd thing is, both the waveforms for coil 2 and the signal to that coil have an abrupt dropoff during the spark burn/dwell which causes a secondary peak. I suspected the igniter, so I swapped the connectors on the igniters. The problem moved with the connector!!! So this tells me wiring? or ECU signal. I then compared the ECU signals for both Igniters, side by side... NO major differences???? What would cause the odd primary and secondary waveform without influence from the ECU or Igniters???
The other odd thing, is that in idle, the waveforms for either coil (but NOT the signals from the Igniters TO the Coils) vary widely, bouncing around and losing coherence. When the engine is slowly revved, the coil outputs become smoother and more coherent, looking much like a regular ignition coil's output. This then corresponds to the engine running smoother. Does this mean 100% its the coils??? I dont have a means to check the current on the scope, so I dont know how that is doing, but would anything other than ECU, Igniter and Coil affect the waveform? Plugs, Wires, wires from coil to igniter?
I can post waveforms if anyone would wish to look them over.
11-10-13, 02:51 PM
#36
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Not a direct battery-chassis ground issue that I can tell.
The other day, the issue with the wheel's brakes "dragging" MOVED to the driver's side!!! This must be an electrical issue, as I have a constant TRAC-OFF going when the engine starts. It has however moved back to the passenger rear wheel again.
Apparently, I was checking the codes wrong, you must jumper Tc and E1 to get the TRAC codes, and the TRAC light in the speedo does the code readout (not the TRAC-OFF light). All I get is code 51, which most say means you arent in Neutral, A/C is on, throttle at idle, etc, but all apply!
Officially, it is "Problem in engine control system" specifically "Engine Malfunction Detection Circuit". Then it says: "If the trouble (trouble which causes CHECK engine warning light to light up) occurs in the engine control system, this circuit senses the trouble and prohibits TRAC control."
The only issue with this is I NEVER GET A CHECK ENGINE LIGHT!!! Something is screwy with the electrical... I will need to check the harnesses for all the ECUs, anybody know how to remove the panel to get to them without doing damage to the interior?
I have noticed, on occasion, that going downhill with the cruise on, the car will seem to periodically slow down, like the brakes are being gently pressed for about 3 seconds, released for 3 seconds and so on. Does cruise have braking control?
Further, in an effort to diagnose the engine troubles, I looked into the waveforms for the ignition system. I have fairly certainly ruled out the coils and igniters, by connecting the oscilliscope to the coil output and the igniter output. Now, the igniters are getting fairly clean signal from the ECU, with perhaps a little noise here and there, but the odd thing is, both the waveforms for coil 2 and the signal to that coil have an abrupt dropoff during the spark burn/dwell which causes a secondary peak. I suspected the igniter, so I swapped the connectors on the igniters. The problem moved with the connector!!! So this tells me wiring? or ECU signal. I then compared the ECU signals for both Igniters, side by side... NO major differences???? What would cause the odd primary and secondary waveform without influence from the ECU or Igniters???
The other odd thing, is that in idle, the waveforms for either coil (but NOT the signals from the Igniters TO the Coils) vary widely, bouncing around and losing coherence. When the engine is slowly revved, the coil outputs become smoother and more coherent, looking much like a regular ignition coil's output. This then corresponds to the engine running smoother. Does this mean 100% its the coils??? I dont have a means to check the current on the scope, so I dont know how that is doing, but would anything other than ECU, Igniter and Coil affect the waveform? Plugs, Wires, wires from coil to igniter?
I can post waveforms if anyone would wish to look them over.
The other day, the issue with the wheel's brakes "dragging" MOVED to the driver's side!!! This must be an electrical issue, as I have a constant TRAC-OFF going when the engine starts. It has however moved back to the passenger rear wheel again.
Apparently, I was checking the codes wrong, you must jumper Tc and E1 to get the TRAC codes, and the TRAC light in the speedo does the code readout (not the TRAC-OFF light). All I get is code 51, which most say means you arent in Neutral, A/C is on, throttle at idle, etc, but all apply!
Officially, it is "Problem in engine control system" specifically "Engine Malfunction Detection Circuit". Then it says: "If the trouble (trouble which causes CHECK engine warning light to light up) occurs in the engine control system, this circuit senses the trouble and prohibits TRAC control."
The only issue with this is I NEVER GET A CHECK ENGINE LIGHT!!! Something is screwy with the electrical... I will need to check the harnesses for all the ECUs, anybody know how to remove the panel to get to them without doing damage to the interior?
I have noticed, on occasion, that going downhill with the cruise on, the car will seem to periodically slow down, like the brakes are being gently pressed for about 3 seconds, released for 3 seconds and so on. Does cruise have braking control?
Further, in an effort to diagnose the engine troubles, I looked into the waveforms for the ignition system. I have fairly certainly ruled out the coils and igniters, by connecting the oscilliscope to the coil output and the igniter output. Now, the igniters are getting fairly clean signal from the ECU, with perhaps a little noise here and there, but the odd thing is, both the waveforms for coil 2 and the signal to that coil have an abrupt dropoff during the spark burn/dwell which causes a secondary peak. I suspected the igniter, so I swapped the connectors on the igniters. The problem moved with the connector!!! So this tells me wiring? or ECU signal. I then compared the ECU signals for both Igniters, side by side... NO major differences???? What would cause the odd primary and secondary waveform without influence from the ECU or Igniters???
The other odd thing, is that in idle, the waveforms for either coil (but NOT the signals from the Igniters TO the Coils) vary widely, bouncing around and losing coherence. When the engine is slowly revved, the coil outputs become smoother and more coherent, looking much like a regular ignition coil's output. This then corresponds to the engine running smoother. Does this mean 100% its the coils??? I dont have a means to check the current on the scope, so I dont know how that is doing, but would anything other than ECU, Igniter and Coil affect the waveform? Plugs, Wires, wires from coil to igniter?
I can post waveforms if anyone would wish to look them over.
11-10-13, 07:24 PM
#37
Lexus Champion
what year LS and what codes are you getting?
11-11-13, 12:49 PM
#38
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1990 ls400
Throwing codes 13, 45, 51, and 68.
Only symptoms so far is that the car seems to go into limp mode when the tires spin. So by that I mean the car will have limited power, it will not kick down and the trac light is on as well as the trac off light is on.
The Trac off light is allways on and pressing the trac button dosent change anything.
Anouther symptom is that at higher speeds (80-90) the car starts cutting out like it has a speed limiter.
Throwing codes 13, 45, 51, and 68.
Only symptoms so far is that the car seems to go into limp mode when the tires spin. So by that I mean the car will have limited power, it will not kick down and the trac light is on as well as the trac off light is on.
The Trac off light is allways on and pressing the trac button dosent change anything.
Anouther symptom is that at higher speeds (80-90) the car starts cutting out like it has a speed limiter.
11-11-13, 12:56 PM
#39
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Forgot to mention sometimes the trac light will shut off but when it stays on I have to shut the car off to get it to reset or shut off. Power is good after that. Brake fluid level is good, the power steering has a slight leak and I replaced the front brake pads hoping this would help.
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