well out of nowhere my gs400 died on me. it all started two nights ago when i started the car up and it had a really rough idle. it would die when pressed the gas. finally it got going ok and drove home on the freeway just fine. Soon as i came to stop it would die if throttle was not kept to 1k..

Next day i was gettin prepared to tow car to my friends shop. we both work on our own cars. Car made it to shop. we found couple cracked vacuum hoses. fixed those. found the actual tube from intake to the airbox had somehow slid off. Fixed that. Started the car up and she ran just fine.

he hooked up his bluetooth obd2 and with car guage and torque everything looked good. Drove the car back to my apt. it drove fine around city and freeway. Went inside for hour. came out to go to work and car started and died....

after testing the tps wiht ohm meter it seemed close enough but i bought a new one from lexus anyways. installed it per specs. started car up... still dies. The car will sometimes hunt for idle going up past 1k.. then dropping to zero. almost die the shoot up again. But it always dies within a minute.

IF i press the pedal all the way in to engage the throttle cable it instantly dies. Im currently looking for the exact specs for testing the maf. Also i know i have to test the apps.

when the car is hunting for idle when i press the pedal i get no throttle response at all. If pressed all way in the car dies when cable opens the throttle plate.


i Just now recieved cel lights too. i will have to pull those in the morning. Other than checking the maf and the apps with ohm meter what else does anyone think this could be?

Ill update after cel are pulled.

 

I would check the idle control valve/motor.

 

well here is the codes i pulled


p0100 mass or volume air flow circuit A

p0110 intake aire temperature sensor 1 circuit

p1125 throttle control motor circuit malfunction

p1128 throttle control motor lock malfunction

p1345 vvt sensor / camshaft position sensor circuit malfunction bank one

 

Suggests the MAF isn't completely plugged in. They're such odd errors, it almost looks like something cut into your harness, Wonder if you're having a mice problem? Might want to pull the engine cover off.

 

my buddy who is a lexus guru also said he thinks its in the harness.. ill have to wait for the rain to stop before i start tearing into that... harness or ecu?

 

Sound like something is shorted out in your harness bro.

 

the maf ohms out good at 68 degrees in my apt... yes i too think there is either something with harness or... ecu.


problem is i need to now hunt through the harness....

still waiting for rain to stop to check aps sensor by cable and throttle control motor

 

I had a simular problem like that about 2 months ago on my gs3. I replace my throttle control motor, but I only got the cel, vsc, and vsc off light.

 

Sometimes a bad ground will cause weird unrelated cels like this too.

 

update

INSPECT THROTTLE CONTROL MOTOR for operating sound.

(1) Turn the ignition switch ON.
(2) When turning the accelerator pedal position sensor
lever, check the running sound of the motor. Also,
check that there is no friction sound.
If operation is not as specified, check the throttle control motor,
wiring and ECM.
(a) Disconnect the throttle control motor connector.
(b) Using an ohmmeter, measure the resistance between terminal
3 (CL–) and 4 (CL+).
Resistance: 4.2 – 5.2 W at 20°C (68°F)


(c) Using an ohmmeter, measure the resistance between terminal
1 (M+) and 2 (M–).
Resistance: 0.3 – 100 W at 20°C (68°F)


If the resistance is not as specified, replace the throttle control
motor.
(d) Reconnect the throttle control motor connector.







INSPECT THROTTLE POSITION SENSOR
(a) Disconnect the throttle position sensor connector.
(b) Using an ohmmeter, measure the resistance between terminals
VC and E2.
Resistance: 1.2 – 3.2 kW at 20°C (68°F)


If the resistance is not as specified, replace the throttle position
sensor.
(c) Reconnect the throttle position sensor connector.

INSPECT ACCELERATOR PEDAL POSITION SENSOR
(a) Disconnect the accelerator pedal position sensor connector.
(b) Using an ohmmeter, measure the resistance between terminals
VC and E2.
Resistance: 1.2 – 3.2 kW at 20°C (68°F)


If the resistance is not as specified, replace the accelerator pedal
position sensor.



also per a pdf i checked this the volts did rise as i moved the apps on the thorttle body








now long story short after reinstalling everything.. hooking up my scan tool and setting the tps to 15% ... resetting all the codes now the car runs and i have full throttle response on the pedal..


whats weird is before i had reset the codes when i would turn the car on and move the cable the throttle control motor would move the throttle plate for a second.. then stop. this happend over and over each time i turn the car off then back on. i would get hte motor to move plate for split second.. then nothing.

im still hoping this is not an intermittent problem. If everyone could double check my ohm readings and make sure everything looks good. i also opened up the harness from these 2 sensor and motor and checked the wires back to ecu. everything looks fine.

 

Good trouble-shooting. Nice to see. Most people just slap on parts.