BigErnz

HAIL TO THEE CLUBLEXUS GODS!!!
From murky depths, I bring forth a spin on an old favorite, perhaps one of you fine minds can help solve this increasingly head scratching mind $%^&%$#!!!!

Preface; typical CEL, VCS OFF lights, only last 15% of throttle works.... so I buy a 'tested good' complete throttle body on eBay, 'pulled from a wreck, engine ran fine' (according to description) I installed this throttle body yesterday.... super happy, no lights... everything seems good... throttle works fine.... I get about 1 mile from home, CEL comes on, followed by loss of accelerator and VCS OFF light comes on. :-\

I disconnect battery, reset codes, drive about 1 mile, same thing happens again.

Start car today, notice it happens just as the engine comes to temp. My theory is that this is when the ECU goes into closed loop, at which point, something is giving a signal to shut down VCS and the accelerator.

Any ideas what could be giving this signal? An initial scan by a friend with a Snap On code scanner, revealed Fuel Injection TPS and the Traction Control TPS were faulty.... I can not locate a second TPS... there is only 1 on the throttle body. Please help, I'm at my wits end, kinda need this car for daily driving, and I don't have deep enough pockets to deal with the Stealerships.

Thanks in advance! You guys are awesome!!!

Yamae

If I were you I would bypass the "Fuel Pump Resistor" first to check the fuel supply.
In order to bypass it, you can bypass the "Fuel Pump Relay" short-circuiting terminal 3 and 4.

BigErnz

I could check fuel; however, I don't believe fuel is an issue, the engine runs fine, and shows no symptoms of fuel starvation. I am certain that this problem occurs once the engine comes up to temp....

When I start out cold, there are no check engine lights or VCS OFF light. Once the temp gauge goes to the half-way point, check engine light comes on, accelerator response goes away, and the VCS OFF light comes on. The last 10-15% of the throttle still works, so it is still 'drivable', however, shifts are very hard, and the car seems to be running in 'limp mode'.

Thanks again in advance!

Lavrishevo

iTrader: (1)

Start with the main engine coolant temperature sensor. The lower one.

PureDrifter

iTrader: (10)

ohm out the wires from the throttle body to the ECU and from the ECU to the pedal.

I'm guessing you have a nicked wire somewhere from the ECU to the TB which is causing the intermittent issues.

Lavrishevo

iTrader: (1)

I don't think it's intermittent from what he said. Does it happen exactly when the car gets to operating temperature or somewhere in-between? Probably was nothing wrong with the original TB in the first place. The last 15% is part of the limp mode.

It is more of a consistent time of driving before the ecu puts it in limp mode? The TPS on the car does need to be adjusted correctly. There is only one TPS on the car so look at that closely. Traction is tied into the wheel speed sensors mainly but it obviously control's throttle body as well.

BigErnz

Something was wrong with the original throttle body, I'm quite sure.... let me give you the ugly history lol

Originally, the check engine light, and VCS OFF light would come on, with a message 'check VCS'... this seemed to happen on occasion if you didn't let the car heat up enough. After about a month of this, it would also lose throttle response. you could only use the last 15% of the throttle. This got progressively worse until it was an every-day ordeal, NEVER getting throttle response until that last 15% of the cable.

Fast forward 6 months, car won't start. Cranks and cranks, however, if I floor the gas pedal, I can get it to start, BARELY runs, and you have to rev it like crazy to keep it running... after some research, I decide to replace the TPS. Rock auto showed 2 (1 for fuel injection, 1 for traction control) I bought both, figured I would start with the cheaper of the 2... replaced the TPS, and the car started fine; however, I was back to the same 'CEL and VCS OFF light' situation. Again, NEVER any throttle response until the last 15% of cable.

I now figure, either the throttle control motor, or the accelerator pedal sensor, or possibly both have failed.... I find a 'known good' throttle body on eBay for $210 (YaY!) all sensors are still intact, the donor car was in an accident, however, the engine started and ran fine. (According to the seller, who has very reputable feedback BTW)

I install said throttle body, car starts fine, runs fine, no lights are on!! All looks well!!! I leave her run for awhile, she's up to temp, still no lights, decide to go for a test drive.... I get about 1 mile from home, CEL comes on, throttle response goes away, and VCS OFF lamp is back on... FML!!! I limp it to the gas station, put in a fresh tank, open the hood, check throttle body connections, everything seems tight... Start the car, CEL and VCS OFF lights are on, however, I have throttle response! Again though, about 1 mile from gas station, I lose throttle response ans have to limp home.

I disconnect the battery to reset the ECU, start the car, no lights again.... go for a drive... about 1 mile, same thing happens again. Pissed off, I go back home and let her sit over night.

I go out in the morning, start her up.... no lights?? Go for a test drive.... everything seems fine.... I go over a mile.... no problem.... running smooth as can be!!!! Realize how much I've missed old girl! Then.... JUST as it comes to temperature (my LS always runs dead middle of the heat gauge) JUST as it reaches the middle of the temp gauge, CEL and VCS OFF lights come on, and no throttle response. AARRRRGGGGGHHHHHH!!!!!!!!! I have repeated this test 2 more times to the same avail.....

My assumption is that the vehicle probably enters closed loop operation at this point.... and something, somewhere, for some reason, is not in order with what the ECU expects, and it is shutting down the throttle. I'm not sure where to go from here. My friend is supposed to be coming through with his code scanner again soon, so I'm hoping he can give me some helpful info, I will share what we find here as well.

Thanks again to all those tossing me ideas and help!!!

BigErnz

Assuming I am drawing a lot of blank stares? lol.... was hoping I'm not alone in this boat, but it's not looking too good so far....

BigErnz

Okay, so I got my buddy's scanner, and I am getting code p1128.... I looked through the forum here, and am not finding too much useful information. Hopefully someone has some good guidance? I saw one successful story of someone who replaced their positive battery connector, but mine looks fine, not corroded or anything, very tight connection. PLEASE HALP!!!

Legender

Did you see this thread...?

https://www.clublexus.com/forums/gs-...8-bad-tps.html

it's on a second generation GS but may give you some ideas...

Rust Heap

Did you ever figure out exactly what was causing your issues? My '96 is currently at the very beginning stages of what you are going through. I have no codes, no indicator lights illuminated, just a very intermittent 0 throttle response and no start.

LScowboyLS

these are precisely the early signs of ECU capacitor failure, a known issue, and especially common on 93-97 models

Yamae

The code P1128 means no movement of the throttle valve for more than 0.5 sec.

This is caused by the failed throttle body or the failed ECU. Sometimes the cable between them causes the problem but the biggest issue I knew was the motor inside of the throttle body not working well.

When the motor is failed and consuming too much current, this sometimes causes the additional problem at the drive transistor in the ECU too. Below is just my assumption but I worry that your original throttle body had the motor problem. It was stuck and consumed too much current. Then you replaced it to another good one. But the already semi damaged drive circuit in the ECU by the too much current could not survive long. The partial damage sometimes may cause a new problem to the motor too.

Without measuring the actual one, I cannot say above with my confidence but I had several experience of damaged drive circuits in the ECU caused by the units driving. Some were motors and some were solenoids or coils. The most ECU failures were caused by the capacitors but there were failures of semiconductors too.