dabofoppo

Hi all,

New member here. I'm having an intermittent issue with my 2001 GS430 that I'm looking for help with. Based on this thread, I'm fairly sure the APP (accelerator pedal position sensor) needs to be replaced. I don't have a CEL, and the problem is intermittent ubut very annoying.

I've priced a new APP (part number 78010-30030) with a local Lexus dealer, priced at €178. Before I go ahead and order the part, I have a few questions:

• Where is the sensor located - on the pedal itself or at the throttle body?
• I think the part number above might be the whole accelerator pedal assembly (including the sensor)... can I order just the sensor? (if so, what's the part number - could this be it?)
• Can I swap it over myself, or do I need to get it calibrated by a Lexus dealership?

All advice appreciated

GS400V8

iTrader: (4)

Well from that thread and others, it seems like other stuff fail in the throttle body before that sensor in the accelerator pedal does. There are three components here with the GS430:
1) APP by gas pedal
2) APS on passenger side of throttle body (electric motor)
3) TPS on driver side of TB (physically adjustable potentiometer by two screws that sets voltage, affects idle)

I've done alot of research on these and some were fixed by repairing/soldering the terminals inside these motors, some were fixed by adjusting the TPS, or replacing the TB with a used one off eBay, which replaces two sensors at once. Very few were fixed by the APP, although it is possible sometimes. The GS300/400 are very similar, except for a cable replacing number 1) APP, and had very similar problems.

If your dealer is cool, you could buy the APP, and ask if you can return it if it is undamaged and you have your receipt. Put it on, see if it solves the problem, and if not, return it. Then you'll know it is most likely one of those common causes on the TB.

dabofoppo

Thanks for the help. Some follow up questions...

Any chance you have links to these repairs?

Again, any links to how to do this before I start googling?

Any idea what the part number is for a GS430?

GS400V8

iTrader: (4)

There was never really any write ups on those, they just pulled the motor assemblies off the throttle bodies, opened them, removed the old solder and re-flowed new joints.

The TPS adjustment is basically done by loosening the two screws and then slightly rotating it back and forth while measuring voltage through a multimeter or scan tool. Some have had luck with doing it strictly by trial and error and engine RPM but it is a very sensitive adjustment. I'll attach a PDF file that was used for the non-VVTi motors but the procedure is the same.

A GS430 Throttle Body assembly is 2203050160 and comes with both sensors on it. On eBay just now, 18 results pulled up in the USA, 21 outside of the USA, with one even in Tipperary, Ireland

PDF on TPS Procedure:

dabofoppo

Finally got around to fitting a used throttle body on the GS430 at the weekend. No joy. Same issue. Just after startup and at random occasions, the throttle pedal doesn't respond to the first inch of travel.

As before, I've priced a new APP (part number 78010-30030) with a local Lexus dealer, priced at €178. Before I go ahead and order the part, I think the part number above might be the whole accelerator pedal assembly (including the sensor)... can I order just the sensor? (if so, what's the part number - could this be it?)

GS400V8

iTrader: (4)

Well you only have two options left now which is the APP, and TPS but your throttle body probably had the TPS attached already. You can calibrate it but be careful. Highly doubt that you bought a second bad one so it might be the APP.

The APP is not available to buy just with the sensor unless you somehow removed it from a junk vehicle.

No, the link you pictured on eBay is the TPS sensor that has 4 pins. The APP has 6 pins.

dabofoppo

Yep the TPS was replaced with the new (second hand) throttle body.
I think I've sourced a second hand pedal & sensor - just confirming what year the car it came from is before buying.

Thanks for all the help so far

dabofoppo

Quick update on this. The problem completely went away, so it appears to have been solved by replacing the throttle body (and the sensors attached to it) with a second hand one.
Thanks again to GS400V8 for suggesting this solution. Worked out to be a very cheap option

MedicalDoc

Congrats on the fix!!