TPS/APPS problems (3 Viewers)

[2manycruisers]

At this point I'm fearing a wiring issue that will be hard to trace. Mine is getting more sensitive to the point it happens in my garage when the temp in the garage is in the 40s. It goes away once it warms up for 20 minutes or so, so I suspect the problem is under the hood. Just to check, I pulled the ECM and kept it in the house overnight to keep it warm. Plugged it in in the morning at 26 degrees outside and still the same P0120. I'm going to borrow an ECM to confirm, but nearly certain that's not it. P0120 is TPS/APPS and replacing them made no difference. I assume something is causing a misread of voltage or resistance. Are there places in the wiring harness prone to heat, failure, or other problems? I'm at a total loss. Where can I find an electrical wiring diagram for a 2000 LX?

I have assumed this is unrelated, but I do have one other electrical issue. My headlights seem to flicker and bulbs don't last long (about 6-12 months).

@jackhossross have you taken yours in yet?

 

[Hu1k]

At this point I'm fearing a wiring issue that will be hard to trace. Mine is getting more sensitive to the point it happens in my garage when the temp in the garage is in the 40s. It goes away once it warms up for 20 minutes or so, so I suspect the problem is under the hood. Just to check, I pulled the ECM and kept it in the house overnight to keep it warm. Plugged it in in the morning at 26 degrees outside and still the same P0120. I'm going to borrow an ECM to confirm, but nearly certain that's not it. P0120 is TPS/APPS and replacing them made no difference. I assume something is causing a misread of voltage or resistance. Are there places in the wiring harness prone to heat, failure, or other problems? I'm at a total loss. Where can I find an electrical wiring diagram for a 2000 LX?

I have assumed this is unrelated, but I do have one other electrical issue. My headlights seem to flicker and bulbs don't last long (about 6-12 months).

@jackhossross have you taken yours in yet?

Have you replaced the TPS/APPS connectors? You can get replacements on Amazon for fairly cheap might be worth taking the connectors apart and making sure the pins are good.

 

[jackhossross]

At this point I'm fearing a wiring issue that will be hard to trace. Mine is getting more sensitive to the point it happens in my garage when the temp in the garage is in the 40s. It goes away once it warms up for 20 minutes or so, so I suspect the problem is under the hood. Just to check, I pulled the ECM and kept it in the house overnight to keep it warm. Plugged it in in the morning at 26 degrees outside and still the same P0120. I'm going to borrow an ECM to confirm, but nearly certain that's not it. P0120 is TPS/APPS and replacing them made no difference. I assume something is causing a misread of voltage or resistance. Are there places in the wiring harness prone to heat, failure, or other problems? I'm at a total loss. Where can I find an electrical wiring diagram for a 2000 LX?

I have assumed this is unrelated, but I do have one other electrical issue. My headlights seem to flicker and bulbs don't last long (about 6-12 months).

@jackhossross have you taken yours in yet?

I have not - life is getting in the way.

The comment of the of replacing the connectors @Hu1k - can you send a link?

I am not experiencing any headlight issues - however I have Morimoto HID headlights that are new as of two years ago.

 

[Hu1k]

I have not - life is getting in the way.

The comment of the of replacing the connectors @Hu1k - can you send a link?

I am not experiencing any headlight issues - however I have Morimoto HID headlights that are new as of two years ago.

APPS connector
TPS connector?

Double check the part number for the TPS connector, but I’ve done the APPS connector and that one is for sure correct.

 

[2manycruisers]

APPS connector
TPS connector?

Double check the part number for the TPS connector, but I’ve done the APPS connector and that one is for sure correct.

Thanks for the links. Were you having similar issues? Why did you replace your connector?

 

[Hu1k]

Thanks for the links. Were you having similar issues? Why did you replace your connector?

My lock clip on the APPS was broken so I replaced it. I did throw the TPS CEL but new throttle body fixed it. I threw the constant TPS code as stated earlier in this thread but disconnecting battery fixed it.

You could try taking apart the APPS and TPS and cleaning everything really well. That might help. Just make sure the APPS goes back in the same position it matters what direction it faces.

 

[thetoyotaman]

Cleared the PO1126 and waiting to see if the dialetric grease works.

 

[MongooseGA]

Has anyone had these issues in a 2003+ 100?

Occasionally, my cruise control will cancel itself and the cruise light flashes on the dash. Less frequently, mostly at higher speed, my throttle just goes dead for a second or two. It'll happen a few times in the span of a few days, then not again for months and months. I suspect these two issues may be related. I know the 03+ has the drive by wire system (unfortunately). No codes ever from this.

I'm happy to replace the parts mentioned in this thread, but hadn't noticed anything for later model trucks.

Edit, upon browsing partsouq, it looks like the options available for the 2005 are a pedal sensor (on the pedal, sold as a complete pedal assy) and the TPS, sold only (as I see on PS) as a complete TB assy.

 

[MongooseGA]

Updating for my 2005. Throttle going dead while driving has become increasingly more common in the last 2-3 weeks. I have ordered an APPS (89281-47010 is the number on the unit in my truck), a complete TB with motor and TPS, and a t-case speed sensor. I finally threw a code yester of P0722, which refers to speed sensor. I also noticed on my SG, that the truck thinks it's going 155MPH when I'm going about 35.

Will update with news here when I've installed my new parts.

 

[ffpmsam]

TPS replacement guide:

Help with TPS (Throttle Position Sensor) Replacement and Adjustment 2001LC

Hi all, I have a 2001 Toyota Landcruiser I am currently replacing the TPS (Throttle Position Sensor) (Part # 89452-30140). Reason for replacement is due to some sporadic throttle hesitation, VSC/Trac light issue with vehicle shutting off as others have posted, and I replaced the APPS last year...

forum.ih8mud.com

 

[2manycruisers]

TPS replacement guide:

Help with TPS (Throttle Position Sensor) Replacement and Adjustment 2001LC

Hi all, I have a 2001 Toyota Landcruiser I am currently replacing the TPS (Throttle Position Sensor) (Part # 89452-30140). Reason for replacement is due to some sporadic throttle hesitation, VSC/Trac light issue with vehicle shutting off as others have posted, and I replaced the APPS last year...

forum.ih8mud.com

Did this solve your issues?
I have a new OEM throttle body (includes new TPS and APPS) and I have tried a second ECU. I still have my cold weather issue so I assume it is in the harness between one of those two sensors and the ECU. Trouble shooting is difficult because the temp has to be in the low 20s or colder to have the short and I don't get that weather every day in Albuquerque.

 

[MongooseGA]

There is also a sensor on the pedal itself.

In my case I replaced the TB, APPS, and speed sensor and these issues have been fixed.

 

[jackhossross]

I am waiting for mine to act up on one of these cold days.

So replace the throttle body, APPS and speed sensor? Where is the speed sensor, is it mechanical?

 

[MongooseGA]

I am waiting for mine to act up on one of these cold days.

So replace the throttle body, APPS and speed sensor? Where is the speed sensor, is it mechanical?

There are several over the whole truck, but the one I've had difficulty with (and success replacing) is located on the transfer case, on the driver's side of the box. My speedo calibration module plugs in to it.

 

[2manycruisers]

There are several over the whole truck, but the one I've had difficulty with (and success replacing) is located on the transfer case, on the driver's side of the box. My speedo calibration module plugs in to it.

I’ve never had a VSS code, so I haven’t gone there. And the 2000 is a different drive by wire than yours. Cable from pedal to APPS on the TB.
I was thinking about replacing the entire aging engine harness but if I found the right one it’s over $2k. Way more than the $600 or so friends paid for their 80 series and 4runner

 

[MongooseGA]

I’ve never had a VSS code, so I haven’t gone there. And the 2000 is a different drive by wire than yours. Cable from pedal to APPS on the TB.
I was thinking about replacing the entire aging engine harness but if I found the right one it’s over $2k. Way more than the $600 or so friends paid for their 80 series and 4runner

You're correct about the later models being fully drive-by-wire compared to older models. But, there should still be the same speed sensor on the side of the transfer case across all years. Fortunately on the older trucks, the APPS is replaceable on its own. On mine, I had to replace the whole throttle body.

 

[2001LC]

Make sure to looking in tech stream for misfires. Especially if no DTC.

 

[2manycruisers]

I have a P0120 code, no VSS codes. I don't want to throw sensors at it with no indication they are the problem. I had seen where a cracked APPS solder joint was a culprit on a different Lexus vehicle and suspected something similar on mine. I went with a new OEM throttle body with TPS and APPS since it wasn't much more than buying the sensors separately. It made no difference. So I suspected a cracked solder joint in the ECU. I took it inside on a cold night and still had the problem, so mostly ruled that out. I was able to borrow another ECU from a friend and completely ruled out the ECU.
Anyone have experience with the Power Probe ECT 3000 short finder? Thinking that might be helpful to track an intermittent short between the sensors and the ECU. Challenge for me is having cold enough nights.

The other strange thing I've found are the intermittent conditions. If it's warm (generally above freezing) I don't have the issue. If it's moderately cold, the issue triggers after I start driving (for example, on a recent morning it was 27 or 28 degrees and I was a mile or so down the road before the CEL triggered). If it's low 20s or below, the CEL comes on at startup. Triggering after I start driving really perplexes me. Once it happened after driving nearly 20 miles on a snowy morning. In the moderate cold situations, sometimes just restarting or letting it sit a few minutes helps. On the really cold mornings, I have let it idle for 30 minutes or more and periodically restart it until it goes away.

 

[2manycruisers]

Does anyone have an electrical wiring diagram for a 2000 LX that can share the wiring for the TPS and APPS (Throttle Lever Assembly)? Tracing for a short is my next step...