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4.2 litre diesel - going to limp mode and tearing my hair out...

azzuri

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Joined
May 19, 2013
Messages
3
Hi Folks,


I've recently purchased (3 months ago) a 2003 Toyota commercial vehiclewhich runs with a 4.2 litre Land Cruiser diesel engine, and it has me pulling my hair out at the moment, hence why I'm here. Although not strictly a Land Cruiser, the engine/electrics are the same, and this is where the problem lies.

The engine management light comes on intermittently (normally at lowrevs/speed), and the engine goes in to limp mode. It happens quite randomly, and when it does, turning off and on again resets the ecu and we're off as normal.....until the next time it happens, could be 5 minutes, could be 5 days.

We had oil/fuel filters changed and service done, all the basics before the expensive stuff.

Took it to a diagnostics specialist who could only diagnose when the light was on, as it wasn't storing the fault, finally it happened and although I wasn't present at the time to see the fault code, he mentioned something to do with 'Throttle Idle Sensor' and perhaps the 'Potentiometer'.

There is a simple brake switch under the throttle pedal which controls the exhaust brake when the pedal is not pressed, and you can't buy this separately from Toyota, had to buy the entire new Throttle assembly from Toyota @ £440 + fitting which I was assured would solve the problem.

Two days later and the problem has presented itself once again, 15 minutes after startup, going in to limp mode and unsure where to go from here?

Readyfor just driving it in to the sea (not sure whether I'll get out itor not after this!).

A crate of beer to whomever can help me solve this, 3 months of to-ing and fro-ing to so-called specialists has me ready to give up and take a massive hit on the vehicle. :icon-cry:
 
Last edited:

uHu

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Mar 7, 2010
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2,142
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norway
Is this the 1HD-FTE? With the same IP, EDU and ECU? And the same fly-by-wire engine control?

You mention throttle and acc-pedal... What was changed?
There is the accellerator position sensor, the throttle position sensor, and the throttle control motor, iirc - that could be involved.

Another common issue, which was resolved around 2003, is the connector betwen the EDU and the IP/Spill control valve.
Edit: BTW: Which turbo does it have?
 
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grahamnaismith

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Joined
Mar 17, 2010
Messages
21
I had exactly the same thing but removing my Steinbauer P-Box chipped ECU fixed it - you not have anything like that in it?
 

azzuri

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Joined
May 19, 2013
Messages
3
Is this the 1HD-FTE? With the same IP, EDU and ECU? And the same fly-by-wire engine control?

You mention throttle and acc-pedal... What was changed?
There is the accellerator position sensor, the throttle position sensor, and the throttle control motor, iirc - that could be involved.

Another common issue, which was resolved around 2003, is the connector betwen the EDU and the IP/Spill control valve.
Edit: BTW: Which turbo does it have?

I'm not sure the version number of the engine, all I know is that it is exactly the same 4.2 litre diesel that is/was available in the Land Cruiser of the same year. The vehicle is 2003, I'm not entirely sure of the turbo that is in the bus, although I'd be surprised if it was any different to the one in the Land Cruiser model of the same year.

The entire throttle assembly was changed, which includes accelerator pedal, accelerator position sensor and lots of different switches/cables, it's an electronic throttle.
 

Doodle

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Aug 20, 2012
Messages
939
Garage
I'm presuming it's a Toyota Optimo/Coaster?

If wikipedia is to be believed, it's probably a 1HZ Turbo motor, which wasn't fitted to the 03 Amazon (in this country at least)
 
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Shayne

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Feb 2, 2013
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14,043
I'm a non techcinal kind of fella and for me electric things that switch themselves on and off when they shouldn't is always the result of a chaffed wire allowing a circuit to be broken or activated whenever it touches upon a metal surface . If you can find it its a tuppence fix .
 
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azzuri

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Joined
May 19, 2013
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3
I'm presuming it's a Toyota Optimo/Coaster?

If wikipedia is to be believed, it's probably a 1HZ Turbo motor, which wasn't fitted to the 03 Amazon (in this country at least)


Yeah it's an Optimo V, just wondering if there are any Toyota/Electronic specialists in Scotland we could talk to to have a look at it?
 

hobie1

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Aug 7, 2015
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philippines
Limp mode

Hello,


Was anyone able to fix this? I have exactly the same problem. I already cleaned the Throttle Position Sensor, Changed the Coolant temperature sensor but I still get the limp mode everday. Quick solution is to turn the engine off then start again.

Hope there is a solution. I have tried almost every research on the internet already.


Thanks!

Yeah it's an Optimo V, just wondering if there are any Toyota/Electronic specialists in Scotland we could talk to to have a look at it?
 

Jackie5228

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Jul 9, 2021
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brunei
I been searching for months over the Internet over the intermittent limp mode issue on my LC100 1HD-FTE. It's exactly the same as Assuri's described. I got it fixed for free or probably under $1.

Honestly, We found it out by accident. The original "accelerator pedal switch STOPPER" had broken overtime so the switch is not working properly causing the intermittent limp mode. We put on a rubber stopped and the issue never come back *finger cross*. I believe many people would change to a brand accelerator set which is not necessary for my case. Please refer picture attached on the stopper I'm referring to. Hope this helps all the LC users out there.
 

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kcslb92

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Nov 23, 2021
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australia
Hey guys,

Can you please elaborate on this a bit further? If you can take another picture of what you replaced that would be fantastic please! I’ve got the same issue with mine and have inspected it, it looks the same as in your image.

Cheers!
 
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