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

azzuri

New Member
Joined
May 19, 2013
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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:
 
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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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I had exactly the same thing but removing my Steinbauer P-Box chipped ECU fixed it - you not have anything like that in it?
 
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.
 
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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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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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?
 
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?
 
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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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!
 
Check the wiring on the shutter valve - have a good look there is a cover that wears through the wiring harness took me three week to find it, gut once fixed was OK again
 
Funnily enough that is exactly what had happened to mine too. I fixed the wire and it has not played up since!
 
The number of people that front up and buy a new peddle instead of servicing the old one always surprises me
 
Hi all,
Same issue with mine.
Where is the “shutter valve” located. Excuse my ignorance!!!
Thanks
 
Hi all,
Same issue with mine.
Where is the “shutter valve” located. Excuse my ignorance!!!
Thanks
The shutter valve is a butterfly valve on the intake, next to the heater grid. Just to the right (starboard) of the engine top. On the early years (4 sp auto) it was vacuum powered via a solenoid valve (controlled by engine ECU). On the newer ones it was electric, controlled directly by the Engine ECU.
The vacuum driven would sometimes develop a leak, and the electric type would sometimes develop a broken conductor in the cable just next to the valve.

What issue do you have? The most common fault with the throttle on the 1HD-FTE may be a faulty idle switch on the accelerator pedal.
 
Hi Uhu,
Thanks for the reply!
Engine light goes on and then limp mode (sometimes right after i start, othertimes while driving). After restarting its good till the next time.
Mechanic says i have to replace the throttle butterfly (electric on mine). £275 from Toyota. Had the same issue 2 years ago and mechanic (different mechanic, same workshop) then said it was wiring which he fixed at the time.
How would i know if its the idle switch?
Thanks & have a good weekend
 
Read the codes. If limp, then = codes.
If we are talking about the same valve on the intake, then it is not required for the engine to run. It is only a safety shut-down valve for stopping the engine safely in all conditions, like when overheating, a broken turbo shaft, or another condition where the engine is running on engine oil vapour. As long as the valve is open, the engine will run.

More common faults when limping, are with the IP, EDU, or the throttle pedal. Read the codes.

The idle switch on the throttle pedal is a known problem, and it's easy to take the whole pedal assembly out and measure the switch. Easy to spot as well, when you have the pedal assembly in hand. There is only a wire and a spring (mechanical parts) and a throttle position sensor, and an idle switch which tells the ecu that the pedal is not pressed at all. When the idle switch says "No throttle signal" and the position sensor says "Throttle pedal depressed", the gets ecu gets confused and gives up.
 
Thanks Uhu.
Think i might have found the problem, or part of it.
Will take the pedal assembly out as well
 

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Update - electric wire soldered together in the plastic housing. Engine light not come on again. Touch wood!!
 
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