96 300 TDI Auto Throttle Position Sensor

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armalites

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Hi all, I have some useful info. This only applies to 300TDIs with electronic pump
My wife has an Auto 300 TDI which has the electronic pump and hence is fly by wire. When we got it, it took a bit of cranking to start from cold and gave a little white smoke. I tweeked the timing and it started perfect. Unfortunately this highlighted an intermittant engine check light as the increased power obviously gave a different rest postion for a given speed. This gradually got worse and we got hesitation and fluffing at crusing speed. This seemed to be due to worn TPS(throttle position sensor) as it only happened at a particular pedal position, it's done 170K. This is where the story gets interesting. Took the sensor out which is fiddly to say the least. It's made by Bosch. I phoned Landrover, £690 +vat!!!!! I then phoned some Bosch agents found on the Bosch website. My local one quoted me £170 +vat. I ordered it and fitted today. Everything is fine now. I didn't tell them how much Landrover were charging for obvious reasons!! Tried surfing for the number below without luck apart from a couple of sites in a foreign language. If you disconnect the connector in the engine bay the engine check light will light and revs will rise to 1200. I think this is classed as limp home mode. Only problem there is it's only later 300 auto that have the electronic pump so the box probably won't get out of first!!
The Bosch part number is 0 205 001 021.
 
could you tell me the location of the sensor is it on the pedal or the pump, would be gratefull as mine has started todo this exact problem, many thanks
 
Another part of the glorious EDC system.....much nicer than getting the pump recon'd, which is the advice I have had on occassion for this problem.

I have the cold start problem which I had put down to an EDC fault....but replacing the coolant temp sensor that normally solves this didnt work.

Just recently the 98 auto has lost the kickdown function.....so it may well be this throttle position sensor.So,as above,where is it?
 
Wow, didn't think I would get a response from this post 4 years later!!!

The throttle position sensor is located on the pedal assembly.

It is possible to get set up wrong as the alignment is variable. It has a splined shaft very similar to a windscreen wiper shaft.

It is fiddly to do. You need at least 3 arms and be able to bend in half.

With regard to the kickdown problem that will more likely be a cable adjustment problem or gearbox, sounds silly but don't rule out a mat riding up under the accelerator and restricting travel.

regards
Carl
 
thanks mate ,have phoned around numerous bosch agents and diesel specialists seams they don't make this sensor any more so i decided to live with it once again thanks for the reply
 
from the description on the 1st post...it seems my disco is doing similar thing now.....it's a 97' 300tdi auto with EDC by the way.....

Symptoms (1):

- acceleration (foot down on loud pedal): fine
- deceleration (foot away on loud pedal) : fine
- cruising (foot on loud pedal lightly) : engine chutters, check engine light comes up...but as soon as pedal is pressed down again....runs fine

Symptoms (2):

- On 'park' or 'neutral', engine revs to 2000 by itself occasionally without the loud pedal being depressed. It will rev at 2000 for a while, and goes back down to 1500, then back up to 2000. Sometimes, it even goes up to 3000 or 3500.
- it happens whenever she likes.....much like my wife's mood swing....
- switch engine off...let it cool down a little...and it's back to normal again........

Can anyone tell what's happening here????
 
I had the very same problems with my vehicle found second hand sensor for £50 which sorted the issues striaght away
 
Instead of replacing the throttle position sensor, I replaced the electronic injection pump to the mechanical one....effectively getting rid of the ECU/EDC system...and the disco drives so much better now...with a tweeked pump anorl...!!!
 
kingsonlim said:
Instead of replacing the throttle position sensor, I replaced the electronic injection pump to the mechanical one....effectively getting rid of the ECU/EDC system...and the disco drives so much better now...with a tweeked pump anorl...!!!
Click to expand...

I have exactly the same problem, but since having the air flow meter replaced last year (expensive £270+), I don't get the 'Check Engine'.

Is changing the throttle potentiometer difficult?

http://www.johncraddockltd.co.uk/products/stc4389_throttle_potentiometer_dies__pump_300tdi.php

I have decided that jumping from a Series 3 to an automatic '96 Disco was a mixed blessing. What I do know is, my next vehicle will not be fly-by-wire, probably a 300Tdi 90. Question is, how difficult (read as 'expensive') would it be to change to a mechanical set-up, as suggested here?

Any help appreciated.

Cheers,

Chris.
 
Last edited:
I've had a TPS problem with my 300tdi EDC 98 Auto for 2 years now. And have finally fixed it.
Symptoms: Check engine light comes on and revs to idle when driving at low throttle settings. Makes for jerky progress sometimes.
After much reading on here and RAVE, thinking, testing and trying to get the TPS off to clean it to no avail, I've finally found a solution without spending a penny or breaking my arms to get them to bend in the right place to hold the tools to remove the TPS from the top of the pedal.

I tested the resistance in the TPS at connector C195 and found the readings to be similar to the others that have reported, with a smooth progression through the range on pins 3-4, and a 10k resistance then open circuit on pins 1-2. Looking at the circuit diagrams in RAVE I found the the TPS, Bosch part no 0205001021 to contain 2 components; a potentiometer on 3-4 to sense the pedal position and a switch on 1-2 to report when the pedal is in the idle position.
It's the switch on 1-2 that causes the problem. It should be on or off, but shows a resistance, then goes off. So, when you take that switch out of the equation, the fault goes away. You do this by cutting the White/grey wire on the ECU side of connector C195, (found by the fuel filter).
This diagnosis is supported by evidence from others that cleaning the internals of the TPS with contact cleaner helped significantly with the problem.
I can only assume the switch is a failsafe device to make the system go to idle in event of the potentiometer sticking in a high setting with the pedal in the off position. Because the switch has gone faulty it comes on slightly before it should and overrides the potentiometer signal. I know how to deal with a throttle stick eventuality so won't bother making a repair, but you could insert a microswitch on the bowden cable relay arm for the kick-down that closes at pedal idle position.
 
i think youll find youve just "Tweaked" Your Pump Timing Too Far Advanced,The ECU will See The Timing Out of Range and Put on The Check Engine Light as You Push the Acelertator and go Out Again When You Release it, Just Undo The Plate and the 3 Bolts a Little and Knock it Back Just a Tad,, Tighten it all Back Up Refit The plate and it will be Fine
 
kingsonlim said:
Instead of replacing the throttle position sensor, I replaced the electronic injection pump to the mechanical one....effectively getting rid of the ECU/EDC system...and the disco drives so much better now...with a tweeked pump anorl...!!!
Click to expand...
I did exactly the same --- so much better with the mechanical pump
 
TuppyTrucker said:
I've had a TPS problem with my 300tdi EDC 98 Auto for 2 years now. And have finally fixed it.
Symptoms: Check engine light comes on and revs to idle when driving at low throttle settings. Makes for jerky progress sometimes.
After much reading on here and RAVE, thinking, testing and trying to get the TPS off to clean it to no avail, I've finally found a solution without spending a penny or breaking my arms to get them to bend in the right place to hold the tools to remove the TPS from the top of the pedal.

I tested the resistance in the TPS at connector C195 and found the readings to be similar to the others that have reported, with a smooth progression through the range on pins 3-4, and a 10k resistance then open circuit on pins 1-2. Looking at the circuit diagrams in RAVE I found the the TPS, Bosch part no 0205001021 to contain 2 components; a potentiometer on 3-4 to sense the pedal position and a switch on 1-2 to report when the pedal is in the idle position.
It's the switch on 1-2 that causes the problem. It should be on or off, but shows a resistance, then goes off. So, when you take that switch out of the equation, the fault goes away. You do this by cutting the White/grey wire on the ECU side of connector C195, (found by the fuel filter).
This diagnosis is supported by evidence from others that cleaning the internals of the TPS with contact cleaner helped significantly with the problem.
I can only assume the switch is a failsafe device to make the system go to idle in event of the potentiometer sticking in a high setting with the pedal in the off position. Because the switch has gone faulty it comes on slightly before it should and overrides the potentiometer signal. I know how to deal with a throttle stick eventuality so won't bother making a repair, but you could insert a microswitch on the bowden cable relay arm for the kick-down that closes at pedal idle position.
Click to expand...
Replaced the TPS last year with a second hand unit, but the same fault has now returned......... tried this solution but the CEL remains on when at idle, did you get the same problem or have i done something wrong?
 
Mark George,
I know little about this stuff, learning about the 300 tdi Auto the hard way :confused:. If your Check Engine Light is staying on, maybe it just needs reset with a plug into a diagnostics computer?
Looks like this is my problem too, but the switch problem is intermittent. I had it plugged into the Bosch machine at work and it showed "Throttle sensor poten/safety switch comparison not O.K." in the fault code memory. This looks to tie in with the switch making just a fraction too soon, although as I said, mines is intermittent. The potentiometer seems to run smoothly up the range (% throttle range) according to the 'Bosch', I also had it plugged into an 'Omnitec' machine which confirms everything the other machine tells me. Once I've cut the wire I will fit it with a switch to leave it on just now, but be able to switch it off if and when my problem rears it's very annoying head again. Will post once I have done it to confirm there are no problems - hopefully :p.
 
OK, job done. Cutting the grey/white wire caused the idle revs to rise, to about 1200 rpm. The "Check Engine Light" also comes on when at idle. Revving causes it to go off. As previously mentioned, I have fitted a switch to the dash with a two core going to the grey/white wire so I can have the 'low idle position switch' in circuit or out depending on whether it is behaving itself. With the switch closed the CEL is extinguished. Towing the caravan this weekend, lets hope that's it sorted :)
 
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