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Discussion Starter · #1 ·
hi,
I live in N Wales and have owned a X trail for the past 3 years with no problems. I fix aircraft for a living but cannot get my head around this problem if anyone can help i would be grateful.

The model I own is a 2002 2.2TD Sport used for everday running around and for transporting my daughters horse (in a trailer) to local shows. It is currently off the road with a fault code of P0120 Throttle position sensor Nissan want £450 for a new one and will not accept a return if it does not cure the fault. The car went into limp mode twice previously but when the ignition was switched off and then back on all went back to normal, now it will not clear. Does anyone know if there is anything else that may cause this problem and will. I have removed the assembly from the car and had voltage checks done on the two potentiometers and these appear to be normal(.5v - 5v dependant on throttle position) on the switch there is a high resistance of 200-350 ohms when the throttle is in the idle position and goes open circuit once the throttle is depressed is this normal. The assembly has an 8 pin connector. Also I can get hold of a secondhand pedal assembly but it is off a 2 litre petrol version is this compatible. :headbang:

Not a bad first effort at trying to get some help.

thanks in advance

Billy B
 
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Discussion Starter · #3 ·
Ebonyuk said:
hi,
It is currently off the road with a fault code of P0120. Nissan want £450 for a new one and will not accept a return if it does not cure the fault.
........ on the switch there is a high resistance of 200-350 ohms when the throttle is in the idle position.....
Billy B
Hi from another newbie (with new bees this year).
Hope you've solved your problem, and maybe you could help me. I've got a 2003 SVE TD and could check my potentiometers resistance range if I can do it without removing the assembly.

I've downloaded "X-trail manual-T30" torrent and think the engine control system YD section applies to my car. It certainly leads me there after entering my VIN.
It shows specs (with ignition on & engine stopped) of:
sensor 1 (pin6) ECM terminal B15 W) released 0.8V-1.3V fully pressed >3.5V.
sensor 2 (pin 3) ECM terminal B16 G) released 0.3V-1.8V fully pressed >3.0V.
accelerator pedal released switch (at ECM terminal D14, G/Y wire) released approx 0V, slightly pressed Battery voltage (11-14V).
200-300 ohms seems a little high for a switch, I would try checking the voltage goes to near 0V and the switch or wiring isn't intermittent - try tapping around it, its connector and the ECM connector to check this.
Measure the sensor voltages at the ECM end to check the wiring.

Could you check the dashboard code readout procedure below for me. I found it suggested for x-trail at
http://www.nissanforums.com/x-trail/992 ... trail.html
I've tried it but my MIL just stayed on permanently.
Now don't know if this means my ECM is faulty or that this procedure isn't good for the UK X-trail TD. A number of garage diagnostic systems will do X-trails but not the 2.2 diesel model.
............................................................................
1) Sit your butt in the driver's seat.
2) Turn the ignition key to the ON position and wait three seconds. (Do not start the car.)
3) Fully depress and release the accelerator pedal five times in less than five seconds. (If you've got bad ankles, give up now and drive the car to the dealer.)
4) Wait exactly seven seconds. Fully depress the accelerator pedal and hold it down for about ten seconds until the MIL light begins flashing.
5) Release the accelerator pedal and start counting flashes to obtain the four-digit trouble code. Long flashes (0.6 seconds) indicate the first digit of the code; count the blinks one through nine and write down the first digit. (Ten blinks indicates a zero.) The next three digits follow in turn in the same fashion except with faster blinks (0.3 second) and a 1.0-second pause between digits.

The ECM code repeats intself until you turn the ignition key to the OFF position, at which point the ECM resets itself to standard get-in-and-drive-the-car mode.
You can look up the trouble codes in the ESM/FSM; there's a bunch of them. In the ESM, refer to page EC-639. Additionally, if you get four blinks of ten (0000), the ECM is indicating no malfunction.
You can clear the code (and the annoying MIL) by holding down the accelerator pedal for more than 10 seconds while in Diagnostic Test Mode II. When you release the pedal, the ECM erases the trouble code(s).
...........................................................

It would be good to know which X-Trails the procedure works on. Can someone oblige?
 
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Discussion Starter · #4 ·
Hi,

Iborrowde a fault reader from a friend an OBDII, this gave me the fault code. Ito have a manual for the car and following its instructions took the readings from the pins on the connector. My car has an 8 pin connector but I believe yours may have a 6 pin. I removed the pedal assembly from the car as it was easier it is only held on with two nuts and takes about 10 mins to remove then I did the readings on a bench. You will need a variable voltage supply and multimeter to take the readings. Again here I had some help from some guys
i work with in using their equipment and found the high resistance on the pins for the idle switch. I tried everywhere to get a secondhand assembly with no luck(no 8 pin connector ones but plenty of 6 pin) I had to bite the bullet and get a new one, £426, I pfitted it and it cured the problem. Nissan said to just plug it in and drive away. This worked for me, I plugged the fault reader in in case of any readings maybe stored in the ECM but there wasn't. In fact since changing the assembly the car has been driving like a dream. Iam now going to buy one of these fault readers for myself they cost about £60 -70 on the internet it will be cheaper than going to a garage everytime and will work for most makes of car.

Billy B (Ebonyuk)
 

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Hi, I own an Xtrail 2002 2.2 TD bought almost 3 years ago, after 1st year had the same issue, got so bad it was going into emergency mode approx every 10 miles, mostly noticed when simply cruising along, under hard acceleration i.e. driving a bit quickly the car didn't seem to have issues.

I also got a quote then after picking myself off the floor decided there must be a home remidy to sort.

Deicded the issue lies somewhere between the sensor on the pedal and the connector under the bonnet, sprayed the connector with loads of WD40, and drowned the pedal, this cured the issue for about 4-5 months, whereby it returned, I did have it into a dealer to check and by the time it got to them it was behaving, but the recorded a .1 drop in volts or amps on the line at full depression on the pedal so confirmed it was more than likely the censor causing the issue.

For all you out there not really understanding the inards, the swith on the pedal is effectively the same as the volume control on the really old tape players, a wheel with different levels of resistance as the contact moves over the whole surface, about .1p in cost!!!

Anyhow i figure the issue is wear an tear or more likely dirt buildup on the contacts that in it's most common position (cruising along) it creates a low contact that causes the engine management to detect a problem and go into safety mode, hence the reason the WD40 clears the issue, basically give it a good clean without taking it apart.

If i keep having the trouble I intend to locate a used one and take it apart and try a home fix, I'll post a vid on you tube of how if i do it, as you can't run the vehicle without one I can't afford to screw mine up without having a replacement and I am not buying one for £450 or a second hand one for £250 when it's a cheap piece of technology being sold at a massive fortune.

If anyone out there ends up buying themselves a new one, insist on keeping your old one and I'll give you £30 for it, email my junk account [email protected] if you have one, note date of this posting is 02-11-2011 I will reply to it if I end up buying one from someone.

All the best
 

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Mario-1973 said:
Hi, I own an Xtrail 2002 2.2 TD bought almost 3 years ago, after 1st year had the same issue, got so bad it was going into emergency mode approx every 10 miles, mostly noticed when simply cruising along, under hard acceleration i.e. driving a bit quickly the car didn't seem to have issues.

I also got a quote then after picking myself off the floor decided there must be a home remidy to sort.

Deicded the issue lies somewhere between the sensor on the pedal and the connector under the bonnet, sprayed the connector with loads of WD40, and drowned the pedal, this cured the issue for about 4-5 months, whereby it returned, I did have it into a dealer to check and by the time it got to them it was behaving, but the recorded a .1 drop in volts or amps on the line at full depression on the pedal so confirmed it was more than likely the censor causing the issue.

For all you out there not really understanding the inards, the swith on the pedal is effectively the same as the volume control on the really old tape players, a wheel with different levels of resistance as the contact moves over the whole surface, about .1p in cost!!!

Anyhow i figure the issue is wear an tear or more likely dirt buildup on the contacts that in it's most common position (cruising along) it creates a low contact that causes the engine management to detect a problem and go into safety mode, hence the reason the WD40 clears the issue, basically give it a good clean without taking it apart.

If i keep having the trouble I intend to locate a used one and take it apart and try a home fix, I'll post a vid on you tube of how if i do it, as you can't run the vehicle without one I can't afford to screw mine up without having a replacement and I am not buying one for £450 or a second hand one for £250 when it's a cheap piece of technology being sold at a massive fortune.

If anyone out there ends up buying themselves a new one, insist on keeping your old one and I'll give you £30 for it, email my junk account [email protected] if you have one, note date of this posting is 02-11-2011 I will reply to it if I end up buying one from someone.

All the best
If it's a potentiometer, why not try switch cleaner, rather than WD40?
 

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I'm not familiar with the X-TRail one but on other "Throttle-by-wire" vehicles, they are usually two potentiometers "back-to-back" As the throttle is pressed, one will go from a low resistance to a high resistance, and the other from high to low. The ECU will look at both resistance readings and check them against each other. If they don't match, it will throw up a fault code. Given the safety implications of a throttle-by-wire components failing, they probably wouldn't dare rely on just one potentiometer!
 
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