Due to a part throttle flat spot I have suspected that my throttle position sensor was bad. I purchased a known good used one (pf01) to replace it with. I've just finished probing the wires to check to voltages with an analog meter. Here is what I found. It seems that both sensors produce the exact same results. At idle position the voltage is being read at approx. 2.5-2.75 volts. As soon as the throttle is cracked open a bit the voltage jumps up to about 4.25-4.5 volts and drops smoothly as the throttle is opened until it hits 0.5 volts. Is this normal? I used the analog meter to make sure that there were no dead spots in the sensor.

I am aware of the switch built in to the sensor that tells the computer that the throttle is closed. Is this why at idle the voltage is 2.5-2.75 and then jumps to the higher value stated above?

All information appreciated. Thanks in advance for the responses.

Tommy

 

There is NO switch in the 2wd throttle pots.
They should read around 4.5 at idle dropping to around 0.5 at fully open.
At no time should it read 2.5-2.75 at idle.
This points to them being shagged, it is normally just around or above idle that suffers, I have some piccies of the tps cut open if you want, you will be able to see what's what, and the lack of switch.
A bodge that has sometimes been used on other tps's is to use a carbon stick to recarbon the track only last very little time I'm afraid.
tabetha

 

If I use a digital meter I get 4.75 at idle. When I open the throttle a little it goes from 4.75 to the 4.3x range without making any readings between those numbers. I can't get either sensor to show an 4.4x,4.5x or 4.6x number on the volt meter. Can I assume that their both burnt in the same place???

 

2wd TPS should read 5 volt (or very close to 5 volt) with throttle closed.
When it is opened just a little bit it should jump to 4.5 to 4.7 volts and then slowly decrease when the throttle is opened further.
As said: at no time should it give around 2.5 volt when the throttle is closed.
Also measure the 5 volt supply. Is it always 5 volt (or very close to 5 volt)?

 

They will never be 5 volt unless your metre is out, 5 volt is the refference feed, it is not closed even when you think it is, as it has a internal stop, that the mechanism rests on, this is set so that it always detects some throttle angle.
They do usually go a bit iffy just around or above idle as this part is the most used, mine did, and it caused a mystery hesistation, till we put the scope on it, then changed it to a universal one, been perfect since.
It is unlikely that you will get all the readings as it is so sensitive, I haev had one on the bench testing for duff patches, and although this one worked perfect it was nigh on impossible to get certain range readings.
A 4wd one will fit, with reversing the outer wires, it won't be perfect though, but certainly better than a duff one.
Any that has the same resistance/range as std will fit, as it has a std "D" shape shaft, my one is from a rover I think, I just grabbed it as it was already there, but I run a different ecu, so it can cope with this, you will need one correct.
tabetha
tabetha

 

A 4wd one will fit, with reversing the outer wires, it won't be perfect though, but certainly better than a duff one.
Are you sure? That would need a change in the ecu.

 

I think I got it wrong about swapping the outer two wires, though you can defo use the 4wd one, like I said won't be perfect as idle strategy is different.
Best ask stu(MSD) as he is sure to know.
tabetha

 

I'me sure the 2wd has 5 volt (or very close to 5V) on the TPS when idling.
See: http://www.siipicossu.com/manuaaleja...sis%20Info.pdf
and: http://www.siipicossu.com/manuaaleja...Sierra%20D.pdf

 

Thankyou Oldford for those PDF Files, they have explained to me how to test my electric. I will have a go tomorrow and see if I can work out why my ISCV isnt working