Series II RB25 TPS voltage

[maximajim]

Hello,

I'm trying to setup a Q45 TB with my SII RB25. I know in most Nissan the TPS will read 0.5v at idle. however my q45 TPS and r33 TPS is showing ~5v at idle. Is this normal? I am getting code 43 which is TPS system. I have verified the wiring is correct. Are my voltages normal?

[Steve]

between 0.4 and 0.6V indicates throttle shut. I find mine idles best at around 0.6. Under 0.4 will indicate a fault with TPS, perhaps the 5V is doing the same thing.

[maximajim]

Not good, another person on a US forum has the same problem with their SII. We both have ~5v at idle. How can this be?

[jager]

ARE YOU TALKING BOUT USING THE INFINITY

AIR FLOW METER ON A R33

WHATS TB AND TPS STAND 4

k ill forgot caps was on still trying to learn

this stuff am looking at doin the same thing if you talking

bout what i am keen to know more

[maximajim]

Hi there,

I'm trying to use the Infiniti q45 TB- Throttle Body, TPS- Throttle position sensor.

[jager]

what size are they in mm if ya know

[KamikazeR33]

all you should do is use the q45 tb and put the rb25 tps on it

[KamikazeR33]

jager - the q45 afm (air flow meter) which is what u r referring to is 80mm i think but has a higher voltage capacity

[maximajim]

all you should do is use the q45 tb and put the rb25 tps on it

It's not that simple. Here a pic so you can see the difference. http://rb25det.org/rb/tps.jpg

left SII, right Q45 (unknown year, pre 1995)

the USDM 1996 Q45 TPS looks like it wil plug into SII harness but I don't know if it will bolt to the greddy IM.

[KamikazeR33]

hmm they look kinda the same design but the turning mechanism seem to have different joins or something.

have u got a 1996 q45 tps?

my guess would to be either go this way or u will have to have the tps custom fitted

[maximajim]

Nope don't have a 96 tps, however I do have a 96 Q45 FSM. The TPS it shows is similar to the SII TPS, they may have the same P/N.

But getting back to the issue, why does my TPS read ~5V at idle with the SII tps or the Q45 TPS? When at WOT the voltage drops to ~.5V.

Seems it's reversed.

[browny]

Some guesses......(based on R32)

*you are measuring the voltage between the wrong two terminals. The supply voltage to ground measurement should be 5V. The signal to ground measurement should vary ~0.5V-4V.

*If not the above then are you sure the TPS's are wired in the same way. Because it is a potentiometer if you swap the + & - wiring it will read in reverse.

*Are you sure the TB's actually open with the same rotation eg RB30 and RB20 TB's open in different ways - one opens clockwise and the other opens anticlockwise. The TPS's are therefore designed to rotate in opposite ways and so mixing and matching can mean the output can get reversed.

As a check, get a multimeter and measure the TPS resistance (signal to gound) at idle position and at WOT position (both with the plug disconnected). What readings do you get for both TPS's?

[blind_elk]

Have you got the connectors on the right way round?

There are 2 TPSs - a Trotlle Position SWITCH, which normally tells the ECU that the throttle is closed or WOT, and a Throttle Position SENSOR, which tells the ECU where how far the throttle is open.

[cvc9216]

I'm the other guy having the same problem. Both Q45 and RB25 TPSs show ~5V at idle and ~.5 at WOT. I'm pretty sure I have it connected to the right sensor, not the switch. I measured the resistances of both. They both showed ~0.8 kOhms at idle and ~4 kOhms at WOT. When I measure the harness side of the plug (unplugged), I get 5V on one wire, ~4V on the middle wire, and 0V on the last. Is that right, can someone be so kind as to measure theirs for comparison?

Also, can anyone tell me how to check the codes on my ecu? I have an SII RB25, but it has no LED or adjustment screw on the ecu case?

[Steve]

I remeber vaguely reading that the check engine light will flash out the codes? anyone confirm this?

[cvc9216]

I've read that too, but how do I get the ecu into diagnostic mode? There is no screw on the ecu.

[browny]

On the R32's there is a diagnostic connector. This is a small brown plug located at the fuse box.

To enter the diagnostic mode you need to short two of the terminals for two seconds. This then puts the computer into check mode and it flashes the results on the ECU led and the engine check light (these are on the same circuit).

I don't know if R33 is different.

[browny]

Also, I find the diagnostic mode isn't that useful. It's good for determining whether you have left plugs off or there are short/open circuits but otherwise it doesn't tell you much.