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Testing TPS on B230F regina

Smokey77

Smokey77

Member
Joined
Jun 9, 2024
Location
Goodyear Arizona
So I decided to test the TPS on my 1992 940, I shoved wire into the two wires on the outer edge in the back of the connector (Not the wire in the centre) and hooked up a volt meter to it. Full close reads almost 5v which already seems incorrect. Slightly open all the way to almost full reads nothing. Full open reads almost -5V. I must be doing something wrong here.

I double checked the volt meter on the battery and it works fine.
 
Didn't you test this with the Regina diagnostics and it worked ok? Usually, the center wire is the signal and the outer wires are applied voltage and ground. Or, it can be applied voltage and normally open and normally closed contacts. You need to figure out what type of TPS this is. LH2.4 uses a switch while LH3.1 is a resistive sensor for example. Not sure what Regina is.
 
Stick one meter probe on the intake ground bolt (or any other convenient ground), then measure the 3 TPS pins one at a time. The center pin should stay 0volts (it's grounded) idle/cruise/WOT. One of the other 2 pins should swing between 0volts and 5volts between idle/not-idle, and the last pin should swing 5v/0v between not-WOT/WOT.
 
bobxyz said:
Stick one meter probe on the intake ground bolt (or any other convenient ground), then measure the 3 TPS pins one at a time. The center pin should stay 0volts (it's grounded) idle/cruise/WOT. One of the other 2 pins should swing between 0volts and 5volts between idle/not-idle, and the last pin should swing 5v/0v between not-WOT/WOT.
Click to expand...
Awesome thanks!!
 
dl242gt said:
Didn't you test this with the Regina diagnostics and it worked ok? Usually, the center wire is the signal and the outer wires are applied voltage and ground. Or, it can be applied voltage and normally open and normally closed contacts. You need to figure out what type of TPS this is. LH2.4 uses a switch while LH3.1 is a resistive sensor for example. Not sure what Regina is.
Click to expand...
I only found out after that I could test with the diagnostics box. I have to find where I saw how to do it again. But all I have done is read codes and I thought I would test it to make sure before I went to try and clean it.
 
Smokey77 said:
That helps. But does this let me test if it works throughout the entirety of opening? Or just at idle? Because with a volt meter I can find dead spots.
Click to expand...

Just idle, WOT, and "neither".
It isn't a variable sensor, it's a switch. (Well, 2 switches actually)
What you (and me) have is Rex-Regina, also known as Speed Density.
It calculates throttle opening using the RPMs + MAP vacuum readings + temperatures.

The switch is basically the equivalent of 2 jumpers wires.
At idle, arm 6 closes micro switch 7 (*click*), and jumps orange and black (ground).
At mid-range (cruising) both switches are open. Should be no continuity.
At full throttle, the "hump" on cam 5 closes switch 9, which jumps Red-White and black (ground).

Backprobing with it plugged in just gets feedback from the 2 ECUs that are both looking for a ground.
Better to test the switch directly with it unplugged, use the Mode 2 diags, or unplug at the ECUs and check for appropriate continuity from there to the switch, to also rule out broken wires.


TPS.jpg
 
MasterBlaster said:
Just idle, WOT, and "neither".
It isn't a variable sensor, it's a switch. (Well, 2 switches actually)
What you (and me) have is Rex-Regina, also known as Speed Density.
It calculates throttle opening using the RPMs + MAP vacuum readings + temperatures.

The switch is basically the equivalent of 2 jumpers wires.
At idle, arm 6 closes micro switch 7 (*click*), and jumps orange and black (ground).
At mid-range (cruising) both switches are open. Should be no continuity.
At full throttle, the "hump" on cam 5 closes switch 9, which jumps Red-White and black (ground).

Backprobing with it plugged in just gets feedback from the 2 ECUs that are both looking for a ground.
Better to test the switch directly with it unplugged, use the Mode 2 diags, or unplug at the ECUs and check for appropriate continuity from there to the switch, to also rule out broken wires.


View attachment 27493
Click to expand...
Oh I see
 
Just read through your thread of it running rich. Do you have any exhaust leaks before the cat? Also when you say you did an ignition system refurb what did you install? Cap, rotor, plugs, and wires? After dealing with my Regina 740 which I thought had a good cap and rotor I would definitely look into that. You might also want to check your ohm rating for your coolant temp sensor if you know how to do that. I can send you some Regina manuals I acquired from some other members on here
 
chronicrhythm said:
Just read through your thread of it running rich. Do you have any exhaust leaks before the cat? Also when you say you did an ignition system refurb what did you install? Cap, rotor, plugs, and wires? After dealing with my Regina 740 which I thought had a good cap and rotor I would definitely look into that. You might also want to check your ohm rating for your coolant temp sensor if you know how to do that. I can send you some Regina manuals I acquired from some other members on here
Click to expand...
No exhaust leaks before the cat. Cap, rotor and wires were done before I owned the car, plugs were done while I owned the car, but it is all oem stuff, not aftermarket like NGK so already I want to redo the wires. But with how it runs it doesn't seem like an ignition problem, usually from my experience ignition is much more noticeable when it fails. I can always double check it still since I really don't know when it was actually done.
 
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