|Setting the Mustang TPS Voltage
If you haven't already read how to do it a million times in all of the Mustang magazines then this is your chance. Here's how to check and adjust your TPS voltage. You may be asking, "What is a TPS"? Simply put its the Throttle Position Sensor. The TPS is a sensor that tells the ECM (computer) how much gas
you are giving it, which in turn lets the computer decide how much fuel and spark to give you.
What is needed?
- Phillips head screwdriver
- Two small straight pins
- Digital multimeter
How to do it
The TPS (picture 2 "B") basically bolts to the throttle body with two screws. (picture 2 "A") The holes that the screws go through on the TPS are elongated so you can twist the TPS in either direction to adjust it. To adjust the TPS all you have to do is loosen (don't take them out) both screws and move the TPS until you see the right voltage.
To hook the multimeter up you will have to pierce the green wire with a pin so you can check how much voltage is going through it. The red or positive (+) wire on your multimeter will go to the pin in the green wire.
Then you'll have to either pierce the black wire and put the negative wire from the multimeter to it, or just put the black multimeter wire to a good engine ground.
Now to check the voltage turn on your multimeter and make sure all of the wires are hooked up right. Then turn the ignition key to the on position, but don't start the car. You should be getting a reading on your multimeter. It should be .98-.99 volts. If its not, then its time to loosen the screws on the TPS and move it around until you get it right. When its at the right voltage tighten the screws and re-check it.
If you aren't too happy about piercing your TPS wires with pins then you could do what some Mustangers do. I've seen a few guys/gals buy a fuse holder and attach the two wires from the fuse holder to the green and black wires on the TPS. Then they use the fuse holder holes to check their TPS voltage.....Whatever you do, make sure you never put a fuse in that fuse holder.
If for some reason you cannot get the voltage reading right you have two options. Either buy a new TPS or take off the old one and elongate the holes a little more with a file or a dremel.
Update: We were notified by one of our viewers that the tps wires on 94-95 (and probably modular cars too) were different colors than the 87-93 cars.
On 94-95 Mustangs there are three wires just like the fox body cars but these have two grey wires (one with a white stripe) and one brown wire. After testing the wires we've figured out which ones are which. They are as follows: The first grey wire is the ground, the second grey (with white stripe) is the test wire, and the brown wire is the 5v source.
So to test a 94-95 car you would put the negative lead on your voltmeter to a good engine ground or the first grey wire. Then you would put the positive voltmeter lead to the middle grey with white stripe wire. If you need more help look at the image below
TPS wires on a 94-95
So you might be asking, "what if i have a modular car?". Well i haven't had access to a modular Mustang to be able to test the tps, but i can give you a way of testing them for yourself to figure out which wires are which.
First thing you do is put your negative lead to a good engine ground, then probe each wire (always with the ignition on, engine off) and test to see which comes up with 5v all of the time. This wire is the 5v source wire, which you don't need for this test. Then find the wire that gives you a reading of around .95-.99v with the throttle in the closed position and around 5v in the fully open position. This wire is the test wire (same as the green wire on fox body cars), and the last wire will be the ground.
So what are you waiting for? Go check your TPS voltage.
If you have any questions let us know.
Check out part 5 - Cleaning the MAF wires
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