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Can anyone tell me what sort of ohms readings I should be getting at the throttle position sensor? My meter reads 05.42 closed, and when I fully open the throttle fully, it reads 1.435. Does this make sense?
As far as I know, the way you check tps is in voltage, not ohms. There is a 5v feed to the tsp. The tsp has a resistor in it that cuts that voltage back. You test with KOEO. Measure voltage at idle, and again at WOT. Should be in the range of .70v at idle and 4.70v at WOT. It can vary some but those are acceptable numbers for an example. If it’s too high at WOT, (I don’t remember the high limit off hand), it will set a trouble code and things might get whacky. On my 94 LT1, when the tps high voltage threshold was crossed, it messed up the transmission shifting pattern. It self corrected once the tps voltage problem was fixed.
Yes, you read a voltage on the TPS “signal” wire not resistance…is it resistance or a voltage number you are quoting ??…it is a simple 3 wire potentiometer …see diagram below…remove the connector and with key ON engine OFF check for voltage on the 5 volt reference wire (GRAY)…you should see 5 volts… now plug it back in…with throttle closed (foot off the gas) you should see below 1 volt back probing the signal wire (DARK BLUE)…now push the accelerator pedal to the floor…now you should see more than 4 volts but less than 5 volts…it is a good idea to check the sensor ground (BLACK) with the engine running if you can…if not running key ON engine OFF…you should see less than .1 volts (100mv’s)
Can anyone tell me what sort of ohms readings I should be getting at the throttle position sensor? My meter reads 05.42 closed, and when I fully open the throttle fully, it reads 1.435. Does this make sense?
Thanks, that's mostly what I have found. I did find one video somewhere yesterday that dealt with ohms. Maybe the guy messed up and meant "volts" when he said "ohms"...Can't seem to find it anymore. I'll have to check again tonight...thanks.
Let's say the numbers I got above are volts...would those seem off enough to cause codes, misfiring, stalling?
Yes, you read a voltage on the TPS “signal” wire not resistance…is it resistance or a voltage number you are quoting ??…it is a simple 3 wire potentiometer …see diagram below…remove the connector and with key ON engine OFF check for voltage on the 5 volt reference wire (GRAY)…you should see 5 volts… now plug it back in…with throttle closed (foot off the gas) you should see below 1 volt back probing the signal wire (DARK BLUE)…now push the accelerator pedal to the floor…now you should see more than 4 volts but less than 5 volts…it is a good idea to check the sensor ground (BLACK) with the engine running if you can…if not running key ON engine OFF…you should see less than .1 volts (100mv’s)
Thanks! I will check again tonight. With the numbers I got above, maybe it was volts and not ohms...seeing as they are close, but not correct. Would the numbers I got (If volts) cause problems like stalling, misfiring, getting codes, etc.? I think closed it was over 1 volt, and open it was over 5 volts.
With a faulty TPS sensor you’d mainly see issues such as hesitation when accelerating, idle surging, and RPM changes…with stalling and misfires maybe a faulty crankshaft position center…now these are only guesses…I’d put test equipment on the crank sensor so I know 100% for sure…if you see those voltages you’d have TPS codes and probably a reduced engine power message
With a faulty TPS sensor you’d mainly see issues such as hesitation when accelerating, idle surging, and RPM changes…with stalling and misfires maybe a faulty crankshaft position center…now these are only guesses…I’d put test equipment on the crank sensor so I know 100% for sure…if you see those voltages you’d have TPS codes and probably a reduced engine power message
Thanks...It was late yesterday, and not even sure how I tested it. I think I was doing ohms with the TPS unplugged. I probably need to check for volts with it plugged in right? Can you tell me how I might do that? If I stick the probes in from the back of the connector, will it make contact? Hoping not to have to cut into the wires etc.
Thanks...It was late yesterday, and not even sure how I tested it. I think I was doing ohms with the TPS unplugged. I probably need to check for volts with it plugged in right? Can you tell me how I might do that? If I stick the probes in from the back of the connector, will it make contact? Hoping not to have to cut into the wires etc.
Thanks...
Like I mentioned you want to make sure you have 5 volts with the sensor unplugged on the gray wire...plugged in checking voltage you should see the voltages I mentioned...if you don't own back probes which are designed to do this testing you can use a sewing needle or buy some T pins from a craft store...you just run the wire along the wire into the connector until it stops.
Like I mentioned you want to make sure you have 5 volts with the sensor unplugged on the gray wire...plugged in checking voltage you should see the voltages I mentioned...if you don't own back probes which are designed to do this testing you can use a sewing needle or buy some T pins from a craft store...you just run the wire along the wire into the connector until it stops.
Okay, I do remember getting 5 volts, but will check again. Are "back probes" available at auto parts stores?
Okay, I do remember getting 5 volts, but will check again. Are "back probes" available at auto parts stores?
Thanks!
I’m not sure but you would have better luck at the craft store for the T pins…I’ve ordered mine from Amazon and a few other websites…pics below are back probe, T pin, and 2 “piercing” probes.
Do the back probes just provide a very pointy tip? Looked like the only difference from the probes on my multimeter, and I have a test lead set from working on guitars and amps that have very pointy tips to them...Maybe I already have them...
Do the back probes just provide a very pointy tip? Looked like the only difference from the probes on my multimeter, and I have a test lead set from working on guitars and amps that have very pointy tips to them...Maybe I already have them...
YES !!…very thin and pointy tips…DVOM leads are way too big !!
Well, in the first test...I put the black probe alligator clipped to the negative post on the battery. I put a pin in the back of the grey wire to the TPS with the socket in. I turn the ignition on (Not running). When I touch my red probe to the pin in the grey wire, I get ".500"...Does that mean half a volt?
I'll probably try the next step, but does this already determine the TPS is bad?
Also, with the connector off ,key in...I get exactly "5.00" at the grey wire...
Well, in the first test...I put the black probe alligator clipped to the negative post on the battery. I put a pin in the back of the grey wire to the TPS with the socket in. I turn the ignition on (Not running). When I touch my red probe to the pin in the grey wire, I get ".500"...Does that mean half a volt?
I'll probably try the next step, but does this already determine the TPS is bad?
Thanks...
You want to see 5 volts at the GRAY wire with it unplugged...now plug it in and check the DARK BLUE signal wire foot off gas and pedal down !!...the PCM is looking at that signal wire.
Well, in the first test...I put the black probe alligator clipped to the negative post on the battery. I put a pin in the back of the grey wire to the TPS with the socket in. I turn the ignition on (Not running). When I touch my red probe to the pin in the grey wire, I get ".500"...Does that mean half a volt?
I'll probably try the next step, but does this already determine the TPS is bad?
Okay, here are my findings...Blue wire, throttle closed, around ".600"...moving throttle open, it goes well until right around 4 volts....then the meter reads "OL", and it still has more to travel to be fully open.
Okay, here are my findings...Blue wire, throttle closed, around ".600"...moving throttle open, it goes well until right around 4 volts....then the meter reads "OL", and it still has more to travel to be fully open.
Pretty much failed all tests then? Is that right?
Throttle closed voltage is good...I said less than 1 volt is good...press the gas to the FLOOR and what is the voltage ??...you should check that ground too.
Throttle closed voltage is good...I said less than 1 volt is good...press the gas to the FLOOR and what is the voltage ??...you should check that ground too.
Okay...most stuff I saw previously, it was usually more in the .800 range, but if .600 is within specs, then I understand.
All the way open, it reads "OL"...after if hits 4v, it goes to "OL" even though it has more to open,
Okay...most stuff I saw previously, it was usually more in the .800 range, but if .600 is within specs, then I understand.
All the way open, it reads "OL"...after if hits 4v, it goes to "OL" even though it has more to open,
Thanks...
Can you tell me how I check the ground?
Thank you...
This is Service Info for a 96 for the TPS circuit…it says above 4 volts but it shouldn’t go “open circuit” at WOT…most TPS sensors I’ve looked at stay below 5 volts at WOT…it’s best to check the ground at the black wire engine running…black voltmeter lead to ground and red lead to TPS ground…less than .1 volt !!…if the car doesn’t run just key ON !!
This is Service Info for a 96 for the TPS circuit…it says above 4 volts but it shouldn’t go “open circuit” at WOT…most TPS sensors I’ve looked at stay below 5 volts at WOT…it’s best to check the ground at the black wire engine running…black voltmeter lead to ground and red lead to TPS ground…less than .1 volt !!…if the car doesn’t run just key ON !!
Okay, I tested the ground both ways...running ".027", and with just key in, "015". Seem okay?
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1996 LT$ Throttle Position Sensor
