Power Steering Pressure Sensor Testing (applies to all psi sensors) - Toyota (P0550)
ฝัง
- เผยแพร่เมื่อ 4 ส.ค. 2024
- This video can be used to support chapter 8 in my book and the procedures shown can be applied to all types of pressure sensors. (MAP, power steering, transmission, BARO, fuel pressure etc)
In this video we’re following up on a previous video, in which we found a poor engine ground. This time, we’re using some simple voltage tests on a three-wire pressure sensor to verify wiring and signal circuit integrity. No ohmmeter, wiring diagram or flow charts required!
Engine Performance Diagnostics chapter 8
Symptoms
- check engine light (P0550)
Fix
- replace power steering pressure sensor
Tests shown
- using scan data
- distinguishing between a current (hard fault) and history fault (soft fault)
- identifying the type of sensor based on the number of wires used
- how to understand circuit design based on the type of sensor
- using a scope to test a 5V sensor for supply, signal and ground
- how to verify your scope connection to a circuit
- verifying signal circuit integrity with signal voltage fixed low
Tools used
- scan tool
- lab scope
Playlist
- (Chapter 8) Pressure Sensor Testing, MAP, BARO, DPFE, fuel tank and rail pressure sensors
• (Chapter 8) Pressure S...
Related videos
- Poor running, flashing CEL, no codes (bad computer ground) - Toyota
• Poor running, flashing...
- How to test TPS wiring with a scan tool (any car)
• How to test TPS wiring...
- How to test throttle position sensor wiring with a resistor (any car)
• How to test throttle p...
- How to troubleshoot an EVAP Pressure Sensor problem P0452 - GM
• Pressure Sensor or Pot...
- No Start from a shorted MAP sensor (Honda, Acura)
• No Start from a shorte...
For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium www.scannerdanner.com/join-sc... There is a 14 day free trial.
On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!
Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC. - ยานยนต์และพาหนะ
Why would anyone give this a thumbs down? This channel is one of the best if not thee best automotive diagnostic help videos on TH-cam. I have learned so much new stuff. Thanks Mr. Danner for making this subject matter easier to understand.
Thanks so much Gary!
Paul you are a Ausome teacher.I watch all your videos
I wish i would have had teachers like you when i was in school
Thanks for the excellent videos you put out
Paul I just want to say thank you for all you do. I am a marine technician and this video helped me track down a faulty MAP sensor on a late model Mercruiser 5.0 MPI . Would not set a trouble code but when I went through the diagnostic process found no reading from sensor.
with every video I watch on his channel he puts together the head-breaker of my knowledge. it is admirable the way he teaches, thank you very much paul.
Thank you my friend
Watching this is better than any prime time television show.
Hey Paul your are sharing ur wisdom without any hesitation at all.I hope becoz of that merit you gonna make good income in return for your work.also I wish More students will come to learn from u.
poetry in motion! Thank you again Paul.
Today i passed the A8 ASE test your book and youtube vids helped me alot! Thank you paul keep up the good work!
Another simple easy to understand video!
I do have a digital oscilloscope, but, like most DIY mechanics, I can't afford a labscope. Therefore this kind of "manual" workup is much more applicable to how many of us would do this at home. Thanks!
Your videos are great! I hope that some day I will be as good at troubleshooting as you are!
Thank you Paul your video really help me to pass ASE A8
that's awesome man congrats! The L1 is next!
Great video Paul.
@dreamer2355 no problem it would have been nice to have a new power steering pressure switch to show what a good 1 look like. car is gone now though. thanks for your comment!
Always an amazing video!
Thanks for posting the fix!
SUBSTANTIAL Sir ScannerDanner
thank you , take care
Sir ScannerDanner
From Nick Ayivor from London England UK 🇬🇧
Another great video! Thanks for the info.
great question. you could go by the trouble code. if it had a circuit low code and now has a circuit high code then you know the PCM is responding properly.
Thanks a Lot Amigo For Shareing Your Knowledge & Time, May God Bless You...
My pleasure my friend, thank you
Awesome job.
Thanks for the video.
Great Video as always.
Another great video...............thanks
Very nice information sir👌🏻
I am testing an air condition high pressure sensor and it should be a digital square wave and I am getting an AC sine wave. I believe it is a bad pressure sensor and the internal circuitry in the sensor is damaged, but not sure why I would get an AC sine wave. The test I am doing is exactly what I have learned from you scannerdanner. Thanks for the valuable information. Keep them coming!!!
If it is a low amplitude sign wave it may actually be interference from the lighting in the garage and the reason you're seeing it is from an open circuit. Is it by chance a 60 hz signal?
ScannerDanner Premium I see what you are thinking, but the car is tested outside. Wife has car today, but I will do a circuit integrity test when she gets home. The sine wave is actually like a variable reluctance cam signal like the one on the right of this image. It still could be interference just kind of strange. I was using the Uscope and will get specifics such as time base and frequency etc.. Ill let you know what I find out. Its a 2003 VW Jetta. Great problem for this kind of troubleshooting... Thanks!
@manicmechanic22 it was the signal circuit and the 5 volts that you see comes from an internal resistor that is used for diagnostic purposes. most people do not know it's there or how to use it
Paul you are awesome, you know that already, but let me say that again ))). As always great job, excellent explanation. Love your vids. cheers from Kyrgyzstan, we are watching you. Hope you will never leave us, and will continue share repair cases to us. Last thing i want to say, are there any hybrid vehicles you worked on ? looking forward for vids with hybrid cars )) Thanx a lot !!!!
thank you my friend! and I am here to stay :-)
just great thanks man
good video, similar to testing potentiometer.
Well done. Question: seems to be quite common for test procedures from OEM's to be disregarded for better and faster techniques , any idea why the OEM's constantly refer to test flow charts that make no sense. The best one I like is (do you see system voltage , if yes , change part) . :)
thanks!
Is it normal for the voltage to increase that slowly when you unplugged the sensor? I was expecting a more vertical graph section I couldn't read the scope very well, how many milliseconds was that from the low voltage plugged in to the 5v unplugged?
Love your videos. I learn something every time. Appreciate you taking the time to do this.
thanks for this...
I have a Hyundai Elantra 2003, knock sensor is bad zero resistance but before plugging a new one I tested the voltage (ign on) arriving to the sensor`s plug (sensor disconnected). There is 2 wires, white=ground/brown-signal, and the voltage arriving there is 2.27v. Now, I searched everywhere even the diagrams and IDK what voltage should arrive to this sensor, all other cars models/manufacturers says 5v so I believe mine should be the same. I will do the voltage test directly in the ECM pin but if it shows 2.27v again how can I assure if it`s ok or I have a bad ECM? do you have this knock sensor voltage information for this car?
Great channel BTW, subscribed!
@ScannerDanner Another great one.
Good test
Sir how can i explain gear shaft solenoid 12345 gear and torque converter cluch and so.becouse I have not all data and scaner .You have idia for explanation?
GOOD VIDEO .!!!!!!
You say you were t-pinned into the signal wire? So where did the 5V come fromwhen you unplugged?, or were you testing the 5V ref circuit here?
Awsome videos by the way, I'm going over to your site now.
Question, a two wire pressure switch would be a on/off switch most likely connected to ground?
My car got the same issue, P0550 - Power steering pressure sensor signal fault. Problem. State: Intermittent. I have a Citroen C4 petrol 1.6 16v, just changed the coils and spark plugs and the engine dies whenever I stop at a red light or moving slowly. I get check engine and anti pollution faulty error. Could this be the reason why it does that? Thanks in advance.
thanks for this informative video,
in the last minute of the video you have mentioned that there is an internal resistor and it needn't to disconnect the sensor and computer to diagnose if there is a short or open in the signal wiring, what do you mean by internal resistor?
This will help! th-cam.com/video/CkgrMasd57s/w-d-xo.htmlsi=fBKxqtkx__etJ7AE
Wow, you're video was so informative and easy to understand! I'm wondering if I could do the same test using a DVOM on my '07 Honda Pilot? The dealer told me I had a seeping power steering pump, so when it started whining I topped it off, assumed it was that and eventually replaced it along with the o-rings-without confirming that was the cause...I know my bad. Soon after it started whining again, on and off. The fluid level is within parameters not bubbling but swirling (which I've never seen a car do before) on and off, and today it appears to have overflowed from the top of the reservoir. I did read that someone replaced the reservoir, which is known to clog on this particular yr, make and model and that eliminated the whining problem, after having replaced the o-rings and pump. I suspect I may have multiple problems, the switch being one of them but would like to pinpoint the problem prior to replacing anything else.
What you're describing would not be related the the pressure sensor at all. I'm sorry but I can't help further other than to say you have a hydraulic system issue, not electrical. Steering rack, pump, restrictions etc etc
could be power too (Section 2 switch inputs, pull-up and pull-down circuit designs)
I am using the reply button, but sometimes it is with my phone.
Not sure why it shows up that way. Thanks, I'll check into it
how i wish i have the same knowledge just like this guy. ohh, and have all his tools though. 😂😂
I DIDNT GET IT
WHy did the VOltage Rise .. where does this voltage come from ?
Is the sensor wire connected to the 5V reference wire ?
If the wire already has 5V why do we need a reference wire with 5V ?
hey Danner, i though you were annoying at first but you are a hell of guy... i am addicted to your damn videos now...
🤣 I've had the same felling of others in my life and they end up being my go to people for information. Thanks man, really appreciate it.
Nice
Hi Paul which wire did you back probe to check if the signal wire was shorted to ground was it the power wire or the signal wire when you disconnected the plug thanks
signal from computer
?..
@turbobuick33 idle speed control also AC compressor clutch cut out
If we disconnect the connector and do not get 5 volts on the signal wire, would it be safe/effective to use a power probe hook, on the voltage reference mode to send a small voltage down the signal wire to test its integrity instead of using a resistor?
Yes. I wanted to buy the hook for this very reason. Remember though on some designs there is 5v on the signal wire already with it unplugged (bias voltage)
U can get a LED test light that will give u a red light for power and a green light for ground,dnt really know if using it in these situations would be advisable
I'm missing something here. Unplugging the connector surely leaves the signal wire having no volts back to the ECU, so how did it suddenly get volts along it. You never bridged the 5v ref wire to it, so would you mind explaining in words what happened there?
Bias voltage from ecu.
The computer sends 5v to that sensor, so by unplugging it and verifying that the voltage is there- it rules out the wire all the way back to the computer. think of it like this- just because you dont plug something into a wall socket- doesnt mean that 120 volts isnt on that curcuit. hope that helps.
I guess we better buy the book bro...
Why not leave the lead on the sensor signal on the sensor side, and check continuity to ground to check short your ground on signal?
@fakeBULL sorry I let the car go apparently the blue temperature light is a cold engine light. not 100 percent sure on that just going by other comments
Good video as always now fix my car lol
When you disconnect the sensor-harness plug and you have your lead on the harness side signal wire, how does the signal wire from the harness side get 5v instead of 0v? I must be missing something because I'm thinking that when you unplug the connection, it becomes an open circuit to all 3 wires, which would mean 0v at the signal wire on harness side.
There is a bias voltage on some of these signal circuits
@@ScannerDanner I watched one of your videos which explained bias voltage! Thanks!
@Username64870 thanks man.
Mr. Scanner. Could a bad pressure sensor cause a car to shut down when you're turning? My sister-in-law's 2005 F150 V8 is turning off when she turns it's left or right but it's intermittent, all the lights go on and the radio stays on but has a blank screen.
+vinnymac01ss your thinking is on the right track. something is shutting that system down and it seems by your description that it also affects the radio?
that's weird. any fault codes in memory? I don't think a psi sensor would be related to turns, but there may be a power steering psi sensor that could share this 5v ref. I'm not sure without looking at a diagram.
+ScannerDanner So I did look up a wiring diagram and found out that this sensor is spliced in with another sensor that since you're being the fuel rail pressure transducer sensor could that be a possible reason of the car shutting down maybe it has a short to ground? I also look at the wiring diagram for the radio that is it's own wiring so I'm just assuming that's happening because the cars just shutting down.
thanks man! don't forget to check your spam folder for an email sent to you after your purchase. Also look for one from me too for a little helpful hints on usage.
the signal wire
do you think its possible to check signal wire with volt meter
Of course, especially on this type of sensor as it doesn't have very fast changing signals
Ok...finally got over my weekend ps blues and frustrations to actually watch more of this very detailed video. Barring my forementioned complaints/ps symptoms...
1) is it possible for a ps sensor to have intermittent problems, perhaps a partially striped wire grounding out ?
2) you keep talking about the computer code. Yet the sensor tells the computer to regulate the rpm's. Does this sensor trip the idiot "Check Engine" dashboard light or not? And if not, how does the tech know to go looking for a fault code? Also,
Don't have a scope, can this "voltage" check be done with a DC meter ?
you are having intermittent tight steering complaints right? Was the power steering pump changed? Was the steering rack changed? What are you working on? (year, make, model, engine)
@@ScannerDanner
2005 Toy Sienna
Nothing has been serviced
Three recorded incidents:
steering locked up (almost IMPOSSIBLE to turn) twice on first left turn on cold morning (S. Oregon so it was only ~30°) following three right turns around block at idle speed.
The third time was again at cold temp at night after sitting for 3 hrs but it was a right turn this time. Symptoms not as bad but felt like switching from power to manual.
Was thinking if it happened again I should switch it to neutral a raise the rpms then put it back in drive, maybe just downshift? But the incident happened so fast and the power returned within seconds
No belt squeaks
Belt still looks good, no cracks, tight within ~1/2 play.
No steering wheel squeaks
No dashboard codes
No PS leaks
No contamination of fluid
No metal flakes in fluid
No recent service work.
Used Seafoam Trans/PS flush against better judgement. Typically don't like additives but used it on account of making sure any contaminants were worked out of system. MSDS says its just alcohol anyway. Proceeded to run engine (start and shut off) several times, working fresh dextron (ie. Toy PS "fluid") through entire system with engine jacked up. both running and off from lock to lock several times. Used about a gallon of PS by the time it was all said and done. No contaminants, congealed droplets or heterogenous mixing of disimilar fluids observed in old fluid.
checked upper U-joint on intermediate shaft. looked clean. wiped down anyway and used spray white lithium. Could not see U-joint on bottom. Will have to jack up engine again to spray grease it too. Will replace if rusty or corroded, doubt that is it though.
Drove it a few miles. But it is an "intermittent" gremlin. Guess I will have to wait until it is extremely cold to test or catastrophic incident occurs? Hmmm. Only thing else I can do as an end user is replace the belt. After watching more of the video it occured, what would happen if the sensor was intermittently bad? And if it was, would it trip a dashboard code and if not would the fault code still be recorded in the system? Cant think of anyrhing else and no one can suggest anything short of throwing parts at it. Thx for reading Dan.
Hi Paul, great job, thanks o lot.
I wonder, if making a jump 5v ref to the signal wire is always safe. What about, when the signal wire is shorted to ground by wires, not by a sensor? Isn't it like we'd do a 5v ref shorted to ground and then...
Greatings from Poland
almost identical
What ARE THE BASICS I NEED to program general motors cars .
You can use a J2534 programmer for most GM's (I think). I don't do much programming.
THANK YOU MISTER DANNER FOR YOUR RESPONSE .
What is the purpose of the power steering pressure sensor?
just another thing to cause us headacks
Yeah I really don't understand why the signal wire would jump to 5 volts, along with the reference signal...
Replied above
could this same test be done with a tps for example ?
Absolutely, every step
@@ScannerDanner if there was no 5v in the ref. wire, would a good test be checking the continuity between the 5v ref. wire and the pcm?
@@adreesrehman5509 I have some videos on these tests th-cam.com/video/hJQ6qnhTgdg/w-d-xo.html and th-cam.com/video/ecz93B5SRsQ/w-d-xo.html
@@ScannerDanner I've watched them before, think I need to rewatch lol, or just get your book an join premium
Ok I did some critical thinking about the circuitry. And the only scenario that I could think of that would leave the signal wire with 5V unplugged is as follows. If you hop over to your video that compares potentiometers and thermistor circuit designs, you can see how a thermistor circuit has a resistor built into the 5V send/signal wire, and essentially uses the voltage drop that occurs, between the integrated resistor and the thermistor, from either extremely low resistance in the thermistor (nearly a short), or lack thereof from high resistance as the signal. I am guessing the same technique is used on some types of 3 wire potentiometers. Although, then I wouldn't see the reason for a 5V ref, if your going to measure the signal of a potentiometer, like a thermistor. F*** I don't know....
I have some lectures on this on my premium channel. Your close, there is an internal resistor (very high ohm) that connects from the 5v ref to the signal wire and can only be "seen" when there is an open circuit. With a complete circuit that "bias voltage" circit bleeds off through the sensor to ground. It is always there, just can't see it. The real key is knowing how to use it to your diagnostic advantage.
If you interested you can subscribe here for a 14 day free trial.
www.scannerdanner.com/join-scannerdanner-premium.html
Either way, thanks for the comment!
watch my "GM Fuel Tank Pressure Sensor Test" it will answer all your questions. Or if you have my ebook go to my chapter on potentiometer and signal circuit integrity testing
We get 5v on the signal wire when unplugged because in this pcm we must have a resisted jumper between the 5v reference and the signal wire which will give us a voltage reading when disconnected. Otherwise if there were no resisted jumper we should see roughly 0 volts on the signal wire when the sensor is unplugged...
Exactly! Nice job
@@ScannerDanner Is the internal resistor for the computer to test the circuit or does it play any other part in the function of the system?
@@philljustphill1656 no other function, just diagnostics as some psi sensors and potentiometer circuits don't use them at all
@@ScannerDanner Right, so this method could be used for any system that works in this manner I assume.
@@philljustphill1656 we are talking about the unplug it test and reading a 5v bias on the signal wire right? Yes! Every single circuit with this design can be used this way.
blessed my brother in Jesus Christ
thanks Jesus Christ for a teacher like you, I learning with you
I see you in Heaven
Thanks brother! I look forward to it! BTW, very timely comment as I am dealing with some things and to hear from a brother helps to clarify what I am doing. You'll see something very soon and know what I am talking about.
if the signal or 5 v ref wire is shorted to ground the ecu would automatically shut down you'll have a no start condition
NO COUES IT HAS A 5MAX/0-min potentiometer inside but why it gave a 5v when unplugged from the computer?
you make it look way too easy man!!! just common sense if you are mechanically inclined.thanks
BYU
when you reply to people like this "@name" i dont think it sends them a message letting them know. so they probably will never see it. just click the reply button on the right
what the hell does a ps pressure sensor do bc my dash has no inicator for it? Assuming it kicks on if the pump goes bad under the general check engine light.
What is confusing is the need for one bc if there are any issues with the ps pressure would not the results tend to be obvious and catastrophic?
have a 2005 toy sienna with an INTERMITTENT problem of locking up and hard steering in both directions however it does not leak a drop and there is no groaning of the pump... NOBODY, not even the dealer can offer a solution but to throw parts at it. Is this what auto mechanics have become? WTH ???
on a conventional system (without variable assist) the p.s. psi sensor is used for idle speed control. The ECM needs to know when there is a high power steering load to prevent stalling during parking maneuvers. On a variable assist power steering system where the steering gets stiffer at highway speeds, the psi sensor would be used in diagnostics for the system itself. The module would command a certain pressure and it wants to see that same psi on the sensor.
@@ScannerDanner ... Thank you for this. I received part of (your) answer from my the ever-so pleasant toyota parts lady and her colleage last week. They gave me the first part of your answer which is COMPLETELY unheard of in this day and age for a dealership to offer the consumer any other advice than..."bring it in."
So basically, the ps sendor does not have an end user idiot light feature and is just a sensor for the computer in the internal operations of the engine? Got it. Still doesn't explain the morning sickness of my rack. Used seafoam trans flush followed by dextron this weekend. There was very little contamination in the old stuff, performed flashlight at night metal flake test also, nothing. No groaning, no squeaking, no leaks. Only other thing that comes to mind is maybe there is a flat spot on the belt that is intermittently slipping during cold weather. Tech said squirting a bit of WD 40 on a suspect problem belt will verify. Checked the U-joints in the intermediate shaft, also fine. I wonder how many fatal car accidents happen from equipment failure and no one ever determines how or why. Thank again ...Scanner.
No ground should have more than 100mv.....
Ever measure a starter ground while cranking? How about a fuel injector ground when it is being energized? It will be way higher than 100mv
The scope is a cool tool and totally unnecessary. It could have done with a high impedance "cheap" voltmeter.
100% on this test, I'm just using a glorified voltmeter