In this video I will show you how to test a power door lock circuit using just a voltmeter and a test light. The procedures shown in this video can be applied to all types of computer controlled door lock circuits, not just Subaru.
Engine Performance Diagnostics chapter 2
- how to determine circuit design with a voltmeter and wiring diagram
- how to perform a switch input bypass test
- what is the difference between a switch input and a conventional switch
- (Chapter 2) Switch Inputs, digital signals, module communication, hall effect testing
- Switch Input Identification Variables
- Honda VTEC System Testing (P1259 trouble code)
- Electronic Switch Inputs (a free ScannerDanner Premium video)
- Section 2 "Classroom Lecture" preview (an SD Premium video)
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no sir, but if you close the switch to ground and your ground voltage does NOT increase, your ground is NOT your problem. Make sense? So even though you would not technically be loading the ground, you have properly identified the ground is not your problem.
Paul you mentioned you can't tell by looking at the schematic on the circuit design, but to me it seems pretty clear that it's a pull to ground (pull down) design. If it where pull up wouldn't the common wire to the switch be a constant hot?
+ScannerDanner followed the link to mitchels, and in the small print it says it does not cover the power locks in the manual. guess to get the schematics you need the full shop package, not DYI version.
But did learn something. Last power windows I had were good ol, power switched. Hadn't even thought about the stupid computer getting involved. Guess for the remote to work you need it that way. Maybe low volt/amps will make switches last longer.
But that is where you need to hack to get your cop proof windows that will only roll down 2 inches.
Come and be part of my community! IT is free to join the forum. (you do not need to join to read and get the information you need from the above link)
Thanks for this video. My 03 subaru impreza was locking but it was NOT unlocking. I was able to use this video to truobleshoot and test. Thanks to this video i knew what 2 wires i had to look at at the plug on the door. Yellow wire is to unlock. I tried jumping it with a test light from a ground like he did here and nothing happened but when i jumped the locking wire the doors locked just like it was with the switch connected. So i new it wasn't the switch. I checked for continuity from the door switch to the module or computer and found i did not have continuity on the yellow wire which turns into yellow and red when it gets to the module plug. So used a wire to jump from the yellow wire on the door plug to the yellow and red wire on the module, with both plugs connected and it unlocked the doors so i knew the issue was an open circuit on that wire. I didn't feel like taking everything apart to check where the wire broke exactly so i decide to just run a wire from one end to the other and bypass that yellow wire. So far i have seen no issues whatsoever. Time will tell i guess but i have a feeling there won't be any issues. Thanks to this video i was able to fix this. Its amazing what you can fix by just doing some research online.
Hey Paul you say that you can use a incandesent test light to bypass a door lock or power windows if the switch goes to a module.i tested my passenger side power windows and was able to bypass the switch with test light to ground but when i tried this at the drivers side master switch it did not work.
? I was on the correct wire .I used my dvom and checked i had just over 9 volts on the wire and when i activated the switch it went to just over 4volts..why did it not pull close to ground? surly if i can bypass the passenger side i should be able to do the drivers side.Could you please explain why this test is not working as the switch goes to a drivers side module ..
I understand the section 2 switch inputs but this has me confused now and i cannot understand why a bypass test cannot be done on the drivers side with the test light .
The circuit all works fine when i use the switches . I was trying to learn using a real circuit to apply the tests from your lectures.
Bad ass video Paul you’re a MASTER. At work one time I had a Hyundai Sonata. It had some problem with the door locks. I can’t exactly remember what. But when I started the video I wanted to ask you this same question. And that is why when i tested power wires with my test light did the actuators in the door locks-lock. Now I know why. Even though i don’t know everything about electrical right now I understand how you explained it in the video. That was the same exact question I was going to ask you. I was baffled as to why the locks actuated when i used my test light. Thanks for the videos!
Paul, I followed a small course using a arduino as a mockup car CPU. Creating pull up/down situations. Relais activated from the "CPU" by a switch circuit etc just playing with it would give your students also a good feel or better feel for that kind of circuit.
great video but i think u switched between the pull up and pull down methods to monitor the switch
a pull up method : the control sends the 12V or whatever to the switch which is connected to a ground . when the switch is on the 12V from control side turns to 0V and that's how the control knows that the switch is actually pressed so by grounding the the wire coming from the control to the switch the control acts if the switch is pressed
correct me if i'm wrong please.
No, I think he was right. Like you said the module sends 12V or whatever to the switch. When the switch closes it allows the current to flow and the voltage to drop across the resistor in the module and the current flows to ground now that the switch is closed. The voltage drops to zero. Thus pull down. The voltage was pulled down from 12 V to 0V. If the signal wire was 0V initially, and you closed the switch and the signal wire raised to 12V, then you would have pulled the voltage up to 12V. Thus, pull up design.
I got problem ive checked door wires all good relay movearound good fuses good no power door lock on bothside its a 02 lincoln navigator but I checked housing connection n I got no power put test light tried finding power n nothing wut could it b any advice
I was wondering if you can give a short cut in how to test a system without a bidirectional scanner I have an 03 envoy with a problem with the 4x4 the service 4wheel drive light is on and it's saying short to battery positive can you give me some advice
Hey Dan,Good video,I'm having problems with my central locking,It wont lock or unlock when I push the key button,I hear the relay clicking under the glove box,its a 2007 rx8.I have a keen interest in automotive electrics,I will check out the rest of your videos for help,thanks.
+ScannerDanner Hey Dan ,making progress on fixing Central Locking,I have power and signal as far as the actuator on drivers side door although its 4.8v,Im going to take the actuator off and test it later.
+Josenildo Silva On my Premium channel yes. It is an 11 hour course. Here is the link for the Verus playlist. https://www.youtube.com/playlist?list=PLM4TD8VJ3gj_fg_miN2Uu0yRMc5xSySy3
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+Josenildo Silva sure. It is a monthly or yearly subscription. It's 9.99 per month or 99 for the year. As an eBook or paper book owner I'll give you a coupon for a free month. Access and viewing is exactly like any other youtube video. As long as you're signed into your youtube account you'll be able to watch them any time you want. Currently there are almost 300 videos on that channel . email me for your coupon through my website. Thanks!
Hey Paul, I have been watching your videos and classroom lectures for a while now and have learned alot. about the 8:00 minute mark you are checking the ground with the volt meter
and it shows good, it stays below the 100 mv range witch is a good ground. Just a thought here, if the ground was bad the voltmeter would have risen to the 11.39 volts that was coming from the
signal wire, right.
I would like to correct something that I posted earlier. Many late modern cars use a ripple counter connected to the motor to instructs the window to stop when it reaches the top and bottom limit. There are a given number of commutator impulses [ripples] as the window goes from open to close and these are used by memory chips to stop the window as it reaches the limits
Paul, I am happy that that subscribers like me, Tom and Off-course you are interacting very much and sharing the knowledge across various states. I like to give special thanks to Tom A in providing the tips. Subscribers like Tom A are credit to our forum. This really shows how well we are working together in building out knowledge. I am very proud to be part of our group. By the way I am software engineer, not Mechanic.. if u need any help on my side, will do it for free for the respect I have
nice thank Toms. So with this design would it be safe to say that a mechanical binding of the regulator would cause this Auto Up or Down feature to be limited from the thermal contact? I would think this would be in place even if they used the hall effect position feedback or the range limit switches as sivucit just stated in his research
part 2.. in case of Toyota, or Nissan, they don't use pulse or interrupter concept as I said in previous post, it uses something called limit switch. which is placed in such a way that if the door went all the up or down the switch will be enabled to disconnect the power..
Thanks Paul and Tom A. I did some research in the weekend go some good Manual from Honda. What it does is, window motor have 4 wires in addition to regular + and -. These 4 wires are called pulses. It has hall effect sensor which look at the rotation of motor and generate pulse similar to our crankshaft and if the pulse is more(as per the programme) means something is obstructing or have reached the top based on total duration of pulses in ms,decided to disconnect the power. continued
Hi Paul and sivucit. There is a timer that interprets a short duration touché to mean that you desire a complete [toll window] open or close function. a longer duration touché will inhibit the timer to move the window as long as the button is depressed. When the window reaches its limits the current requirements increases drastically and this opens a temperature sensitive contact in the window motor and causes a shut down the contact resets after a short duration. Thank you for this video .
It certainly could be that. I know blend door actuators will have potentiometers inside of them but I've never seen that for a window circuit. I supposed you could experiment with it by placing something in the path of the window. (I WOULD NOT RECOMMEND DOING THIS! YOU MAY BREAK THE WINDOW). If the auto up feature hits the block and then stops, then you will know that it is a current surge that triggers the off feature.
Paul, quick question.
1) when i press the power window up button once (no need to pull up all the time), the glass window goes all the way up. again just pressed once. what is the design that helps the computer to know that the windows is all the way up and it can stop the feed to the motor. any insight please. i was told that when window is all the way up, resistance in motor winding would trigger the computer that it is all the way up.
any clue or tips u have.
Yes, it I a fix I was guessing on 2 of the wires I see some voltage 12 input and ground, also on 2 wires up and 12 steady and down pulsating is like duty circle ho I mean from. 0 to 5 volts only when I activate. Front left motor only, there are about 4 wires more that I do not see any activity at all when I operate all the other motors
The car is 98 Honda accord 2.3 l sedan
Thank you I appreciate your time.
with the new master switch all the motors works just fine,the purpose of the question is for learning circuit design.
to learn i compare reading of faulty and good working switch on reading back probing them the readings are identical I do not see activity changes in voltage but the deference are one works and the other does not I took readins plug and unplug I do not see if it is pull up or pull down to do by pass. do you know how this work thank you.
so in the Up position you see 12 and 12?
and in the Down position you see 0 and 0?
If this is the case you have either a broken wire in the door jam or a bad switch. I think you said you changed the switch, so look for a broken wire in the door jam
- with the new switch plug in I gave then power to up and down wires and the motor work at this time to recheck my self plug back the old switch same result than before no reaction how this system works? It has multiplex control. also I have some curiosity about the motor I connected the volt meter at the motor harness and activated the switch close I read 12v on up or down,plug or unplug 0v. so I gave it power to the motor and did not do any thing checking my volt meter read4v?TKZ
Hi, Mr paul i have couple questions here I a have 98 accord ex sedan 2.3l I had some issue with RL window motor not working i suspected a switch doing some by pass test I unplug the switch and the 2 wires that goes to the motor up and down did not change state, so I decided to give it some power and nothing happens than I plug in the switch and give power to wires to motor nothing happens all this test where done with the faulty switch. Know I plug in the new switch and did the same test
Thanks. And also, I don't really understand how you would get 12v on the signal wire going to the computer with the connector plugged in on a pull-up type circuit design. I understand with it unplugged you would get zero volts but its with the connector plugged in that I have trouble with understanding, does that mean that the switch has continuity with the signal wire always until you depress it and open the circuit or what....? If can help me out with that, that would be great.
Hey, scannerdanner would it possible for you to give some examples of some pull-up circuit designs of door lock systems, or some vehicles that have these type of circuits designs?If so, that would be great.
Talking about computers I just got my A/C fixed I got the factory manual very good info. It was a 1991 toyota camry 4 banger it had a bad ground going the the a/c computer . I checked by hooking 12v to compressor and it made the car cool and after a while I got to the computer and grounded the ground with a test light and the complete system come on . That computer sure does a lot of stuff for a car so old.
Sometimes computer controlled door lock and window circuits can be tough to diag, especially if they have timers (as in BCM controlled circuits designed to provide power for 30 seconds or so after you turn the vehicle off - as long as you don't open the doors). Wiring diagrams just don't show enough detail sometimes. Anyone who has been stuck on a circuit like this for any amount of time can appreciate this video. Information like this can save you hours of diag time. Keep 'em coming!
@televisionmacforum in some cases this behaviour can be made available by flashing another country code in the central locking module. How and what is make&model specific but i bet there is a way to enable it in your car. Go check out a forum or website for your model and ask around.
Good stuff Paul.
Our 2009 Honda crv can't do the driver only door lock trick but the US version can.
Very annoying not to have such a basic safety feature. Also missing in the UK is the auto door lock feature as you pull away.
The integrated module has a drivers side only function to it. The key less entry module looks like it pulls the circuit to ground just like the door switches. It could however only partially pull the circuit to ground, which would indicate to the integrated module to do the drivers door only. I'm not sure. Or it could all be done by logic in the integrated module. I should have monitored the circuit when using the key fob.
There's 3 wires going to door motors. A simple door motor can be driven by two wires so my guess is that there is one dedicated wire for the driver side door motor. The logic (when in locked state, first unlock signal opens only driver door) can be easily handled by the module internally, no need for special voltage levels.
Thanks for another great video! My first step when I do any sort of diagnostic where I need to know how the circuit works is pull up the system diagram in Mitchell. Watching all of your videos over and over again I'm able to quickly and accurately make my way through the wiring diagrams and move on to component and circuit testing. Every repair made is backed by proof now!
good video once again. i hate how the new(er) wiring diagrams don't show jack. you really have to dig through diagnostic trees and troubleshooting stuff to find any kind of information on circuit design. its like pulling teeth from the manufacturers. at least thats how toyota is.
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