Best Way to Bench Test a Leak Detection Pump LDP
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- Опубликовано: 26 ноя 2024
- In this video, Tom Morgan Autologic Technical Support Specialist demonstrates the best way to test a leak detection pump (LDP). This test can be used to confirm the LDP is functioning properly and sealing during evaporative emission system tests.
Remove the guessing when it comes to knowing if the pump is working or not. 
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Thank you. I'm a professional mechanic but work at an independent shop. A lot of these tests aren't available but they are needed to do a proper diagnosis and repair. Far too often guys at independent shops are forced to throw parts at a problem hoping to fix it due to lack of proper diagnosing techniques. And this was laid out so even a novice can understand and replicate it.
Perfect. Just what i was looking for. The Evap system is kind of odd until, you understand it. This test can potentially save me $200. The best part is the simplicity of the test and explains a lot. Thank you!!
I like what you've shown. I'd suggest showing what a bad value looks like. Maybe demo how to check for a short I'm this system. I'm chasing a persistent P1494 Leak Detection Pump code and have replaced nearly every component and hoses.
Yeah I'm dealing with the same shit now on my 2017 VW MK7 golf 1.8 T constant engine light on for P0456 small EVAP leak and mechanic suggests replacing canister purge valve as gas tank appears to be perfectly fine but I don't have any of the stuff in the video so I'll have to make him do this shit.
Hi will a bad dtml pump cause gas cap to get wet in the gasket side. Thanks.
I am going to do this to my wife's 2005 Liberty 3.7L. When she shuts off the Jeep it makes a 2 second farting noise that comes from the pump (I can feel it vibrating). She also got a P0440 code but the evap solenoid was not holding pressure so we think the solenoid caused the code.
Just wondering how you made balloon inflate with vacuum ??? Are you using a pressure supply not a vacuum supply ???
Thats what im trying to figure out to
My vague understanding, short version -- vacuum (momentarily triggered by an electric solenoid valve) pulls a diaphram; then, when the electric signal is turned off, the vacuum line is closed and a spring returns that diaphram to its original position. The movement of the diaphram, in conjunction with little valves that open & close, pulls in fresh air and pushes it into the closed EVAP system...creating pressure. This video explains --- ruclips.net/video/MSWqUpREpQA/видео.html
It is a vacuum source just like he said. Some vehicles use engine manifold vacuum, some have a vacuum pump. This device uses vacuum as a power source, the diaphragm inside the LDP is pulled against a spring and then released cycling rapidly the pumping action of the diaphragm makes enough air to begin to inflate a balloon.
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This is not a complete test of the LDP. You also have to test the position switch inside the LDP. The +12 volt supply to the LDP is continuous and the wire from the other end of the solenoid is what is supposed to be connected to ground (the same as what the ECU does). Connecting and disconnecting the ground is what cycles the solenoid and pumps up the balloon. You also have to place a voltmeter on the wire coming from the internal switch to see if the switch is operating correctly. The switch wire should cycle between zero and 12 volts. Another thing is to monitor the engine vacuum going to the LDP with a vacuum gauge during the test. When the solenoid is closed it should read normal vacuum. Then when the solenoid is opened the vacuum should drop momentarily and then recover back up to normal. However if the vacuum drops and stays lower than normal then the rubber diaphragm inside the LDP is leaking so the pump must be replaced even if it still manages to pump up the balloon. A leaky diaphragm is the most common problem with these pumps.
This video shows how to bench test the pump for proper sealing when leak testing. Thanks for the additional notes on testing when the pump.
He is testing the electrical to mechanic part of the pump nothing more. If it passes then yes more testing should be done.Wiring harness test to see if it gets a
good ground or signal voltage from the computer which is switched of course not constant voltage. Most cars switch ground connection via the computer.
@@hestheMaster As an update the problem in the Dodge Caravan I was working on turned out the be a bad wire going from the sensing switch on the LDP up to the computer. I ended up running a new wire from the LDP to the computer outside of the wiring harness. I think there is probably a butt connector inside the harness that pulled apart. Once I ran the new wire the persistent, recurring P1494 codes finally went away.
@@joevignolor4u949 Had a Jeep Grand Cherokee, battery acid destroyed wiring harness under battery tray, had good ground, batt volts at LDP , load test circuit and short trace the power wire to under battery tray, cut open harness and found 8 damaged wires, So others beware if you see battery corrosion residue on these dodge products take a good look at those harnesses under tray.
It would be nice if you explained where you connect the other ends of the fused jumper wires to. Without that info the your video is worth nothing.
Before following this advice please watch you tube channel "James Danner". Title of video Chrysler Dodge Jeep leak detection pump p0455 large evap leak. YOU CAN DESTROY THE LDP BY THE TEST METHOD PROPOSED!!!