What Is A Voltage Drop Test?

A voltage drop test is possibly one of the most under-rated tests to be done when diagnosing a fault. It is a simple test and yet yields definitive results that can make your diagnostic time and effort minimised.

#voltagedrop#diagnosis#automotivemaintenance

Disclaimer:

MiracleMAX wants you to be safe, however, no guarantee can be given against improper use or unauthorised modifications on the information provided. The repair shown in this video is carried out at your own risk and any property damage or injury is your own responsibility. Please ensure you carry out this repair safely using approved safe work practices, correct use of recommended tools and equipment. This video is educational only and is no guarantee of a result if done incorrectly. Any injury, damage or loss due to incorrect use of tools, information or equipment is the sole responsibility of the person carrying out the repair and not MiracleMAX.

30 Million Times (instrumental) by RYYZN

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[yearsaprepperr.jtilbury.]

G`day Max,  
Problem solved, Pajero 2002 DID (Zexel VE Pump 3.2 ) had a No start with Crank, tests, Stop solinoid, fuel tank pick up, power to all sensors 12vdc and 5 VDC rail, Glow plugs, all relays load tested and signals from sensors on ocilioscope (Nice square wave pattern, after a quick chat i did a voltage load test on the negatve wires from the speed sensors on the pump (there are 2 speed sensors Like a crank angle sensor 3 wire ) the NEGATIVE had a 2.4vdc drop to the negative on the battery, Bingo i jury riged a wire to the sensor common and hit the key and all good,
Thanks again for the advice
Robert
Nowra
NSW

[colinreid]

Voltage drop is often overlooked in diagnosing electrical issues. I remember working on mk3 Cortina’s that had a VD of 3 volts in the headlight circuit due to under size earth wiring and was upgraded as per service bulletin.
Fluke has an excellent pdf on VD testing for vehicles on their web site that may help some confused people.
Modern vehicles are intolerant of voltage drop and can lead to all sorts of issues.

[johngibson]

Thanks again max I will be using this to check out for voltage drop for my vz sv8.

[bigmedge]

Very methodical explanation Max . Just need 1 thing clarified plz : since the 2.6 v voltage drop ended up being on the positive side of the load, wouldn’t that mean that this drop happened somewhere in the cable that’s between battery + & alternator output - in turn, indicating that this cable must be replaced since it’s the culprit of the drop?

[markshort]

Cool max, i didn't know a multimeter could be used like that.. i just learnt something that I'll be using a lot from now on

[jamese]

Thank you. More explanation/details for each test would be helpful.

[rjansen]

Hi are you in australia? I am so frustrated trying to find somebody to do this test for me! I'm in nsw.

[MrWilliam.Stewart]

FYI, it isn't when you drop your millimeter.