VEHICLE RELAYS - Operation & Diagnosis

If you've ever wondered what a relay is and how it works, this is the video you've been hoping for... Other information about the FET book is at http://www.brighterideas.com

Category:

Autos & Vehicles

Tags:

• Voltmeter
• Relay
• leads
• ohmmeter
• ammeter
• ampmeter
• troubleshooting
• electrical
• electricity
• diagnostics
• powerprobe
• multiplex
• multiplexing
• PLC
• ECM
• diode
• kenworth
• peterbilt
• mack
• freightliner
• caterpillar
• komatsu
• testlight
• test
• light
• TESlite
• Enhanced
• Leads
• sterling
• volvo
• manitowoc
• p&h
• terex
• cement
• mixer
• tanker
• general
• electric
• locomotive
• thermoking
• corrosion
• wiring
• resistance
• voltage
• drop
• test light
• loadpro
• LOADpro
• ohm
• ohms
• law
• electronic
• specialties
• sullivan
• training
• systems

[tymeandtyde]

why do you need a relay to blow the horn? it's only 12 volts.

[bivideo7]

@tymeandtyde It's not voltage that matters, it's current. A relay is a switch. The coil operates on very, very low current, but can switch a much larger current. People want to "straight wire" stuff because they don't understand relays. Manufacturers use them for convenience, cost, and because you can make changes to electrical systems without a lot of trouble. It's also because computers can switch 0.120A (120mA) but not 15A. I've wired 480V circuits through relays with 12V coils. Learn relays.

[RapAndChopin]

Awesome vid, but I have a starter relay on my bike that I thought was blown because I tried to jump it with a car that was running (should have turned the car off) so anyway it doesn't work, but I can still start the bike if I take a piece of metal and touch both bolts on the top of the solenoid so that the current flows through them. I replaced the solenoid but it doesn't work, and I have to do the same thing and touch a piece of metal to the bolts on the top to engage this. any ideas? thanks!

[bivideo7]

@RapAndChopin 1st, the car running had nothing to do with anything. The system is 14V. Normal. 2nd, the problem is possibly with the coil, which is the smaller wire coming to the relay. Read DCV at both wires (or the one if only one). If it's EXACTLY the same as the battery volts (check it first) then the ground wire is open. If it's GHOST V, the positive is open. If either V is not 12V or 0V, there's resistance in the wire on that side. Ck out "How to Understand your Digital Voltmeter"

[bivideo7]

@RapAndChopin Make sure you're trying to start the bike when you read the voltages. This is critical. You have to try and make current flow to really see the problem. Don't ASSUME it's anything -- FIND the problem. Wires 80%, components 20%. The switch could be arcing (the relay is a coil) but you're better off going through methodically before ripping the switch off just because using tools makes you feel productive. Electricians go slow and check wires. Mechanics (I am one) start wrenching.

[coldpak82]

Great Video, I'm dealing with a Auto-shut down relay next to a Fuel pump relay there no Action with power going to fuel delivery or anything.Question if you pull the relay out.In the recept-part should I have a Ground and a Hot inside the female recept- part ?

[bivideo7]

@coldpak82 Watch the video again - then find a relay *that you know works* and pull the cover off. There has to be switched voltage to the coil, and the contacts will switch the other component. Put the uncovered relay in and squeeze. Watch what happens. If nothing, then activate the system and see if the relay moves. You have to first determine if it's the coil circuit or contact circuit...

[81eagle]

Hands down the best video on relay function I have ever seen. And shown way better than I learn at tech school.

[earnamint]

Terrific. This is an excellent video tutorial on 'How the Relay works'.

[TommyChevyBugle]

good video, ...are you sure your not the dad from "American Pie"?

[muscleammo]

wow... and i never thought i could understand relays :-)

you've worked a miracle my friend lol

[darren115]

top video!!! makes understanding how relays work much more simple. 5*