Skip the auto shop - Our mechanics make house calls

Q: Relay for engine management doesn't work unless the magnetized plate is pushed in. Please help!

asked by on

I tried to jump power from fan fuse to engine management fuse and it sparked then wouldn't start.. found that pushing magnetized plate in it would. Start ... put in a good working relay and it still needed to b pressed for constant power.... what would cause a relay to not work unless engaged manually... Please help i am in need of assistance ....

My car has 200000 miles.
My car has an automatic transmission.

A: Generally speaking, there are two separate ...

Generally speaking, there are two separate circuits inside of a relay. One circuit is, what I’ll refer to for the sake of this writing, as the "supply" side, and the other is the "signal" side. The supply side has a positive and negative post, and is what supplies voltage to the component being controlled, by way of the switch inside the relay. The signal side also has a positive and negative, but the signal side is what actually commands the switch inside the relay to close, and allow voltage to flow through the supply side. This is the reason there is typically four posts on a relay.

If you have to manually push the switch closed to get the circuit to work, then something is keeping the supply side from getting the signal necessary to close, and allow voltage to flow through the supply side. Without knowing the model of the vehicle, I’m not sure if the computer controls the voltage, or the ground, to complete the circuit.

You would need to get a wiring diagram and test the individual pins in the fuse box to see if there is a voltage or ground signal that isn’t being supplied when commanded. Once you figure out what signal is being received, then you have to figure out why. These situations are where a certified mechanic becomes valuable. If you would like to have this taken care of, a certified professional from YourMechanic can come to your car’s location to inspect the electrical system and proceed with the proper repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Engine does not get above 1700 RPMs even with the gas pedal is down all the way.

This could be caused by many problems. The first thing I would do is have a tune up done on the car and replace the fuel filter. A YourMechanic technician can perform these tasks if you do not feel comfortable....

Q: Door locks and hazard lights unresonsive

I believe it is possible that you may have a problem with your keyless entry module/receiver. If this control module is not working properly, this can prevent certain features that are activated by the key fob from working. These features...

Q: Car shakes when accelerating from 1st gear - 2001 Nissan Pathfinder

Hello. If your vehicle is shaking when accelerating from first gear, and not shifting into overdrive or the higher gears, then there is likely some sort of issue with the transmission. A few things that can cause these symptoms are...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...