Starting Issues
03-05-2014, 04:22 PM
#21
Senior Member
OK here's relay 101. For any simple relay there is a coil side and a high power side. Google a diagram and it will help you understand, I can't get one on my phone at the moment. The coil is an electromagnet. Apply power to it and it pulls the arm on the high side to connect the switch. The high side is always bigger wire and works like a light switch. So when you apply power to the coil side the high side is now connected. On the starter relay the small wire from the ignition switch is the coil, the ground is the mounting bracket. So you turn the key, 12v comes from the battery through the switch into the coil then to ground making a magnetic field. The magnet pulls the arm which closes the high side. High amp power now travels through the relay from the battery to the big wire connected to the starter. The small round part on the starter is actually kind of another relay called an actuator. When the power gets to it it makes another magnetic field to move the arm that moves the starter gear out to contact the flex plate. The reason for a relay is so you don't have to run high current through the key switch. The low current power just activates the magnet. Otherwise you would need to run those heavy cables to the key. Its the same basic design for all the relays in the car. For our purposes you don't need to worry about the other small wire. It is an on switch for the alternator. It stays on anytime the key is in the run position.
03-07-2014, 10:43 PM
#23
I
Thread Starter
Here's an update. I went to start up my truck yesterday and the starter was stuck on. Unhooking the cables wouldn't stop it or unplugging the ignition switch wire. So I pulled off the solenoid and to my surprise you could shake it and it sounded like their were bbs inside it. So I put the original one back on and problem solved. What a headache. So soon I'm gonna hit my wire connections with a wire wheel to clean them up real good.
03-08-2014, 07:08 AM
#24
November 2011 TOTM Winner
03-09-2014, 01:53 AM
#28
Senior Member
Sounds like the solenoid spring actually broke. Probably got a bad solenoid. Its good practice to test the voltages to verify the repair. You can then be sure that it was just a faulty part and it didn't happen as a result if some other problem. Plus it will give you the experience if reading the voltages. It should be about a 5 minute routine once you have it down.
