Truck is a 2000 F-250 SD. 4X4
There is a buzzing coming from the #1 relay (interior lights/cab light) in the fuse compartment under the dash when the truck is turned off, and the interior light is on (dim though). I replaced the relay with a known good one (from the intermittant wipers) and it still did it. Any thoughts before I start tearing things apart looking for a bad ground? Already tried spraying WD into the door latches, but no luck.
Thanks,
Karma.

 

anyone?????

 

I haven't heard a relay buzz, but it is a simple switch. One pair of contacts powers a magnetic coil, the coil pulls a switch. If it's buzzing with either relay, I would suspect the switch is bouncing back and forth. A bad ground is the easiest to test for, but it could also be that the relay is not getting enough power to hold the switch closed.

Any other odd electrical issues, with the wipers, headlights, ect?

 

Good to know about how a relay works. It is buzzing no matter which relay I have plugged in. I unplugged the original relay, and replaced it with the one from the intermitent wipers, and I know that it works. Just to clarify....this happens when the truck is turned OFF, keys out of the ignition, and me outside the truck. The problem is not constant, and the lights (interior and the one on the outside at the back of the cab) will come on for a minute or so, and then turn off. When they do come on, they are very dim. From your description of how a relay works, it would seem that there is a bit of power coming to the relay, but not enough to make the lights turn on brightly. Does the relay need power from the battery to power the magnets, to keep the switch closed even when the truck is off? When the relay has power, will the lights stay on? That would mean that when you open the door, it cuts power to the relay and the lights go off? The battery seems fine, but I have a spare, so I will change it out. In fact, I'll do it right now, and see if it fixes the problem. Will advise.
BTW-there are no other problems with the lights or wipers.
Karma.

 

No other problems means your GEM should be OK.

A relay is a standard switch, some have two poles (on and on). Most of the time the second on (resting postion) is left blank so the switch only turns on when the coil is powered.

The power going to magnetic coil is seperate from the switch side, the coil is used as a trigger to pull the switch. The switch has power from a fused source, when the coil is energised, the switch closes and sends power out to the accessory it's tied to. Sence the GEM is ok, we can assume for now that the coil side is ok. I would also check the fuse associated with the accessory.

 

Thanks. The fuse is ok. I changed out the battery for a BRAND new one, and the buzzing/dim lights came back within 1 minute. I opened the door, and the buzzing stopped, and the lights brightened. With the door open, and my head down by the pedals, I listened. I could hear occasionally, what faintly sounded like sizzling, or the sound that the transformer on a power pole makes in the rain sometimes (but very faint) coming from behind the fuse box. But WITHOUT any smell of burning electrical. Then the buzzing started again, and the lights dimmed. With that, I pulled the relay back out, and closed up the truck for the night. Tomorrow I will take the fuse box out and start chasing wires. Starting with the ground that goes to the relay. Sound like a plan? Any more help would be greatly appreciated. Damn electrical gremlins. Hope I can figure this out. Troubleshooting electrical problems at the mechanic costs big $$.
Karma.

 

it is a pain, but not terrible. Even if the fuse is good, if the terminals aren't shiny they may not make a good connection. I would suggest probing the relay terminals with a volt meter. Check the coil's power and ground and then check the power for the switch. I would check those before spending time pulling the box.

 

Pull all the fuses and put them back in...The connections get bad.



Dick

 

Ok, time to dive right in. I almost forgot, when I brought the truck back from Vancouver, I was sitting in it on the ferry and I would occasionally hear a rapid clicking from under the dash. Below and to the left of the stereo I think. I listened to it again today, and it almost sounds like a relay under there. Is that where the GEM is? What does it look like.
Will check back later.
Karma

 

GEM is General Electronics Module. GEM controls most all of the electronics, wipers, headlights, door lights, ect. I have a click in that area when I put the headlights to auto.

 

Well, still no luck. Couldn't get the fuse box out. Tried some other stuff, and thought I might have it, but then it came back. I took apart the interior light. There is a screw right into the metal that is the ground, and a wire for the positive. So I figure that right away I know that at least the ground is good. I removed the whole light assembly so that I was looking at 1 wire (+), and a screw hole(-). I checked with an ohm meter and I got the same reading as if I was touching the two probes together. Somehow, the positive wire is touching a ground somewhere? Is that right? I put the relay back in, and with it buzzing, I checked the wire and the screw hole with the voltmeter and got 6.9 Volts. Would point to a break in the + wire that was bleeding off about 5 volts.
By my basic understanding of electricity, I should not get a reading with the ohm meter between the positve and the ground hole.
Is the blower motor controlled by the GEM? I have noticed that occasionally the blower motor stays on when the truck is turned off.
Could all this be caused by a faulty GEM?
Karma

 

did you check the circuit from the relay control out of the GEM at the relay? Also check the right and left door ajar inputs at the GEM

 

Haven't done that yet, as I'm still not sure exactly where the GEM is. Under the dash I'm assuming.....and I don't suppose its labeled GEM..Ha. I'll RTM and see if it says anything.

 

The gem module grounds the relay. Plus 12 to the relay comes from fuse 4 10a. I would check this supply. And wiggle wires while the relay is clicking..
Do you have RKE? Normal heat controls?


Dick

 

What are your voltage readings at the relay?