Buzzing from relay box.

I AM NOT A MECHANIC:banghead: , just wanted to get that out of the way. Dad use to work on my cars, but he is gone now:frown: , so it is up to me. I have a '95 Taurus with a 3.8L 6cyl. New motor and tranny, bout a year old in car years. My problem is this, when I turn on the key, there is a very loud buzzing coming from what looks like a relay box that sits on top of my radiator unit, but under the protective flap that Ford puts over the radiator. There is a bunch of electrical wires that go into and out of that box, that's what leads me to believe that it is some sort of relay box. It buzzes REALLY loud before and after the motor starts. WHAT IS THAT THING:shakehead ??? Also, there is a wire that comes from that and goes to my fan. I can't get my car to start so I can't find out if my fan is coming on, therefore I can't find out if my thermostat is bad. AM I HAVING PROBLEMS OR WHAT:screwy: ? Please help me if you can. Thanks.

It sounds like you are referring to the Constant Control Relay Module (CCRM). This module controls the A/C compressor clutch, provides power to the Powertrain Control Module (PCM), fuel pump, and the low and high speed cooling fans.

The diagrams at www.members.aol.com/Rod2414738/Car_Stuff/CCRM-1.jpg and www.members.aol.com/Rod2414738/Car_Stuff/CCRM-2.jpg.

Sounds like there may be a bad relay in your CCRM box or a bad wire/ground to one of the circuits.

-Rod

Thanks Rod,

Is there any way to test the CCRM to find out if there is a bad relay or which circuit is bad, or should I just go ahead and buy the whole box?

I am ready to go to the parts place, so I hope you are here now. Thanks a million.

So, I took the CCRM box into the Ford dealer. I talked to someone in the service dept. and right when I started explaining my perdicament, one of the mechanics came in and agreed with Rod that it could be the box, or it was more probable that it is a short in a wire/ground to the CCRM box. Then I asked him if that would make my tachometer read 4500rpm when the motor wasn't even running, and instantly he said it sounds like a short. He said before I start throwing money at it, I should just pay the $75-$100 for the diagnostic test and maybe the mechanic will throw in the repair to the short. Is that the best thing for me to do now? Is there any way for me to find it? What do you think? Remember I AM NOT A MECHANIC:banghead: . Thanks for your help.

If you are comfortable with a Digital Multimeter (DMM) or better yet, an oscilloscope, and can safely backprobe wires, plus have a general understanding of electronics, you can diagnose this yourself. Using the diagram at the links I posted earlier, you can backprobe the outputs from the relay contacts to determine which circuit is effected. This is where the oscilloscope would be more helpful than a DMM, but a DMM will probably work. What you are looking for is a rapidly switching voltage. With a scope you would be able to see the square wave created by the switching/buzzing relay coil, with a DMM you may want to look for a lower than usual DC voltage or higher than nearly zero AC voltage. If your meter has a frequency setting, use that (as long as it can handle 14V input).

Specifically, you'll want to monitor pins 24, 5, 1 or 2, and 6 or 7. You'll backprobe these and connect to your red meter lead. Connect the black lead to ground.

Also, measure the resistance between pin 15 and battery negative. If this is more than 1 or 2 ohms (after you zero out the meter) trace the wire in location 15 to where it connects to chassis or battery ground.

-Rod

Well, thank you so much for your help. I put the CCRM box back on in order to take it to the shop, but I tightened it down real good and I also took the cables off and cleaned the posts and cables to the battery and the ground wire and guess what, everything works great. Thanks again.

I had a problem on an 87, it wouldn't crank one day, I was checking all the connections including the grounds, on the radiator top support towards the battery, there's a handful of ground wires, one ground connector has two black wires, one of these was loose in the fitting, these two wires came out of the integrated controller module on top of the rad, it's basically the same unit you're talking about, I resoldered wires to new connector, it worked fine..

Well, I drove all day Thursday doing errands :bananasmi and no problems. Then Friday, while going over to my girlfriends house to show her how to change the bulb in her tail light, my car died:dunno: (dumb car). I got it started, drove to her house and shut it off, but it wouldn't start again:headshake , so I went and bought a new battery and now it works fine, fine, fine.:lol2: Hopefully it will stay fixed this time.:p Thanks to everyone for all your help.