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Do relays go bad? This one "ticks".

5.6K views 4 replies 4 participants last post by  CoupeDeBlanc  
#1 ·
I found the source of the ticking sound coming from the glovebox area of my '90 DeVille. I could reel the relay pulsing when it "ticks". The ticking sound corresponds to the clock, HVAC, and Fuel Data Center lights flashing off and on.
This relay has a mini-wiring diagram on it; circuits 30, 85, 87a, 87, and 86.
Can anyone identify these circuits? Is this relay a dealer-only item? Expensive to replace?
Thanks in advance.
Matt
 
#3 · (Edited)
All relays act basically like transfer switches (they use a lower amperage circuit to control a higher amperage circuit), this is done for safety purposes. If you look at the diagram, all relays are pretty much numbered the same (in my experience). I've only run into a few foreign ones that had no numbers on them at all. An easy way to test them (I'm assuming you don't have a multimeter and you are being careful, if you're not that skilled, have an extra set of hands there to hold one of the wires - if you touch the wires together or touch the positive one to the frame while they are connected to the bat you will be doing some welding- be very careful not to let the wires touch anything while you have them touching the battery posts) is to take 2 insulated wires, striped on both ends, put one on your positive battery and hook it up to #85 and the other wire on #86, if you hear it click one time, and then click again when you take one of the wires off, chances are its probably good. You'll need to test the continuity, with a multimeter, of the relay (poles 30-87a with no power to it, and 30-87 with power to it). If the relay tests out good, you have some other problems. Hope this is an easy to understand explanation. BJB
 
#5 · (Edited)
That's what I do first too. Very quick and easy.

Did you get the problem fixed mdogg? If not, I might have a fix for you.
My '89 did the same thing, right down to the relays clicking. My display and heater controls wigged out on me, along with one or two other items. I finally realized that the only thing that they all had in common was the BCM (Body Control Module) also called a BCU (Body Control Unit), which is separate from the ECM/ECU controlling the engine.
Pulled it out (took a long time to find it too!), got another one from the local parts store for about $100, swapped the chip (which the new one comes without for some reason) and installed the new one.
Problem solved.

Good luck.

Paul