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Help! Blowing CTSY/CLK Fuse on '84

dmbpettit

New member
Joined
May 7, 2016
Messages
3
Location
Loveland, CO
The CTSY/CLK fuse blows in my 1984 Corvette each time I turn the ignition key. For several years, the door locks, interior lights, horn, etc (all the systems that tie into the CTSY?CLK fuse) have not worked. I found various wiring diagrams online. I would like to find the point where the Pink/White wire that connects to the fuse box, splits off to all of these systems. I imagine there is a relay or junction box of some sort under/behind the dash. I wanted to start my trouble shooting at this point. I plan to remove all of the wire and re-attach one by one until the fuse blows, which should indicate the trouble area.

Thoughts on my process? Where might I find this relay/junction box?
 
First, let me welcome you to the CAC Forum!

Second, by your question, I am perceiving that you do not have a copy of the '84 FSM (Factory Shop Manual). I'm not talking about the puny generic Chilton's or other waste-of-time books. You need the real thing (it's actually two books)!

It's interesting that the fuse blows when you turn on the ignition, because the CTSY/CLK circuit is always hot, even with the key off, so there's some link between the key-on circuits and the CTSY/CLK circuit that's causing your problem. That means the CTSY/CLK circuit itself does NOT have a short circuit.

By my evaluation of my '84 FSM, I'd suspect the Interior Lamp Delay Timer as a possible link. You have stated your interior lights don't work, so that make me wonder about this module. This module is located behind the pass. side knee panel, and is taped to a large wire bundle, near the turn signal flasher.

When you're chasing a problem with blowing fuses, there's a way to keep from spending so much money on fuses! My "gadget" is an old, but good, headlight, wired to an old, burned out fuse. Plug this thing into the offending location in your fuse panel. When you have a short circuit, the lamp will shine, but nothing will smoke! If you don't have a short circuit, the lamp will be dark and your accessories will work as normal (click on the pic):

DSCN2871.JPG
 
I started removing the center console and various dash parts in my search for the wiring. I then remember something I head read on the forum about someone having issues with their cigarette lighter. I decide to disconnect from the back of the lighter...and everything works! (Sort of). No more blown fuses. The interior lights, under the hood lights, the clock, door locks, all started working. The radio doesn't work. When I try to change the station, nothing happens. It also displays strange radio frequencies (stations such as 039 or something). Could just be a worn out radio. The horn doesn't work so I may have to remove the console again to check the horn relay. Anything else I should check there?
 
I decide to disconnect from the back of the lighter...and everything works! (Sort of). No more blown fuses.

Sorry, but that makes no sense. There is no relationship between the cigarette lighter and the ignition switch circuit. Good luck!

:w
 
The horn doesn't work so I may have to remove the console again to check the horn relay.

When you press the horn button, do you hear the relay click? If it clicks, check to see if you're getting 12 v. to the horns. If you can't hear a click, it's more likely to be a problem with your horn button. Pry it off carefully from the center of your steering wheel, then carefully disconnect the wire from the bottom of the horn button. Touch this wire to the center bolt of your steering column. If the horns honk, the problem is corrosion inside your horn button. It can be dis-assembled to clean the contact areas. Use a little di-electric grease to prevent future corrosion.

:w
 
I'll take a look at the horn contacts. I don't think I was hearing any click coming from the relay.

Regarding the cigarette lighter, according to the schematics I have, the CTSY/CLK fuse is connected to the cigarette lighter. I am thinking the fuse doesn't pop until I turn the key one click because the cigarette lighter is not hot until then, unlike newer cars.
 
The lighter is HOT at all times. I've mentioned this before in another post, but make sure a coin isn't down inside the lighter shorting it out. YOU'D BE SURPRISED!
 

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