Help....electrical question!

[jdp6000]

Some of the more powerful stereo's draw more power then is available from the fuse panel. What size fuse does the stereo call for???

I suggest you disconnect the power wire you hooked up for the stereo and see if the fuse blowing problem goes away. At least you will know if its a short or fuse size problem.

Jim

 

[AUSSIEVETTEMAN]

Bob & Jim,

She is blowing the radio fuse in the Vette's fuse panel. This fuse is a 10 amp fuse as the book says. There is another smaller fuse in the rear of the stereo itself, but that one is not blowing.

Could it be a fault with the 'anti theft deterant module'?
I had a study of the wiring diagram today and found that the radio circuit makes it's way through the 'ATDM'. If it is playing up, it may trip the fuse.
The wiring diagram is on page 8A-4A of the 1981 GM Corvette Shop Manual.
This diagram shows the power coming from the fuse panel (factory yellow wire) to the 'atdm' and then back to the stereo (as a yellow wire). It could be shorting, drawing enough current to pop the fuse.
The original 'anti theft' system doesn't get used anymore as our insurer wanted a 'triple stage', 'self arming in less than 40 seconds' job to cover the Vette.

I appreciate the help,

Cheers

Tony

 

[Bob Chadwick]

Try bypassing the circuit with a direct wire from the fuse box and see if that takes care of the problem. At least then you will know whether or not the problem is in the circuit.

This wire doesn't go to the ignition switch?

 

[jdp6000]

I realize the fuse in the panel calls for a 10 amp.But the question is what fuse does your new stereo call for? You say there is another fuse behind the stereo that does not blow? How many amp is that?

I'll explain why. If your stereo draws 20 amps and the fuse in the panel is 10 amp, it will evenutally heat up and blow. Its like the fuses in your house....one may be a 15 amp but if you hook up appliances that draw 20 or 30 or 40 amps the 15 amp fuse will blow. It does this for safety.

If your stereo is made to run off a 10 amp fuse and the fuse behind the stero is 10 amp then I would say the problem is something else. If its is something else it is being triggered by something your are missing. Something is happening at the instant your fuse blows. For example, the stereo works fine then something happens where the car draws more power or send power to something that causes the fuse to blow. You may not notice it...it could be as simple as you turning your headlights on or your windshield wipers on. If its is something else you need to make the fuse blow. Its trial and error...test the various circuits. Start the car, play the stero, then turn the lights on...wait....then turn the wipers on....wait...etc...etc..

Jim

 

[AUSSIEVETTEMAN]

...Try bypassing the circuit with a direct wire from the fuse box and see if that takes care of the problem. At least then you will know whether or not the problem is in the circuit.
This wire doesn't go to the ignition switch?...

Bob, I was going to try that today, bypassing the circuit alltogether.

On the diagram it shows a brown wire from the ignition switch (8A-10) to the radio fuse panel. (fuse is 10 amp). The wire changes colour after the fuse box and turns to yellow. It makes it way through the Anti Theft Deterrent Module, does it's thing and then finally makes it's way to the radio.
I am guessing, but I think all my trouble is coming from this module.

I will let you know how the bypass surgery goes.

Thanks again,

Tony

 

[AUSSIEVETTEMAN]

...I realize the fuse in the panel calls for a 10 amp.But the question is what fuse does your new stereo call for? You say there is another fuse behind the stereo that does not blow? How many amp is that?...

Jim, your suggestion was made by one of our 'diesel fitters' (civil machinery mechanic) yesterday at work. He said the same thing, there is something drawing too much current and popping the fuses. (He also said the current draw may trigger from a simple brake depress which turns the tail lights on) I told him that as far as I knew, there was only one thing on the circuit and that was the stereo. He said that there must have been something else there drawing too much current as a result of a fault (short or part malfunction). I went away until lunch and when I came back, I had read the wiring diagram a little more and had found that there was the 'ATDM' in the circuit as well. He said it quite possible that it was causing the problem, run a new wire from the fuse box and try that.
If I run a new wire, then I will have to disconnect the yellow wire going to the 'ATDM' as it will still draw too much current after the new wire is installed, and it will still pop the fuse.
The fuse in the panel is a 10 amp and there is a fuse in the back of the stereo, it is a 10 amp as well. This one does not blow.

Thanks for your help,

Tony

 

[jdp6000]

Follow the circuit that the fuse is on that keeps blowing. Someone previously may have spliced something else into it. I think what ever is causing your problem is after the 10 amp stereo fuse. Something is kicking in and causing your problem. There should be absolutely no spliced in wires on this circuit.

Is your deck faulty? Did you maybe connect to something on you deck incorrectly?

I have an 82 but I think the circuit is the same. Do you have a good diagram? I could always copy the one in my shop manual and fax it or mail it.

Jim

 

[jdp6000]

I guess it could be the antitheft...it runs off the same yellow...see diagram

http://www.misterbill.homeip.net/vette/wiring/radio_amplified speaker system1.jpg

http://www.misterbill.homeip.net/vette/wiring/radio_amplified speaker system2.jpg

http://www.misterbill.homeip.net/vette/wiring/radio_standard speaker system.jpg

http://www.misterbill.homeip.net/vette/wiring/theft deterrent system2.jpg

 

[AUSSIEVETTEMAN]

...Is your deck faulty? Did you maybe connect to something on you deck incorrectly?...I have an 82 but I think the circuit is the same. Do you have a good diagram? I could always copy the one in my shop manual and fax it or mail it...

Jim,

The deck is fine, it is new but I was thinking it was faulty for a little while there. Then I started to weigh it up and thought, new stereo or 24 year old wiring harness?
I have an original 1981 Chevrolet Corvette Shop Manual. It has colour diagrams and one at the back which covers a few pages.
I am guessing, but it may be like yours.

Regards,

Tony

 

[AUSSIEVETTEMAN]

I guess it could be the antitheft...it runs off the same yellow...see diagram
http://www.misterbill.homeip.net/vette/wiring/radio_amplified%20speaker%20system1.jpg
http://www.misterbill.homeip.net/vette/wiring/radio_amplified%20speaker%20system2.jpg
http://www.misterbill.homeip.net/vette/wiring/radio_standard%20speaker%20system.jpg
http://www.misterbill.homeip.net/vette/wiring/theft%20deterrent%20system2.jpg

Jim & everyone else who posted,

Yeah, same pics I have. Thanks for posting them, I know how much trouble you have gone to there to post them.
I took the old girl down to an auto electrician and he had a look at the circuit for me. Looks like I was on the right track with the faulty Anti Theft Deterrant Module. It is faulty and is drawing too much current. This is why the previous owners hard wired the other stereo to the CRTSY CLK circuit, which is a constant source of power. They gave up and put it in the 'TOO HARD BASKET' when the radio fuses kept popping.
The 'sparky' had a look and confirmed what I told him. Although I didn't want to tap into the harness, he has tapped into the ignition and installed it's own fuse for the radio. Looks like another part of the harness I will have to repair later, but at least it gets the tunes happening in the Vette!

Now, looks like I will need to find a new Anti Theft Deterrent Module for an 81 Corvette, yeah right! It is like looking for a needle in a haystack!

I appreciate all the time everyone put in posting their comments, cheers guys!

Tony

PS Oh by the way, Rob kindly changed our User Name!

 

[jdp6000]

Needles in a hay stack are my specialty. check your email.

Jim