ninjaneer911

1986 convertible with butchered radio and current draw to the 15A courtesy fuse. Current draw details:
1.when inserting the 15A courtesy fuse, there is a strong arc (indicating there is definitely a draw on that circuit)
2.if the 15A fuse is removed and replaced the interior courtesy lights come on, then time out again. This was done with the door open switch closed.
3.no visible lights (at night) are on while the car is sitting
4.When the 15A fuse is in:
a.2 door and 1 kickpanel light all work
b.“key on/door open/headlights on” chime works
c.glove box light recipticle is missing completely, but hot wire still has power (don’t care right now)
5.I have disconnected a hackjob aftermarket radio install, all wires are disconnected at the moment
6.Vats is still on the car and has prevented the car from starting once or twice (don’t care right now) but it cranks fine now

Possible related issues:
1. power antenna is stuck at half staff, not sure if it works (don’t care right now)
2. dimmer for the gauges does not work, gauges do however(don’t care right now)
3. horn was not working, then did, is not again. When press a clicking comes from the display ( behind the “door ajar” light)
4. under hood lights have been unplugged (don’t care right now)
5. cigarette lighter was straight wired to battery and grounded to a support
6. I found the factory cig lighter power wire has power at all times and good ground wire too (not sure why straight wired.)
7. everything else seems to work ok

Questions:
1. where should I start looking for this draw on the courtesy circuit?

87 vette 81 big girl

Pull the relay out for the power antenna.

See if that eliminates the current draw.

Then go back into the radio head wiring and double check there again for more problem wiring.

Takes patience. You have good troubleshooting skills and electrical knowledge.

You will find the problem soon I believe.

brian

87 vette 81 big girl

Also check around the rear license plate light.

Because I had a short in the wiring for the outside rear lower bumper light on my 1987 Vert a few years back.

Wiring was rubbing against the long spare tire carrier bolt right behind the rear license plate.

Was blowing courtesy light fuses and driving-parking lamps.

If you remove the rear license plate on your 1986 Vette, you will see the rear light wiring.

2 wires.......... Orange and white. about 16 guage wires.

Orange is 12 volts hot.

White wire is ground. Controlled by Courtesy lighting module. Switches ground on and off.


Shut the doors on your Corvette.

Walk around back by the taillights in your dark garage, below the rear

license plate you will see the light below the rear bumper go on and

off, Its on time delay with your interior lights when working as it should.


BR

jfb

Mister, you have your work cut out for you because the courtesy fuse powers the following circuits:
LH and RH map/courtesy light (on door panels)
Heater a/c controller
Courtesy light timer
Radio
LH and RH footwell courtesy light
Audio alarm module
LH and RH engine light
Cigar lighter
Glove box light
Telltale assembly
Delco Bose amplifier relay
Spare tire light
LH and RH cargo compartment light
Antenna relay

Good luck!

Louiseven

Subscribed! I have a 1986 base coupe and I am having very similar issues with the same fuse. I too just pulled a rats nest of a hack job on an aftermarket stereo. When the fuse is in I hear a door or key chime the glove compartment light works and strangely intermittently while applying the brakes the passenger side wheel well light will illuminate!
This fuse will last for about minute to a day before it blows. I am in no way experienced like the OP so I will watch this thread closely! Thanks!!!
I noticed that the antennae wires have been clipped. I will also try pulling the antennae relay later today. As my fuse panel does not have the door. Which is the antennae relay?

ninjaneer911

Big G, sounds like two good places to start. Thanks for the advice!

JFB, yeah i sorta figured it was a large circuit. I have the shop manual and elec diagnosis on order as of today. Agent 86 sent me some diagrams to get started. Looking over the list you posted, i wonder, with the factory radio coming out:
1. Will the audio alarm module failure possiblity go away? It should no longer be connected correct?
2. Same goes for the Bose Amp Relay? (I dont even know if my girl had the bose amp)
3. Do I have LH RH cargo lights? (convertible) Where are they?
4. Of those on the list, which ones are likely to draw current and still appear to be functioning. Something for me too look at after i emlimnate the components that dont work (antenna)..

Loui, not so much experience.. just bitter determination to make her driveable...

All, Good response for my first post on CF! thanks!

AGENT 86

Is there a large draw when everything is off and doors closed, or are you blowing the fuse ?

Was step 1 done with the door switch closed ? If so, are you sure you closed the correct switch, being as there are 2 ?

The horn relay is behind the info center.



Here are all fuse block details, should help to narrow down the problem.

http://members.shaw.ca/agent86/Fuse%...%20Details.pdf

jfb

1. It'll go away when it gets wired back up correctly.
2. Same as above and I'll bet all my assets your car had Bose amplifiers.
3. Yep, convertibles have cargo lights, they are on each side of the cargo compartment behind the seats.
4. Sorry, someone butchered the hell out of your wiring system and I am not clairvoyant, so you will have to trace power on every wire to the accessories on my list that don't work.

hooked073

What is the problem you are chaseing? Were you looking for a draw? You will most likely get a arc from this fuse when removing and replacing. At that point you are activating at least one relay or timer. How many apms are you pulling once the fuse is in and everything has timed out?

ninjaneer911

Well here is what i have learned so far (beside the fact that like Hookd073's icon)

1. the monkey who decided to design the car with two door switches is no friend of mine
2. the monkey who decided not to repair the completely disentigrated passenger door switch (rear) is no friend of mine either
3. the antenna relay didnt have power because the radio is out (duh)
4. under hood lights have been disabled (unplugged and i cant find the driverside plug, no biggie yet)
5. my spare tire light plug was, well lets call it in "disrepair" (not sure forums rules on profanity)
6. The door adjar alarm worked intermittenly then stopped while i had the courtesy fuse in to troubleshoot. It sounded fine for a while, now it only tones one time. Could this be an indicator that the timer is bad? the lights did time out while i had the doors closed.
7. still no horn (will jump the relay when i address the obvious)
8. the car did have the bose system. im goin after the bread box and amp relay soon.

Long story short, I think im on my way to the promised land...

jfb

You are making progress and you clearly like abuse!

ninjaneer911

JFB,
what do you think about the door adjar alarm only chiming one time? is that a possible cause of the draw or is it more likely that is a syptom of a bad light timer?

and

My running lights came on the over the weekend at some point. Does the car have daytime running lights that always come on when running or is the photocell bad? There doesnt seem to be a problem with the exterior lighting system.

As an engineer, i feel life is simple when the problems are complicated.

jfb

Door ajar chime should continue as long as the ajar signal is applied to the chime circuit. I suspect a defective chime.
Running lights don't come on except with the headlight sw in parking light or headlight on position. Check the buggered wiring.
I am a BSEE and I don't find complicated problems making life simple, to each their own!

AGENT 86

http://members.shaw.ca/agent86/Chimes.pdf

jrichardson

I have an 86 coupe.This problem started for no apparent reason. I was turning left onto the interstate and noticed the A/C stopped working. The control head went dead and the fuse had blown, replaced the fuse and it keeps blowing immediately.
The Anitlock light is on the info center. The upshift light will come on while cruising at highway speeds. Lift the footfeed and it goes out. I have been unable to find any wires bad but am having trouble getting the knee pad off under passenger dash. I have taken the two nuts off but still cant get the pad off. I pulled the controlhead out, but found no problems or bad wiring there.
I have run my hand up to the back of the fuse box and tried to find a bad or shorted wire but to no avail.
Any help getting the pad off would be nice then I could see the wiring from the fusebox a little better.

Hooked on Vettes

Are you sure it's the AC fuse blowing?
The AC fuse is 25 amps and not 5 amps.

If it is the AC fuse, do you have manual AC or Auto Climate Control?

If you have manual AC, unplug the connector at the Control Head and see if the fuse blows.

If you have C68 Auto Climate Control, unplug the AC compressor clutch at the compressor.

Cliff Harris

You really should start a new thread instead of posting in a thread that is completely unrelated to your problem. That is known as "hijacking" the thread and it's considered to be as evil as it sounds...

"The control head went dead" implies that you have the C68 automatic HVAC system with the digital temperature display. The control head gets power from the GAUGES fuse, so check that out.

According to my FSM on page 8A-64-4, the A/C fuse goes to the compressor. Try unplugging the compressor and see if the problem stops. The compressor is controlled by the BCM (Blower Control Module) mounted on the evaporator housing. You might have a problem in the BCM or the wiring/connectors between the BCM and the compressor.

My ABS system has never had a problem so I have no experience with it and can't help you with this.

Now we get to guess what kind of transmission you have. I'll try 700r4. The upshift light will come on if you're going over 40 MPH in Drive. That light tells you to shift into OD. Assuming you ARE in OD, there is a switch inside the transmission that tells the ECM that it is in OD. If it sees that signal it will not turn on the upshift light if you're going faster than 40 MPH.

The transmission has a 4-pin connector on it that has two wires in it. One is for the OD switch and the other is for the TCC (Torque Converter Clutch). There might be a problem with that connector or the wiring associated with it.

I assume you're talking about the "dash pad" -- the styrofoam thing on the top of the dash. You have to take off the instrument panel bezel to get access to the screws above it. There are also two screws above the center cluster. The last screws to take out are on either side of the defroster duct. These two are really long. It's possible that you also have a screw above the fuse panel, but most cars don't have one there (mine didn't).

Mark1986

After spending countless hours repairing burnt wiring behind the front bumper on my 1986 Convertible, the 15amp courtesy light fuse is no longer blowing. The under hood lights are on the same circuit and the loom going to them was burnt and corroded. Good news! However, I still have a voltage draw at that fuse. With the fuse removed, I still get the test light lighting up and still showing voltage draw at the battery. Does anyone know if this is normal?

Hot Rod Roy

3. The antenna relay DOES have power all the time. That's the only way the antenna can go down after you turn off the ignition.

7. Do your horns work if you power them directly from the battery?

The residual current draw from the battery should be less than 50 mA, after the courtesy lights go off.