Topic: electrical
in Forum: C3 Electrical
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Good morning Folks:
I have a wild question.
I brought our '81 into (2) very respected shops. The 1st one repaired the A/C blower and Alternator issue, but reported that there was an internal short draining the battery and he did not want to address it.
The second shop dignosed the drain as the power antennae relay was cut out and hard wired to the courtesy light circuit. We replaced the relay, the radio works for me except it cuts out when you apply the brakes and comes back on when you let them off. He stated that the radio fuse was blowing when I picked it up and the A/C blower again is not working. It appears obvious that the radio is wired to another circuit if it works but if fuse is blowing. I checked the fuse and it is not blown?????
I am getting ready to do major work on the vehicle and would like to give him more direction after I complete my work and bring back to him. Has anyone ever had this problem before?
Thanks,
Gurtz
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Duncanville, TX - USA
Joined: 11/8/2003
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Yeppers...that IS a wild one there! 
I can check the wiring diagram when I get home from werk this eve., and see if I can come up with anything. It sounds like "Bubba" has been at werk on this one!
Does this car have cruiz control?
I can check the wiring diagram when I get home from werk this eve., and see if I can come up with anything. It sounds like "Bubba" has been at werk on this one!
Does this car have cruiz control?
Joel Adams
C3VR Lifetime Member #56 
My Link 
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
strange situation... but that seems normal with corvette :)
first where i would look for the problem with the radio is around the brake pedal... maybe when pushing the brakes it pushes on a wire ?? or maybe the radio is connected to the wiring of the brakelights somehow ?
anyway.. you need a wiring diagram and follow the circuit with a multimeter , check the resistance to find where the problem is
goodluck
art-corvette
Pull the center console and determine where the radio is wired for
power. It sounds like someone has spliced into the brake light circuit
to get power to the radio. I have also seen people pull power from the
fuse box on the brake light circuit. The radio requires a minimum
voltage to work properly and when that voltage is dropped, even for a
moment, the radio quits until the voltage returns to normal.
Scott
Scott
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
The diagram shows the radio and the cruiz control share a common feed from the fuse box, tho it is NOT the same fuse. It also shows the anti-theft control module as a power source for at least part of the radio(yellow wire), possibly only a light, as most(but not all) yellow wires indicate a lamp circuit.
I would check to see where the actual power feed to the radio is coming from, as has been suggested. Also, is this the factory original radio, or has it been swapped out somewhere down the line?
If you would like a copy of the wiring diagram, shoot me a P/M with an e-mail address, and I'll send it to ya.
I would check to see where the actual power feed to the radio is coming from, as has been suggested. Also, is this the factory original radio, or has it been swapped out somewhere down the line?
If you would like a copy of the wiring diagram, shoot me a P/M with an e-mail address, and I'll send it to ya.
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
I appreciate everyone' replies.
Yes Joel, it is a cruise control vehicle that is not working and I don't think the anti theft device is working either. Bubba definitely got ahold of this one. I have the GM manual, Lectric Limited and the Haynes schematics. Do you have something different? If so, my email address is gurtz@eatel.net.
Thanks,
Rick
Lifetime MemberHOWELL, NJ - USA
Joined: 5/18/2004
Posts: 6812
Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
In the worst case, you could tap into an available ignition port on the fuse block and connect to the radio's postive power wire.
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Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Rick, if you have the factory service manual, you have a good diagram already.
The ones I have are Mitchel l...good, but not quite as complete on some systems as the originals.Adams' Apple 2006-11-20 20:56:42
The ones I have are Mitchel l...good, but not quite as complete on some systems as the originals.
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
To Luke and Joel:
It turns out the yellow power wire from the radio is connected to the very bottom left hand port not the radio fuse location in the panel and it is a straight run not hitting anything. As a matter of fact, I replaced it with a new wire to rule out knicks, etc.
Sorry I have not gotten back till now but am swapping motor, changing out heater core, etc. Been a bit busy. Is that lower left hand port under the fan fuse the ignition port you were speaking of?
Thanks,
Gurtz
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
If the terminal is marked as "IGN", then yes. The fuse box normally will have a few extra terminals in it for additional, "optional" equipment. Some are marked "BATT", for full time voltage, and some are marked "IGN", for power only with the key on.
If the radio fuse is blowing, but the radio is powered by a different circuit, then the radio is not causing the fuse to blow.
Check the yellow wire closely...most times, a yellow wire is used for lighting, not to power a component. The lower "port" you are speaking of may be for the radio light itself.
There are a couple of pics of fuse boxes on one of the forums here...I'll look and see if they are still up...
The lower left in this pic IS for "lamps"
Adams' Apple 2006-11-20 21:11:58
If the radio fuse is blowing, but the radio is powered by a different circuit, then the radio is not causing the fuse to blow.
Check the yellow wire closely...most times, a yellow wire is used for lighting, not to power a component. The lower "port" you are speaking of may be for the radio light itself.
There are a couple of pics of fuse boxes on one of the forums here...I'll look and see if they are still up...
The lower left in this pic IS for "lamps"
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
in Forum: C3 Electrical
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