1987 wiring help

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purple charlie

CCCUK Member
Im used to working on the WWW (Weird and wonderful wiring) mainly on old bikes but the Vette has confused me.
Ive only had the car a couple of weeks and getting ready for the MOT.
Initially, the side lights and marker lights were working, the LH headlamp was loose, I repaired the bezel, then the RH hi beam went. After various rusty problems, the bezels and headlamp bulbs now work.. BUT, the side/park lights and side marker lights have stopped.

Secondly, the door mirrors do not move.
Thirdly, the radio does not work and the tools Ive got will not remove (Pioneer) (my problem) (thinking radio has a fuse)
Fourth the inside vanity mirrors dont light.
Fifth the screen washers dont work.

Ive checked the fuses as in the owners handbook, apart from the sidelights working that now dont, the rest have not worked since I got the car.
I know 1970's Harleys used resetable fuses but looking at Haynes I cant see a common feed to solve all.
cant see a feed for the vanity mirrors or door mirrors.

any thing I should look for first before I start pulling wires about? thanks
 
Steven Smith

Steven Smith

CCCUK Member
purple charlie said:
Im used to working on the WWW (Weird and wonderful wiring) mainly on old bikes but the Vette has confused me.
Ive only had the car a couple of weeks and getting ready for the MOT.
Initially, the side lights and marker lights were working, the LH headlamp was loose, I repaired the bezel, then the RH hi beam went. After various rusty problems, the bezels and headlamp bulbs now work.. BUT, the side/park lights and side marker lights have stopped.

Secondly, the door mirrors do not move.
Thirdly, the radio does not work and the tools Ive got will not remove (Pioneer) (my problem) (thinking radio has a fuse)
Fourth the inside vanity mirrors dont light.
Fifth the screen washers dont work.

Ive checked the fuses as in the owners handbook, apart from the sidelights working that now dont, the rest have not worked since I got the car.
I know 1970's Harleys used resetable fuses but looking at Haynes I cant see a common feed to solve all.
cant see a feed for the vanity mirrors or door mirrors.

any thing I should look for first before I start pulling wires about? thanks
Click to expand...
The side lights, do you mean the front fog lights or the lights just in front of the wheels ?
If both mirrors don't adjust I would look at the rocker switch that selects between sides as if this fails they both stop working.
Check the fusable links, on the jump start post behind the battery, this is the main power distribution point. It gets wet due to the hood catch drain hole being right above it. Clean and test all the wiring here first, as a bad connection here can cause lots of electrical issues.
 
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purple charlie

CCCUK Member
thanks for the replies,
the side lights are the small bulbs in the headlights, the H4 bulbs are main and dip.
the marker lights being the ones on the sides by the wheels.
knowing American bikes, I thought there may be a fuseable link somewhere, it was just getting around to finding it.

it was just strange they all worked before I had to play with the bezels that hold the headlights in.

presumably the original washer pump is on the bottom or side of the reservoir? the car has a remote after market one fitted so thats the next thing for the mot.
 
Steven Smith

Steven Smith

CCCUK Member
purple charlie said:
thanks for the replies,
the side lights are the small bulbs in the headlights, the H4 bulbs are main and dip.
the marker lights being the ones on the sides by the wheels.
knowing American bikes, I thought there may be a fuseable link somewhere, it was just getting around to finding it.

it was just strange they all worked before I had to play with the bezels that hold the headlights in.

presumably the original washer pump is on the bottom or side of the reservoir? the car has a remote after market one fitted so thats the next thing for the mot.
Click to expand...
The small bulbs in the headlights are not standard so someone has added them and there will be no wiring diagram to help.
 
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purple charlie

CCCUK Member
Ok thanks, both are Euro standard uk legal parts so thought were straight swap. Both were working, so have to wait til it dries up to have another look.
 
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purple charlie

CCCUK Member
update on the situation...
I now have sidelights again.
I think the problem is the fuse board. the lights will go off if moved and the engine will die if another fuse is wiggled.
Is there a way of removing the fuseboard? there are pop rivets, would drilling these out allow access to the back and wiring or does it mean removing the whole dash cover?
still have no radio , moving door mirrors or washer motor working so hoping its a loose wire to the fuseboard.
 
teamzr1

teamzr1

Supporting vendor
Looking at your fusebox and the circuits you're having problems with, I think you are correct is
the problem being the circuits connected to the bus

Could be in moving the box itself may cause even more circuits having a problem and if not fixable have to replace it

charm.jpg
 
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purple charlie

CCCUK Member
the dash has stopped displaying now, so I really need to get the fuse board out to see if there is a crack in it or just dry joints,
having to get back out and walk around , job for another day as working outside.
so, back to question, how to get it out
 
Steven Smith

Steven Smith

CCCUK Member
purple charlie said:
the dash has stopped displaying now, so I really need to get the fuse board out to see if there is a crack in it or just dry joints,
having to get back out and walk around , job for another day as working outside.
so, back to question, how to get it
Click to expand...
I have previously had the dash pad off for another issue but couldn't see the back of the fuse board.
I can only assume, dash pad, bread box and hush panel have to be removed for access to it.
 
teamzr1

teamzr1

Supporting vendor
Confusing as to searching internet as to aux fuse box as in 1990 GM changed the dash electronics and in doing so moved the aux fuse box to the end of the right end of dash

Pre-1990 C4s, searching if correct

Behind the DIC (drivers information cluster) there is a fuse block.
You have to remove the radio/climate control bezel. 4 or so screws hold it on.
Once that is removed you need to remove the DIC and you should be able to see what you need.

The fuse block has a front and back.
Remove center bolt to separate.
Unbolt fuse block, gently open the fuse block halves by separating the outside tabs.
 
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purple charlie

CCCUK Member
the car is a 1987, the hand book shows the same fuse layout picture as you posted above and its on the right/passengers side of the dash, accessible only with the door open.
You mention in the first line GMC changed the location in 1990
Confusing as to searching internet as to aux fuse box as in 1990 GM changed the dash electronics and in doing so moved the aux fuse box to the end of the right end of dash
that is where mine is, could it have been a later retro fit?
will check the vin and build numbers now. vin decoder confirms 1987 and the owners book also shows on the side so standard for a 1987
 
Last edited:
Steven Smith

Steven Smith

CCCUK Member
purple charlie said:
the car is a 1987, the hand book shows the same fuse layout picture as you posted above and its on the right/passengers side of the dash, accessible only with the door open.
You mention in the first line GMC changed the location in 1990
Confusing as to searching internet as to aux fuse box as in 1990 GM changed the dash electronics and in doing so moved the aux fuse box to the end of the right end of dash
that is where mine is, could it have been a later retro fit?
will check the vin and build numbers now.
Click to expand...
I have an 86 and there is a small fuse box behind the center display.
There are 3 fuses there, the hatch fuse, anti theft fuse and injector fuse.
There is also the hazard light relay, horn relay and the start relay.
There is also the module that control the bell tone, for when you leave the key in the ignition switch.
 
Steven Smith

Steven Smith

CCCUK Member
Here is a really useful C4 "cutaway" series that shows where most things are hidden.
youtube.com

C4 Videos

Watch our collection of performance, repair and restoration videos including DIY and unboxing for 1984-1996 Corvette parts.
youtube.com youtube.com
 
teamzr1

teamzr1

Supporting vendor
purple charlie said:
the car is a 1987, the hand book shows the same fuse layout picture as you posted above and its on the right/passengers side of the dash, accessible only with the door open.
You mention in the first line GMC changed the location in 1990
Confusing as to searching internet as to aux fuse box as in 1990 GM changed the dash electronics and in doing so moved the aux fuse box to the end of the right end of dash
that is where mine is, could it have been a later retro fit?
will check the vin and build numbers now. vin decoder confirms 1987
Click to expand...

Was mentioning the aux fuse box location for 1987
Where in 1990 the instrument panel for 1990 was redesigned as a "hybrid," combining a digital speedometer with analog tachometer and secondary gauges and changes to all fuse locations

So your looking to work on the fuse box located at the end of dash by passenger a pillar
If you take the knee panel off, would that allow than to get to the back side of the fusee panel ?

fusebox.jpg
 
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purple charlie

CCCUK Member
teamzr1 said:
Was mentioning the aux fuse box location for 1987
Where in 1990 the instrument panel for 1990 was redesigned as a "hybrid," combining a digital speedometer with analog tachometer and secondary gauges and changes to all fuse locations

So your looking to work on the fuse box located at the end of dash by passenger a pillar
If you take the knee panel off, would that allow than to get to the back side of the fusee panel ?

View attachment 31928
Click to expand...
yes similar but the screw to release the cover is the other end down towards the pillar. need to clear and reposition so I can get the door wide open. big pad (air bag?) on the fascia face
 
teamzr1

teamzr1

Supporting vendor
purple charlie said:
yes similar but the screw to release the cover is the other end down towards the pillar. need to clear and reposition so I can get the door wide open. big pad (air bag?) on the fascia face
Click to expand...

You mean someone installed the cover flipped, so the screw is by the A-Pillar ?

fuseboxs.jpg
 
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