87 Corvette....118K miles...
I'm having a problem with brake lights and backup lights not working.
I've checked the obvious --- bulbs, fuses, etc., and now at a loss as
to what could cause this problem.
Could this be a switch problem? Although I'm not aware of any switch
that would control these functions, perhaps someone has experienced
Any help would be appreciated.
I agree with Bob. Most likely a grounding issue. On my '89, the ground
path for backup and stoplight circuits is through Connector C403, RH
Cargo compartment aft of the right wheelhouse. That connector also
carries the grounds for the license plate light -- however three black
wires are involved. If license plate light is working then it's
probably the ground wire for the BU & Stop/Turn.
The actual frame ground point for these circuits (forward side of C403)
is ground point # G401.
For the Convertible, G401 is located on the RH side of the cargo
compartment behind the passenger seat.
For the Coupe, G401 is located in the mid-center of the lock pillar.
There are other things grounded at G401: Hatch release, Bow releases,
Antenna Relay, Fuel Level Sensor, and the turn signals. If those are
working, the ground is probably intact and the problem is a black ground
wire aft of C403. (Fuel sensor and license plate light also return
grounds through connector C403).
The rear electrical for the '89 and the '87 should be "close" but if you
have access to a FSM, checking the actual ground paths would be a smart
Hope this helps. Let us know how you make out.
Thank you for this valuable information...and I apolgize for the delay
I did locate the wires mentioned - checked the connections as best I
could but other than that, I'm now at a loss as to the method of
fixing the problem. Perhaps you can gather that I'm not too
technically inclinded at times.
I also took your advice and ordered the FSM from Helms...something I
planned to do some time ago...thanks for the push!
Will update [timely] after the manual arrives. Again, thanks for your
quick response and info.
Just a few thoughts I had --
looking at a fuse doesn't sometimes tell, you have to check the continuity
with a multimeter, if you don't have one I've seen them as cheap as $4.99.
Same goes with a bulb you have to test it, but all bulbs out at the same
time, with the backups, wouldn't be the problem this time though. Use ohm
scale on the meter here. Putting a new fuse in might be the thing to do
just in case. I'd check with the meter both sides of the fuse holder too,
one side should have 12v just touch each side with a probe and the other
probe to a ground maybe the fuse isn't getting power. Put the meter on DC
volts for this one.
You can check the ground at the bulb housing with a meter too, just poke in
a probe touching the side of the housing and touch something metal with the
other probe with the meter set on ohms. Probably the frame would be a good
part to touch, not something like the license plate you need something that
connects to the frame and has bare metal not painted or rusty/dirty where
you touch it.
Are you sure the brake and backups quit at the same time? Maybe they are
separate problems -- backups sometime go because of the switch on the
tranny, and the brake lights because of the switch on the brake pedal.
Switches are the problems many times as they have parts that wear and get
dirty, even a boot toe hitting the brake switch can destroy it, and the
backup switch, if on the tranny, gets dirty and has to endure heat and
Hope this helps!
'96 LT-4 CE
On my '89, the 'hot' side of both of these
circuits goes through the hazard flasher
Not a good place to start with since it
involves the forward harnesses and the
strering column. But if you've eliminated
Good move getting the FSM -- that will help a
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