“Vacuum Actuated Headlamp Doors”
1969 RPO Z22
Brief History:
All three years of the first generation Camaro were
available with the RPO Z22 “Rally Sport” option. Any Camaro could be ordered
with the desirable “hidden headlights” starting with the most modest inline 6
cylinder right on up the food chain to the powerful COPO. In 1967 the headlight
doors were opened and closed by electric motors, which Chevrolet quickly
replaced with a vacuum actuated system in 1968. I do not know if the 1968
system was revised in 1969. This means if you have a ’68 RS Camaro use this information
cautiously and have the correct year manuals referenced below to be sure...
Reference Material:
The Vacuum actuated headlight doors are just one of the
features included on the 1969 (RPO Z22) Rally Sport Camaro. The intent of this
tech feature is to aid you in understanding how this very simple vacuum
circuitry is plumbed and works. Please reference the ‘1969 Camaro Factory
Assembly Instruction Manual’ (AIM) RPO Z22 B6 (page 462) for part numbers and
proper installation of hardware and routing of hoses.
The diagram I have included has been laid out in a way that
depicts proper connections of hoses and components based on the AIM and will
give you a feel for where everything belongs. They are not intended to show
mounting and proper physical placement. For additional reference, the 1969
Chevrolet ‘Chassis Service Manual’ (CSM) also has information that may be of
assistance to you (Section 12: Electrical-Body and Chassis: Lighting Systems
starting on page 12-6 ‘Vacuum Operated Headlamp Service’).
Getting Started:
Take a good look at the diagram; let’s start with the vacuum
source. You will find a vacuum line running from a fitting on the intake
manifold across the firewall toward the driver side fender (the black hoses on
the diagram).
Note: Hoses are black or black with colored stripes and
are as depicted in the AIM. These colors concur with the CSM with the exception
of one of the black hoses, which is shown with a white stripe. I chose to
default to the AIM for correctness as the CSM represents several of the
Chevrolet line up with hidden headlights.
With the engine running, the headlights off and the override
switch in the normal position there will be vacuum present on the black hoses,
the yellow-striped hoses, the ‘Vacuum Tank’ and the middle port of the ‘Vacuum
Relay’. You will also find vacuum present through the headlight switch and on
the orange-striped hose from the headlight switch to the ‘Vacuum Relay’ and the
green-striped hoses to the actuators. The doors will be closed under these
conditions.
Take note of the one way check valve or "Vacuum Line
Filter" (much like the one used in the power brake booster system) placed
in the main vacuum line coming from the intake manifold. It keeps the system
(black, orange, yellow and green-striped hoses) holding about 10" of
vacuum when the engine is shut off. That is based on what I measured on my own
system. At this point there is no vacuum present on the red-striped hoses.
The Operation:
The headlight doors operate (open) when the headlight switch
is pulled out to the second position (headlights on) cutting off the vacuum to
the orange-striped hose. This operates the ‘Vacuum Relay’ removing vacuum from
the green-striped hoses and placing vacuum on the red-striped hoses to the
actuators. This can also be accomplished by operating the over ride switch
(pushing in the plunger) which plugs the orange-striped hose, removing vacuum
at that point (same result as turning on the headlights).
Testing:
To test the system, start the engine and push the override
plunger switch in on the ‘Vacuum Relay’, the doors should open. Pull out the
plunger on the override and the doors should close. Do the same from the
headlight switch. If they don’t open and close properly, or at all, make sure
the mechanical parts of the doors are adjusted and working smoothly before
tearing into the plumbing.
Assuming the mechanical parts all function properly you now
know where vacuum should be under open and closed conditions. Trouble shoot by
unplugging one hose at a time and verifying that vacuum is present or not.
Reproduction actuators have had a bad rap in the past so you might want to
start there. Verify the switches (Headlight and Vacuum Relay) are doing what
they are supposed to as well. Hose kits have been known to have the ends get
brittle and crack before they even get taken out of the box they are packed in
so be alert for vacuum leaks too. If low idle vacuum is a concern, vacuum
should increase with rpm so set your idle up a bit if you have to for testing.
End Results:
It’s a great feeling knowing your headlight doors open and
close properly, it's the little pleasures in life, isn't it? Special thanks go
out to Team Members Chad Renfro (CA420) and Todd Bradford (DTB) whose research
and willingness to share their knowledge with TC has assisted me greatly with
this tech reference page. Thanks guys!
copyright © DjD 2003
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