Backup light not working

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hugofant
Posts: 23
Joined: Mon Jul 17, 2017 2:24 am

Backup light not working

Post by hugofant »

Hello,
today i've tried to fix my non working backup light...without success....Seems that i've two problems in parallel and maybe somebody can give me additional information.
the situation: car is 4 speed man transmission, previous owner has cut the cable to the switch and twisted together again (plus isulating tape).
what i've done: opened the cable connections, put "plus" on one side --> lights are on. connected this side to the switch again and put plus one the other side of the switch --> with reverse gear in, lights of.......my conclusion: switch not working and has to be replaced

but, when bypassing the switch (connecting the two cables (going to the connector in the tunnel) thw lights are still not working. After checking, there is no "plus"....and here's my problem: i don't understand the wiring diagram. thin green can be trailed till the large connector under the dash. on the other side a thick light and a thick dark green is connected. Dark green should go to the fusebox, but can't see it there, to which fuse should it be connected?

a hint would be appreciated ;-)

thanks in advance and best regards
Roman
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bbodie52
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Re: Backup light not working

Post by bbodie52 »

According to the shop manual, the heater fan and backup lights are both supported by the same 20 amp fuse. It is the third fuse in the fuse block. Did you check the fuse to ensure that it has not failed?

Troubleshooting the circuit should be fairly straightforward. Do you have access to a multimeter to test the circuit? You should be able to test the backup light switch function at the transmission, using a multimeter to measure continuity (ohms). With the backup light switch disconnected from the circuit, you should read an OPEN condition between the two terminals of the backup light switch with the transmission NOT in reverse. If you shift the transmission into the reverse gear, you should have continuity between the two electrical terminals of the switch (switch CLOSED). If the switch does not show electrical continuity through it when the transmission is in REVERSE, the switch has failed and needs to be replaced.

I believe the ignition key needs to be in the ON position for power to be applied to the circuit. With the key ON, you should be able to measure 12 V DC between the voltage lead in the tunnel under the car and GROUND. If you measure voltage present on that wire, the backup lights should illuminate if you connect the other lead in the harness to the voltage lead. If the backup lights illuminate properly when you connect the two wires together you have proven electrical continuity from the fuse block to the backup lights. You only need to add a functioning backup light switch to the circuit to reestablish the backup lights function in your Corvair.

Left-click the image below to enlarge for better viewing. Left-click a second time for maximum enlargement…
1963 Corvair Passenger Car Combined Schematic
1963 Corvair Passenger Car Combined Schematic
EM Corvair Fuse Block
EM Corvair Fuse Block
If your backup light switch has failed you have two options. Clark's Corvair Parts offers a replacement switch that can be installed in the transmission to reestablish a working backup light circuit. Alternately, you may choose to use the three speed transmission backup light switch as a substitute for the switch is installed in a four speed transmission. The three speed transmission switch is physically located in the tunnel and utilizes the moving shift linkage in the tunnel to close the switch. The three speed switch option is labeled "fix-it kit" in the center of the catalog page shown below.

ImageImage
:link: http://www.corvair.com/user-cgi/catalog ... N&page=84B
Image

Part number C5364: 61-65 4SP BACK-UP SWITCH *EXACT REPRO BOOT & GASKET (C383A) INCLUDED

Weight: 0 lbs 10 oz
Catalog Pages(s): 84B
Price: $ 53.50


Image

Part number C8379: 4 SPEED BACK UP SWITCH FIX-THEY LEAVE OLD SWITCH IN PLACE-THIS WORKS OFF SHIFT ROD

Weight: 1 lbs 0 oz
Catalog Pages(s): 84B
Price: $ 39.05
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible
hugofant
Posts: 23
Joined: Mon Jul 17, 2017 2:24 am

Re: Backup light not working

Post by hugofant »

Hi Brad,
thnx for your detailed answer....and in the meantime i was able to located the problem(s).
Fuse was ok (checked and heater's working), but multimeter showed that 12V DC is not going through connector under the dash. I was able to fix that with cleaning contacts. Connector in the tunnel hat the same problem and now it's getting a bit "strange". The cable from the connector to the switch looked completely ok (no physical damages), but multimeter showed, that 12V DC are going in, but on the other side only 3V DC were coming out (with no switch attached). So i've also renewed the cable and lights are working now, when bypassing the switch.
Regaring replacement of the switch: i'm already in contact with Clark's, but actually i'm not sure, which solution to take....but i'm tending torwards "fix it kit", cause there is no need draining/refilling transmission oil.

thanks for your help and best regards
Roman
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bbodie52
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Re: Backup light not working

Post by bbodie52 »

Removing the old switch from the transmission will only produce a few drips of fluid. The cost is similar with either solution, with the "fix-it kit" somewhat cheaper — enough savings to treat yourself to lunch at McDonald's after you finish and get your Corvair back on the ground. ::-):
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible
dave t
Posts: 138
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Re: Backup light not working

Post by dave t »

I had a problem with my backup lights staying on in all gears. I added another gasket/washer on the switch and that fixed it. It was a Clark's repro switch, 1964 4-speed trans. I lost about a third of a cup of trans oil while quickly pulling and replacing the switch. About 3 pumps from an oil bottle fixed that.

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rfw66
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Re: Backup light not working

Post by rfw66 »

I had the same problem as dave t, but.... on a 65 Corsa. I had purchased a repro from Clarks but ended up repairing the contacts on the old switch. Soldering on new contacts and using the boot off of the repro switch! Works great


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Bob W
65 Corsa convertible
68 Monza coupe
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