1985 Pontiac Fiero GT - Backup Lights not working - Could it be backup light/neutral switch?

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eg@elkinsys33.com - 18 Dec 2003 22:19 GMT

Both backup lights on my 1985 Fiero GT are not lighting up when the car is
in reverse. The car has an automatic transmission and a "backup
light/neutral switch" mounted on the transmission where the transmission
shift cable mounts to the transmission.

The brake light bulbs are fine and the shifting mechanism is working
properly, with there appearing to be no play at the switch linkage on the
transmission or other visible defect. As is normal, the car starts in Park
but not in Drive; and it will start in neutral. Everything shift-wise works
fine, but the backup lights don't come on when in Reverse.

All other rear end lights work properly.

I checked the connector that goes to the "backup light/neutral" switch (that
is what the Haynes manual calls it), and I cleaned up the connectors on the
cable and removed corrosion. I did not remove the backup light/neutral
switch itself to clean its contacts, however.

I am wondering whether I should simply buy a new backup light/neutral
switch, or whether it is worth first removing the switch to clean its
contacts before buying a new switch.

Is there a diagnostic one can do to determine if the switch is at fault
without removing it? Perhaps there are leads on the cable going to the
backup light/neutral switch that should be energized when the car is in
Reverse that I could check with my multimeter?

Any assistance offered will be appreciated.

Thanks.

Keith E. Risler

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Hank - 19 Dec 2003 00:43 GMT

If you have an ohm meter, disconnect the connection to the switch and
put the meter across the switch. it should have very low resistance 1
or 2 ohms max make sure the shifter is in reverse and the parking
brake applied. If it shows an open then the switch is bad. On my 85
manual 5 speed I had the same problem the switch is not repairable I
had to purchase a new one. I beleive I got it at a bone yard for a
buck it was a few years ago. If yo dont have a meter disconnect the
connector going to the switch and short the 2 wires together that go
to the lights not the switch end with a 18 guage wire then put the
shifter in reverse and the ignition key in the on position and see if
the lights come on. If they do put the shiffter back in park and
remove the jumper wire. If the lights came on yes the switch is bad. I
would not put the jumper wire on or off with the shifter in reverse as
the lights draw quite a bit of current. Don't let the any bare wire
from the jumper wire touch any metal part of the car.

Hope this helps.
Hank
85 2m4 170K

>Both backup lights on my 1985 Fiero GT are not lighting up when the car is
>in reverse. The car has an automatic transmission and a "backup
[quoted text clipped - 28 lines]
>
>Keith E. Risler

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eg@elkinsys33.com - 20 Dec 2003 01:24 GMT

Thanks for the information. Indeed it was the switch. I replaced it with a
new AC Delco switch ($49.00 Canadian dollars, here in London, Ontario,
Canada). The connector socket on the new switch was packed solid with
grease, so I presume the integrity of the switch connections is considered
important.

I opened of the old switch and found it was full of dirt and grime; it's an
amusing contraption consisting of metal traces that an internal arm sweeps
over to open and close various circuits.

The grease on the connector socket area of the connector was so abundant
that it was hard fitting the wring harness connector into it; if I were
doing it again I would have removed a little of the grease first.

Keith E. Risler

> If you have an ohm meter, disconnect the connection to the switch and
> put the meter across the switch. it should have very low resistance 1
[quoted text clipped - 15 lines]
> Hank
> 85 2m4 170K

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