1995 Saturn SL1 reverse/back-up lights & switch

Car: 1995 Saturn SL1 SOHC.

Symptom: Both reverse/back-up lights do not turn on when in reverse gear.


My troubleshooting: From reading my Haynes manual.... I located the
Back-up Light Switch on top of the manual transaxle.
1. The Back-up Light fuse is good.
2. Bulbs test fine.
3. There is circuit continuity between Back-up Light fuse (at front
engine fuse box) and lamps and also from the Back-up Light fuse and the
right contact of the switch plug (view w/ clip @ top).
4. With ignition ON (engine not running) I read 12.7V at the right
terminal of the Back-up Light fuse. In this state I read only 60mV at
the right contact of the switch plug and the lamp terminal with the bulb
removed.
5. Wires and Wire-harness look in good shape.

From the circuit diagram I should be reading Voltage on the battery
side of the switch connector, then also on the ground side of the switch
when in reverse if the switch is good. Right now it seems that I cannot
conclude that the switch is bad by testing it properly.


*from a suggestion on another forum....
With ignition key OFF, I unplugged the 2-wire connector from the switch,
closed (short w/ wire) the circuit on both terminals of the
connector.... turned ON ignition key.... still no light, also ran
engine.... still no light.


Any thoughts? Thanks very much for your assistance, much appreciated.
Cheers, Roger

Its just possibile that you have a bad section of wire! I have a 93 sl2
that had a 3 foot section of wire that went to a rear abs unit. the wire
looked fine from outside but tested bad for continuity, I scraped the
insulation off the wire and the stranded wire inside had turned to a
corroded powder.

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"Roger E" > wrote in message
...
> Car: 1995 Saturn SL1 SOHC.
>
> Symptom: Both reverse/back-up lights do not turn on when in reverse gear.
>
>
> My troubleshooting: From reading my Haynes manual.... I located the
> Back-up Light Switch on top of the manual transaxle.
> 1. The Back-up Light fuse is good.
> 2. Bulbs test fine.
> 3. There is circuit continuity between Back-up Light fuse (at front engine
> fuse box) and lamps and also from the Back-up Light fuse and the right
> contact of the switch plug (view w/ clip @ top).
> 4. With ignition ON (engine not running) I read 12.7V at the right
> terminal of the Back-up Light fuse. In this state I read only 60mV at the
> right contact of the switch plug and the lamp terminal with the bulb
> removed.
> 5. Wires and Wire-harness look in good shape.
>
> From the circuit diagram I should be reading Voltage on the battery side
> of the switch connector, then also on the ground side of the switch when
> in reverse if the switch is good. Right now it seems that I cannot
> conclude that the switch is bad by testing it properly.
>
>
> *from a suggestion on another forum....
> With ignition key OFF, I unplugged the 2-wire connector from the switch,
> closed (short w/ wire) the circuit on both terminals of the connector....
> turned ON ignition key.... still no light, also ran engine.... still no
> light.
>
>
> Any thoughts? Thanks very much for your assistance, much appreciated.
> Cheers, Roger

Sounds like you are doing all the right diagnostics, I suspect your problem
is in the wiring between the fuse and the switch, my guess would be in or
near the switch connector. Wiggle the connector with the voltmeter
connected to see if you can get a connection inside a possibly broken wire.
In the old days we would probe the wire but today we realize that will allow
moisture to enter and corrode the wire and the wires are so thin they are
easily damaged, (save this test for last, but I suspect this will be the
only way you can verify the connection at the fuse and the wire itself.)

If you are sure of the correct side of the fuse connector then check the
resistance and continuity of the wire to the transmission switch with the
fuse removed. Also with the fuse removed you could jumper from the battery
hot side to the lamp side of the trans switch connector to check that the
lamps light correctly, if this test fails then I would suspect grounding
problems but would expect this to also cause problems with other tail
lights.

Good luck YMMV

Thanks Folks

When looking at front engine fuse box on the driver side (normal view &
fuse out) I do have continuity (0.00 ohms) from the right terminal of
the fuse socket to the lamps and also from this same point on the fuse
socket to the right terminal contact of the Back-up Light switch plug
(view w/ clip @ top). What is strange is that with the ignition on
RUN/ON (engine not running) I do have >12V at the right terminal of the
fuse socket but this voltage does not appear also at the other two
points of continuity mentioned above. This voltage should appear at all
3 points if the continuity shows this to be the same node
electrically.... there are no components on this portion of the
circuit... from the Haynes Manl, this looks like a simple circuit....
but measurements point to something faulty in the wiring. A tell sign is
that when I short the switch connector bypassing the switch I get no
light at all w/ the ignition on.

Thanks, Roger



Private wrote:
> "Roger E" > wrote in message
> ...
>> Car: 1995 Saturn SL1 SOHC.
>>
>> Symptom: Both reverse/back-up lights do not turn on when in reverse gear.
>>
>>
>> My troubleshooting: From reading my Haynes manual.... I located the
>> Back-up Light Switch on top of the manual transaxle.
>> 1. The Back-up Light fuse is good.
>> 2. Bulbs test fine.
>> 3. There is circuit continuity between Back-up Light fuse (at front engine
>> fuse box) and lamps and also from the Back-up Light fuse and the right
>> contact of the switch plug (view w/ clip @ top).
>> 4. With ignition ON (engine not running) I read 12.7V at the right
>> terminal of the Back-up Light fuse. In this state I read only 60mV at the
>> right contact of the switch plug and the lamp terminal with the bulb
>> removed.
>> 5. Wires and Wire-harness look in good shape.
>>
>> From the circuit diagram I should be reading Voltage on the battery side
>> of the switch connector, then also on the ground side of the switch when
>> in reverse if the switch is good. Right now it seems that I cannot
>> conclude that the switch is bad by testing it properly.
>>
>>
>> *from a suggestion on another forum....
>> With ignition key OFF, I unplugged the 2-wire connector from the switch,
>> closed (short w/ wire) the circuit on both terminals of the connector....
>> turned ON ignition key.... still no light, also ran engine.... still no
>> light.
>>
>>
>> Any thoughts? Thanks very much for your assistance, much appreciated.
>> Cheers, Roger
>
> Sounds like you are doing all the right diagnostics, I suspect your problem
> is in the wiring between the fuse and the switch, my guess would be in or
> near the switch connector. Wiggle the connector with the voltmeter
> connected to see if you can get a connection inside a possibly broken wire.
> In the old days we would probe the wire but today we realize that will allow
> moisture to enter and corrode the wire and the wires are so thin they are
> easily damaged, (save this test for last, but I suspect this will be the
> only way you can verify the connection at the fuse and the wire itself.)
>
> If you are sure of the correct side of the fuse connector then check the
> resistance and continuity of the wire to the transmission switch with the
> fuse removed. Also with the fuse removed you could jumper from the battery
> hot side to the lamp side of the trans switch connector to check that the
> lamps light correctly, if this test fails then I would suspect grounding
> problems but would expect this to also cause problems with other tail
> lights.
>
> Good luck YMMV
>
>

"Dev Null" > wrote in message
...
> Hello,
>
> I would like to ask you a question offline.
>
> If you don't mind, please send me an email at (rot-13)
>
>
>
> Thank you

With respect, I am sure you will understand my hesitation, but I do not have
any online or other relationship with you. Could you give me a hint or some
other motivation?

I do after all try to be Private.