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tail light, backup light, and neutral safety switch questions.

22153 Views 20 Replies 5 Participants Last post by  Spectre
my driver's side rear running light is not working. all other lights/features front and rear, both sides work.

I have no power coming INTO the bulb socket.

based upon a review of the wiring diagram ( ) it seems to me that other lights would be effected, if the trouble were upstream of the socket / where the wires for the socket tap into the main harness.

seems like a bad light socket to me. any other ideas?
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correction: additionally neither back up light works... back to the diagram :}
rear marker light now works.. coroded wire leading to it!

hoever the back up lights still don't work on either side. in the above refferenced link, there is a back-up light switch with BL/P wires running to the b/u lights.

my fuses are good.

where is this back up light switch? near the fuse box?

Neutral Safety And Back-up Light switch
This should be same:

Neutral Safety Switch Adjustment
Source: by Tim O (RED WAGON, redwagon) at FSB

Neutral Safety/Back-up Light Switch , Removal & Installation (under license from Delmar Publishers, comb of Chilton/Nichols/Delmar & Haynes); some may be incorrect, as reported by Seabronc, thanks Seabronc! NEW SITE URL!!! MUST REGISTER TO VIEW; select year, make, model, engine size and go to appropriate section
Source: by Chilton via Autozone

I was able to get into da Zone within 1 hour thanks to Comcast!
Here it is;
Select Instruments And Switches
Fig. 2: Later-type back-up light switch mounted on transmission

Automatic Transmission

See Figure 3

The switch is located on the left side of the transmission case. To remove:

Remove the downshift linkage rod return spring at the low-reverse servo cover.
Coat the outer lever attaching nut with penetrating oil. Remove the nut and lever.
Remove the 2 switch attaching bolts, disconnect the wiring at the connectors and remove the switch.

To install:
Install the switch on the transmission and install the two retaining bolts. With the transmission manual lever in the neutral position, check the position of the switch with a gauge pin (No. 43 drill) in the gauge pin holes.
Tighten the attaching bolts to 55-75 inch lbs.
Install the outer downshift lever and retaining nut and tighten the nut. Install the downshift linkage rod return spring between the lever and the retaining clip on the low reverse servo cover.
Connect the wire multiple connectors and check the operation of the switch.

Fig. 3: Neutral start/back-up light switch on vehicles with automatic transmissions
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gracias amigo!

i wasn't thinking it was that as the engine starts fine. i was thinking it was a sepp switch.

its about to rain i will check into it
it appears intact, and as stated, it does start in park.
to me, that seems to say its not the Neutral safety switch....right?
ok, check wiring next incl the connectors along the path from that NSS/Back-Up Light Switch.
Check that AutoZone Link for a wiring diagram.
Here is one from Steve83 that you can try;
Turn, Tail, Brake, Head Light, Hazard, Ignition Wiring Diagram for 84 Bronco & F-Series; "...Similar to 80-91 Bronco & F-Series..."

12 V @ Black/Pink (BLK/PNK)
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well it is sitting on the tranny, but its a single wire...much like i would gather from the diagram above (thx BTW). i guess newer BKOs have 4 adn 8 pin connectors there.. i was getting confusedeading other people's posts on newer trucks.

again its running, so i think, as you said, its a coroded wire down stream of the switch itself.
yw and glad you saved $ by DIY!
Can you take a pic of the switch/location so I can post it up in my site?
Was wire color the same as in Steve83's diagram? Black/Pink (BLK/PNK)?
i'll see if i can get a pic.

i am still confused. in reading the wiring diagram, the following colors are in place:
backup lit sw: BL/PNK (out) and PPL/GRN (in).

are we really sure the NSS and the backup light switch are the same thing??

thanks agian amigo :}
Now I am Wondering too! From what I have read from others in various Ford truck (F series & Bronco) Forums, they are the same switch. Now I am concerned that they are sepearte since your wiring colors are diff.
Time to ask others.
Will try later.

even the diagram has them both named differently, located sepparately (well for NSS, it just says "from NSS" and for bu lt switch it actually shows it) and colored differently.
what pic are you looking for? I have my engine/trans out right now.
i am trying to sort out a few things. My 82 with a C6 has a single wire going to it, as the only electrical connection to the tranny.

the diagram linked above (originally a Steve83 diagram) shows the NSS and back up lt switch as being different---different colors even.

However, in reading other posts, people are indicating the NSS and the Backup lt Switch are the same thing. Moreover, i have read that it is 4 pin/ 8 pin, depending upon the year, but never have i read single pin.

Lastly, the real source of this back up lights (bilaterally) don't work. However, i can start/run the BKO.
AAMCO rep on phone just said, ~"In a C6, the NSS and Back up light switch are the same thing... [and that] a failure of the NSS doesn't necessitate a NO START condition."

Perhpas it is the NSS.
yo M! Just missed ya here!

Last night around 0346 hours, I thought about it much better and am figuring the switch is ok, then there must be a wiring defect somewhere. The on-line AutoZone daigrams don't show your year Bronco, but the one for the 82 pick-up is same as Steve83's
BLK/PNK for 12v and BLK for Ground.

Ck the Ground, usually located at driver side of frame at rear crossmember
yep, agreed. I am not getting volts TO the plug. to me that means its upstream.

Given: there may be a concommitant failing ground, but power to, is the first step to ID.
You need to go back to your NSS. I have the same switch and there should be two wires. If the back up light section is bad and the NSS section is still good, the truck will still turn over. I know that theres two wires because I had to splice them together after my switch went bad to be able to fire my truck. Go back and look at the wriring on the switch, there's supposed to be two wires leading to a joint connector.
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