***No Backup Lights***

[B-Co Kid]

I recently replaced the bulbs in the rear (brake and backup). My brake lights work fine, but when i put the b-co in reverse, the backup

lamps are not coming on. Im not really sure if they were coming on before changing the bulbs, but i do know at some point in the past they

were working. the bulbs were corroded and twisted apart when i removed them. Ive read on other topics about how to narrow down the problem, but

i am confused. i did a voltage check with the positive probe in the center of the socket and the negative probe on the body while the vehicle was in

reverse. the voltage reading was roughly 12.8-13.0v on the right and left sockets. does this mean the ground is bad, or is it suppose to read 12v? other topics say check the neutral safety switch. not sure how to check if that is the problem or not. any help is appreciated

 

[Krafty]

if the socket is reading 12 volts and the lights are not working then you are correct that they are not grounding properly. the comment about the safety switch is in regards of the wiring in the transmission, the reverse lights and safety switch both run out of the trans together so if one wasn't working then it may be adversely affected by the other. but that is not the case because you already discovered the ground issue.

 

[B-Co Kid]

thanks for the info krafty. where is the ground for the backup lights?? in another forum i read it was grounded to the sheet metal that is covered up by the brake light cover. there is a grounded wire there, but that ground wire is for the brake light socket. im sure i could trace the ground wire to the backup socket, but if you know where the ground wire is located, that would help alot. also, what should the voltage reading be at the backup socket with the b-co in reverse??

 

[Bully Bob]

"i did a voltage check with the positive probe in the center of the socket and the negative probe on the body.."

--This won't be accurate.--

Put your neg. meter probe on the bulb socket cup.

The ground eventually comes thru the socket cup itself.

You likely need to clean out those cups if they were that corroded.

I use limeaway & a Q-tip or an old toothbrush. Then rinse, wipe, & light oil.

Also., be careful not to short the pos. probe to the cup...that could blow the fuse.

 

[B-Co Kid]

My backup lamp sockets are made of plastic. how am i to put the negative probe on the cup?? i tried tracing all of the wires, and none of the wires are

frayed. im not sure how to check the ground wire. is it grounded to the body somewhere. from what i saw when i traced the wires, the ground wire ends at the plug, that plugs in to the nss. Is it possible for the nss to be bad, but still allow the b-co to start in park/neutral?? im stuck. PLEASE HELP!!

 

[BroncoJoe19]

The ground should be located on the bottom lip of the dash at the driver's left knee. Crazy... yeah I know /emoticons/[email protected] 2x" width="20" height="20" />

In case I am wrong there is also an important ground for the rear lights behind the left tailight assembly, somewhere.

 

[Bully Bob]

OOPS...! my bad..., :blush: forgot they went to plastic/plug-in in later yrs.

Joe's on top of it.... /

 

[B-Co Kid]

Ok I will search for the ground by the dash and post any findings. I stated earlier that there was a ground wire behind the tail light assembly and that it was for the brake lights. After unravelling the tape, that ground actually runs into the tailgate, so I'm sure it's for window motor/defrost etc. So one question, if I keep the black/pink wire attached to the socket, but ground the black wire to a different place (behind tail light assembly), will that work??

 

[miesk5]

yo, Yes

Find a good spot to clean & drill for self tap SS ***** or ss bolt.lock washer and nut

this is very close if not = to your yr.

G701 Behind IP near RH side of radio; G801 for both fuel pumps On LH inner fender behind headlights; G802 On RH inner fender behind headlights; G903 At LH side of rear crossmember; G909 at lower LH cowl access hole; G1003 On LH side of frame behind front crossmember; G1006 Rear LH side of frame at rear crossmember; G1303 at LH radiator support Locations in an 86 (see #5)

Source: by Seabronc (Fred W (Rosie) at Ford Bronco Zone Forums

and back-up lt troubleshooting and grnd/connector locations in an 89

http://broncozone.com/topic/21322-more-electrical-issues/page__gopid__111775entry111775

 

[B-Co Kid]

backup lights still not working. Ive replaced the backup light sockets and bulbs. that didnt work. (they were corroded and needed replacing anyway). I tested the circuit from the female connector that connects to the neutral safety switch rearward to backup lights, and there is continuity. i double checked the circuit with jumper wires to a battery, the reverse lights come on, so at least i know the problem is from the nss switch forward. i finally found the correct 6 pin nss switch, and installed the new one. reverse light still are not coming on. my final attempt at solving this thing was testing each pin of the nss switch for power when the ignition is on, but not started. there was 10V reading at the purple wire on nss switch (may be purple w/ orange stripe). the only thing i can conclude at this point is first, the problem is not the wiring to the backup lights after the nss switch, second, there is at least 10V getting to the switch, and third, i probably spent time and money on a nss switch that wasnt needed. the problem has to be in the wiring from nss switch forward, and that is a little more involved than my limited expertise allows me to solve. please help!

 

[miesk5]

yo,

Since you did have 12v at the sockets

this is about 99.999999% = to your 87;

Neutral Safety Switch (also referred to as Park/Neutral Position (PNP) & Back-Up Switch) Wiring Diagram (Partial) & Color Codes in an 89 5.8 C6; "...The lights in the back you are asking about are called Backup lights. A diagram of the circuit is attached. Do you have a volt meter? If you do, then turn the key to run and place the transmission in ® reverse. At the lamp socket check for 12 volts, (run a jumper lead all the way to the battery (-) rather than depending on the body metal for your ground). If you have 12V at the center contact in the light socket, you have ab ad ground. If you do not have 12 volts at the center contact of the light socket, go back to the Pink with black stripe wire at the transmission switch. If no 12 volts there check the other side of the switch (purple with orange stripe). I think you get the idea. When you get 12V the problem is between that point and the lamp socket. It could be either a corroded contact in a connector, a broken wire or the switch. I did not include the fuse because it also provides power for the turn signals..."

Source: by Seabronc (Rosie, Fred W) at Ford Bronco Zone Forums

 

[B-Co Kid]

FINALLY!!!

I figured out why the reverse lights werent working. The wiring harness that supplies power to the nss switch has a male and female connector located by the plastic fender well panel on the driver side. I tested both sides of the connector for continuity with my voltmeter. all wire to prong connections on the male and female sides of the connector had continuity except one. the purple with orange stripe. I cleaned the gunk of the small male prong and tested the one wire for continuity. It did after cleaning. I plugged the harness back up. plugged the nss switch back up. reverse lights work!! Hope this helps someone else.

 

[B-Co Kid]

FINALLY!!!

I figured out why the reverse lights werent working. The wiring harness that supplies power to the nss switch has a male and female connector located by the plastic fender well panel on the driver side. I tested both sides of the connector for continuity with my voltmeter. all wire to prong connections on the male and female sides of the connector had continuity except one. the purple with orange stripe. I cleaned the gunk of the small male prong and tested the one wire for continuity. It did after cleaning. I plugged the harness back up. plugged the nss switch back up. reverse lights work!! Hope this helps someone else.