72 Mustang back-up lights not working

My back-up lights are not working. I have replaced the neutral switch. The bulbs are correct (1156) and new. The fuse is good. The tail lights all work. Please help !  

did you adjust the neutral switch???

on the 4 pin neutral safety switch wiring..
let me describe the 4 wires... and what they ***

colors to come later..
wire from the ignition switch from the Start position.. power ONLY in the cranking position..

wire to the starter solenoid S terminal..  this will only have power when the key is turned to the cranking position when the transmission is in park or neutral.....

thats half the switch..

a wire from the IGN 1 portion of the switch.. this will have power with the key in the RUN position.      

a wire to the back up lights..  this wire only will have power when the gear shift is in the REVERSE position...  its only a few degrees of rotation..

with the key on..  your foot on the brake pedal...    have somebody stand behind but slightly beside the car .. so you can see them in the side view mirror while you hold the brake pedal and slowly move the shift from park through reverse then through neutral through drive..

do the back up lights flash at all????

how are the grounds on the back up light bulbs???    do the bulb sockets come out of the housing???  if so..    take several feet if 16 or 18 gauge copper stranded wire..    strip the insulation off about 3 inches of one end..  remove the bulb..    create a tight loop of wire around the base of the glass part of the back up bulb.. then twist the bulb to tighten the grip of the loop of the wire..   then reinsert the bulb in the socket..   ground the other end of the wire under a known good ground.    see if the bulb works now..  when you move the gear shifter through reverse...

the back up light wire at the tail lights should be black with a pink stripe..

the solenoid wire colors on the harness side of the connector for the starting solenoid will be red and light blue stripe..

there is a 4th wire.. that might be purple on the 4 pin neutral safety switch connector that should have power when you turn the ignition switch turned on..  

Thanks waynep71222, you gave me alot of useful info. I have not adjusted the nuetral switch, it was installed at the trans shop that did the rebuild. The car starts in park and neutral. The back-up lights didn't work before the rebuild either. Should it need adjustment?
The lights did not flash at all with the car on, foot on brakes while moving through the gears.
I am heading out to check the ground now, I will check back when I finish that.


Nope still no lights with the ground wire jump ????  

if the Car starts in PARK and in NEUTRAL.. but not in any other gear..  the adjustment is correct..

just curious.. can you find the connector..

just curious.. do the windshield wipers work..    the power wire for the back up lights comes from the wiper fuse..  across the wiper switch  then forward to the neutral safety switch connector..

can you reach the 4 pin connector that leads down to the transmission.. its usually right at the firewall...

do you have key ON power on the white and purple wire or purple and white wire..

the wiring to the back is probably black and pink.. .

this is what a later version looks like...   your probably has a rubber bullet connector...

with 3 facing one way.. and one facing the other..

 

Thanks again for the great info, waynep71222.
The windshield wippers work.
Yes, I can find /reach the neutral switch plug/conection, it has 2 leads, one is a 2 wire and one 4 wire bullit.
I need to pick up an electrical tester to proceed.

The only wire that is hot is the white one on the 2 wire lead.  

Wayne , I don't mean to step on orangetang72's thread and I'll start a new one if need be, but I'm having the same issue. Would the things you mentioned apply to a '66 as well?  

this is identical info up through the mid 80s..   as long as the neutral safety and back up light switch is on the side of the transmission..

one thing...   some of you will find under the drivers side piston cover on the side of the transmission an aluminum . sometimes rubber coated folding tab.. thats designed to grip the wiring harness out of the neutral safety switch.. this prevents the wind from buffeting the harness and breaking the wires off right were they come out of the switch...

an additional an ODDBALL failure when the wires fatigue in the neutral safety harness..

when you turn the key to the ON position and the engine starts to crank...   this is because the wiring from the reverse light power circuit is shorted to the wire up to the wires up to the starter solenoid..  this is a weird problem that i have run into about a 10 times in 30 years..  almost always after a transmission rebuilder left the folding tab off.. so the wiring harness just flapped in the wind..   why does this happen.. the rebuilder does not usually remove and replace the transmission.. so he may not know what its for..  really pays to remove any non transmission related brackets before sending a transmission in..  

The tab is all good on the neutral switch. I think that I may have found the culprit there is a white wire with a purple stripe that comes from the back of the windshield wipper switch, that is sheared off  about 3" from the switch. I don't know were it goes !  

according to the 72 mustang wiring diagram that i have..

the white wire with a purple stripe goes to the upper right hand fuse somehow.. shared with the Turn signal  flasher..

do your turn signals work?  
do the wipers work? actually .. do the wipers PARK when you turn the wiper switch off?

all i have is a diagram..   not a whole car..

i do see a connection point where the white and purple wire is then connected to probably a short jumper and then to where the 3/1 connector is..    follow the 3/1 connector back through the firewall.. i am taking that the 3/1 connector is on the engine side of the firewall.. sort of next to the brake booster..

i have only been under the hood of 2 71/72 mustangs...  one belonged to the postman at the gas station i worked at.. it was a notchback with more than likely a 429..  and the other was a red version owned by a friend of my sisters.. who hung out at the playboy mansion..  i was just barely paying attention to the car..

i do own a 70 ranchero. 302. that is almost identical in part to mustangs..  

as for the cut or disconnected wire.. see if you can find the wire that leads under the dash board from the 3/1 connector..

is there a bullet connector on it??? when its just unplugged???  perhaps when the transmission was dropped.. the wires got pulled apart...

i know that on a friends 66 fairlane.. the wiring through the firewall had the insulation burned through and then melted in parts.. so the car would NOT start sometimes.. other times it would send up smoke signals..  

The turn signals work fine and the wipers "park" when I turn the wiper switch off. The wire seems just barely long enough to reach the fuse box. The end has a clean cut, not striped or with any soder or conection marks on the end.  

if the wipers park... and the turn signals work.. but the back up lights DON'T ..

that stub of white and purple stripe wire is supposed to connect to the neutral safety switch  3/1 connector..

find the 3/1 rubber connector on the firewall.. and then where the wires go into the dash..  

Success, after an hour of searching while standing on my head I found the other end of the white with purple striped wire, reconnected them and walla back-up lights are working !!!  

Congrats! Where did you find the other end?  

wonderful...   always glad to help...


braz...   find your rubber 4 wire connector that goes down to the side of the transmission..

follow that into the firewall..  the wiring usually goes through the firewall..  not always through the bulk head connector..

braz .. do you have a diagram for your 66.??  they are easy to find online..

i don't see a wire color for in one of the diagrams i have for the 66 mustang..

the power for the back up lights seem to come from the cigar lighter .. but that also supplies power to the Hazard flasher...

do you have power at your cigar lighter wire???    do the hazards work??  power on one side of the hazard flasher..  

that seems to go to the bottom fuse in the fuse block as shown in my diagram..

there seems to be an upper horizontal fuse...

then three vertical

and one at the bottom..     the left end is the circuit...  the right end is the power to the fuse and is also shared with the fuse directly above it..