Electrical 1986 (5-spd) mustang reverse lights not working.

Driver460sz

Member
Jan 14, 2019
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Bulbs are good, all others work, fuse is good. Checked the wiring/plugs on the trans and they are connected and seem fine. The car does have wires tapped and "updated" under the dash and around the fuse panel. God knows what that is at this juncture and if it has anything to do with the reverse lights (Waiting to hear from the previous owner). At the back of the car, there is a little device (a box thing) that has a ground (Black) and a red leading out (What is this device?). The red wire was cut, which I re-attached to see if that did anything. Made no difference.

Anywho.....Outside of trying a new trans harness sensor.....whats the next step in the diagnostic process? Any hidden switches maybe???

Thanks y'all
 
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JosTee

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Apr 27, 2019
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Normally there is a switch on the transmission. So when you select reverse this switch is activated. Can you find the wiring and maybe check if there is voltage on one of the wires. Can you short the pins when there is voltage on it, rearlight should go on then.Otherwise remove the switch from the housing and see /measure if it is working if you have a multimeter.
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
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Only thing you need to do in an auto to 5-sos swap is unhook the harness from the AOD, hook up the small 1 foot long t5 harness and plug it into the reverse light plug on the side of the t5.

If you unplug it from the t5 and jump the 2-wire plug out, the lights come on
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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not getting picky here but terminology here can be important, in this case it would be a 'reverse light switch'.
sensors
senders
switches
then maybe I'm just getting old and not kept up with the changes

:D
 

Driver460sz

Member
Jan 14, 2019
48
24
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41
New Hampshire
Well............this is getting fun! What I know is that the speedo doesn't work, the car starts without depressing the clutch, and the reverse lights do not work. I do know that the circuit closes when put in reverse as checked by jumping a wire from the battery to the posts on the trans and using a meter. It doesn't seem anything is coming through from the harness in the car to the trans tunnel.

Maybe need a speedo gear for speedometer, check to see if a neutral safety switch got bypassed. From what I understand the NSS and the reverse lights interlink and this could be the problem. Somewhere near the master cylinder is the location, I believe.
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
33,124
9,262
224
Massachusetts
Reach up under the dash by the clutch switch, find the two small loose plugs. One gray, one clear. Remove the jumper in one and install both into the clutch switch.

As far as as the reverse lights, all you do in a swap is unplug the harness from the AOD and plug this into the harness and connect to reverse light switch


Red loop jumps the nSS

If you don't have power on the wires, pull the drivers kick panel, locate the 8-wire trans harness plug (aod will have 6-wires due to no wires for the ngs on top of the trans) and test for power on the reverse wiring.

I'll see if I can get wiring colors for you. What year is the car
 

Driver460sz

Member
Jan 14, 2019
48
24
18
41
New Hampshire
Reach up under the dash by the clutch switch, find the two small loose plugs. One gray, one clear. Remove the jumper in one and install both into the clutch switch.

As far as as the reverse lights, all you do in a swap is unplug the harness from the AOD and plug this into the harness and connect to reverse light switch


Red loop jumps the nSS

If you don't have power on the wires, pull the drivers kick panel, locate the 8-wire trans harness plug (aod will have 6-wires due to no wires for the ngs on top of the trans) and test for power on the reverse wiring.

I'll see if I can get wiring colors for you. What year is the ca
Reach up under the dash by the clutch switch, find the two small loose plugs. One gray, one clear. Remove the jumper in one and install both into the clutch switch.

As far as as the reverse lights, all you do in a swap is unplug the harness from the AOD and plug this into the harness and connect to reverse light switch


Red loop jumps the nSS

If you don't have power on the wires, pull the drivers kick panel, locate the 8-wire trans harness plug (aod will have 6-wires due to no wires for the ngs on top of the trans) and test for power on the reverse wiring.

I'll see if I can get wiring colors for you. What year is the car
Awesome and thanks. It is a 1986.
 

Driver460sz

Member
Jan 14, 2019
48
24
18
41
New Hampshire
Reach up under the dash by the clutch switch, find the two small loose plugs. One gray, one clear. Remove the jumper in one and install both into the clutch switch.

As far as as the reverse lights, all you do in a swap is unplug the harness from the AOD and plug this into the harness and connect to reverse light switch


Red loop jumps the nSS

If you don't have power on the wires, pull the drivers kick panel, locate the 8-wire trans harness plug (aod will have 6-wires due to no wires for the ngs on top of the trans) and test for power on the reverse wiring.

I'll see if I can get wiring colors for you. What year is the car
86
 
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