My dad's Forzda lost tail lights, no blown fuse in the cab. Found the under hood fuse box. None of the regular fuses were blown...

No obvious new damage to the wiring harness on the frame. Front parking lights work fine.

First i would like to remedy the light issue and secondly i would like a chart or something that spells out the fuse block applications under the hood.

Brent

 

Tell me you at least checked the bulbs

 

We not only checked the bulbs but we ran a hot jumper to the trailer plug and lit up the tail lights and clearance lights on the topper...
Brent

 

No one?
I am guessing that some where in the wiring, the lights are separated front to rear.

Brent

 

a few thoughts......what you are looking for is called a wiring diagram not a chart.......get a haynes manual they have the diagrams. the fuse block application is called the "distribution box"......your owners manual shows the layout......you can get an OM here https://www.fleet.ford.com/maintenan...ls/default.asp You said you checked the connection at the bumper. You alos check the trailer connection for a short?

 

By "chart" I meant the description as found on pg. 314 of the OM... Thanks for that link.

I have a manual with the schematics. I do not see anything there that explains my loss of lighting to the tail lights but not involving the front marker lights as I expected to find.

I will disconnect the trailer light adapter that we put inline a few years ago... nothing appears damaged in any of the factory or added wiring.

Brent

 

Lets think about this some more.
If you don't have any blown fuses & you ran a parallel B+ lead to the rear lamps & that didn't bring joy, it would suggest to me that you have an open ground to the rear lamps. So provide a good ground to the rear lamps with a jumper lead & see if they'll light up. If so, follow the rear lamp ground wire & check it's ground connection point. It should be clean, bright & tight.

If the added trailer connector isn't an OEM part, good idea to disconnect it on your trouble shoot.

Let us know what you find.

 

Actually, the hot jumper to the trailer tail light was good results... lit 'em all up fine.
Brent

 

BTW, the stop lights are working.
Could a bad ground cause me to lose the tail lights but the stops still work fine?
TIA,
Brent

 

Stop & Tail lights use the same ground point, so thats not likely your problem.

Using a multimeter, or test lamp, go back to the spot where you jumped the B+ 12 volts to & the parking lights lit, then work your way forward to & through each electrical splice, to see where your loosing B+ to the tail lights.

The wire color for the tail lights going forward is Brown. & it goes through 3 splices before getting back to the light switch, or to the park lamp power relay, in the under hood power distribution box, if you have the remote control alarm/anit-thieft option.

In more detail, if the license plate lights work, you have B+ that far at splice S1004, so proceed back toward the tail lights to find splice S401, which will have two Brown wires branching off to feed both the left & right side park lamps.

If the license plate lamps Arent lit, then the B+ feed problem is somewhere between their splice (S1004) and splice S234 off which the front & rear park lamps feed, IF you don't have anti-thief, or off the under hood park lamp power relay, IF you have anti-thief. WHEW!!!! lol

So check to see if the license plate lamps work. If so, your in luck, as the tail light B+ feed problem is likely close by at splice S104.

If the license plate lamps aren't lit, then you'll need to trace the Brown wire forward & look for a cut wire, or maybe bad connection at splice S234 where the rear & front park lamps branch off , if you don't have anti-thief, or a bad connection at the parking lamp power relay, if you have anti thief.

Seeing as how the front parking lamps work, their connection at splice S234, the light switch & parking lamp power relay if you have one, is likely ok.

A picture is worth a thoudand words, but I can't post one, so just take the voltage trouble shoot one step at a time & you'll find the problem.

 

Is your Mazda equipped with the lamps out warning system?

Is it indicating a problem on the dash?

If not the lamps out module is a prime suspect. Some of the guys here on FTE have found loose solder connections at the LOM & fixed with a soldering gun.

As pawpaw mentioned a picture is worth a 1,000 words.

The wiring diagrams in a Haynes or Chiltons are slightly better than useless.

What Haynes or Chiltons tries to do in 5 or 6 pages of diagrams the factory wiring diagrams do in about 200 pages.

Example the factory wiring diagrams for m 97 Explorer show the exterior lamps wiring diagram on 2 pages & in a couple of seconds I know exactly how the parking lamps are wired & where the LOM module/every splice/fuse/connector/relay are located.

You cant fix something until you understand how it works.

The manual for a 96 Ranger (same as your Mazda)is 21 bucks at helminc.com.