Tail lights not working neither are the dash lights or number plate lights,have fitted a new light switch still the same

Check the fuse. A bad bulb can cause a fuse to blow.

The tail lights and dash lights are on two different circuits only related by the headlight switch. I would look for a problem there.

The tail and marker lights and Instrument lights are on the same circuit so both will go out if the fuse for this circuit blows. If fuse continues to fail, check the tail light or marker globes, including the globes for the number plate, for a globe that may have an internal short causing the fault and replace as necessary. As you have already checked the wiring near the light fittings for any chafed wires that could be shorting to the body causing the fault, then a closer inspection of the wires inside all the light assemblies for any shorts may be needed.

It could also be that the instrument dimmer control has failed and is causing the fault. The electronic bits inside the dimmer control for these lights sometimes go faulty. Try disconnecting the connecting plug on the rear of the dimmer control and checking if fuse still blows. If fuse continues to fail, then the fault in the tail and marker lights circuit.

Remove all the tail, number plate and running light globes from the light assemblies and leave the instrument dimmer control disconnected and check if fuse still blows.

Disconnect the plug near each of the light assemblies to see if any of the individual assemblies is causing the fault. With all light assemblies disconnected and fuse continues to fail, then the fault must be in the main wiring loom some where.

If you have a Multimeter, it could be used to determine which light assembly has a fault between the lamp supply and earth connection.

Hi
There are a couple of wiring diagram and manual available on the net. The relay you are talking about is the park lamp relay which supplies power to the tail lamps, license plate lights and both front and rear park lamps. If the park and plate lights are working the light switch, relay and supply power are good. You need to verify for a broken brown wire to the tail lamps (assuming the sockets, lamps and grounds on both tail lights are good) .If none of the lamps are working then the 15A fuse number 3, the light switch or the park lamp relay could be bad (note different contact in the main light switch work the other lights)

You can find a wiring diagram and component location at
www.autozone.com and http://www.pdfgeni.com/book/1998-ford-ranger-wiring-diagram-pdf.html

Let us know if you want something more else accept the solution.
Thanks for contacting fixya.com

probable short in headlight switch

then the problem lies near the dash because dash,tail,and license plate lights work on same circuit

I would suspect the switch itself,or the wire from it ,as if it were a ground issue i do not expect it to effect the dash.You can usually check by the relay socket(on whatever lighting relay) on pin 1,whether you have 12v or not when you turn on the switch and a constant 12v on another,or fit a jumper lead from the constant 12v to the opposite side(4 pin relay)to test the circuit and operate the lights.

Hope this helps.

Check the switch that brightens and dims the dash lights

head light switch is bad

hi as you have checked all fuses for these light ok? and other lights are all working may i suggest you check the relay for side/tail lights which also includes licence plate light first it sound like the relay has failed if you look under fuse/relay cover you may find map indicating location? i would try this first b4 switch hope this helps?