1998 4runner trailer light wiring not working

How many and what colors are the wires on the trailer?

do you have a factory tow package on your vehicle?

does the trailer have brakes? If so what kind?

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

There are separate fuses in the fuse box for the trailer lights than for the vehicle lights. Ensure these fuses are good. The trailer lights work without any special settings on the vehicle light switch.
If you're getting no lights whatsoever (no brake, turn, or running) then you likely have a grounding issue. This is usually the white wire on the trailer lights.

Do you have a 7-wire, 6-wire, 5-wire, or 4-wire trailer light connector on the rear of your vehicle?

The 2006 Mazda Tribute w/o factory tow package can't accept a trailer wiring harness. If you install one you will probably burn out the central computer as I did. I had a top notch trailer hitch instaler try three different brand harnesses. I feel Mazda should reimburse me the cost of this car new, as I bought it to tow and was told that it could tow 3500 lbs. False representation!

Not sure which fuse you checked.
The Engine Compartment Fuse Panel ( Battery Junction Box / BJB ) is where the fuse is for the trailer tow adapter parking lamps.
Fuse # 5 is the fuse for the parking lamps, and the reversing lamps.

Next is the trailer tow adapter park lamp relay. This is what BJB Fuse #5 feeds, and the coil is operated by the truck's parking lamps. This is also in the BJB, Relay 201, it is the 1/2 size relay.

Not sure what you took a resistance reading from on the trailer tow adapter.

If you want, you can pull the trailer tow park lamp relay, and jumper the normally open contacts, which should provide power at the trailer tow adapters, regardless of the truck's lights.


This is the wiring diagram for the trailer tow park lamps

It is a possible option that the relays for the Stop / Turn are having an issue or the fuse in the Engine Mini panel is blown ( page 142 of the 1997 owners manual )

On the 1997/98 MY this is in the aux relay box in between the Engine Compartment fuse panel and the engine mini fuse panel.


The output of the MFS ( Multifunction switch ) triggers the relays, to use the trailer tow fuse to operate the trailer lamps. The fuse to supply power to the Normally Open contacts on the trailer relays should be hot at all times. You can verify this with the diagram below by metering from pin #3 to pin # 2 [ground for coil] or to another known ground.

These are 1/2 size Ford ISO relays, and can be jumpered to make testing easier ( and with this diagram you can bench test them with a meter to check resistance over the Normally Open contacts, when applying power and ground to the coil ).


I am not 100% sure on the 97/98 MY F-150 about the location of this connector, but the 99-03 have all the wires to the rear of the truck via a connector along the driver's side frame rail, that you can check for ( easiest with the spare lowered )


Start with the Fuse in the Engine Mini panel, to see if the 20A fuse is good and work back towards the trailer tow adapter via the relays. I am going with the obvious blown fuse for the Stop/Turn lamps for the trailer.

You'll have to follow the BROWN wire from the factory connector(with the running lights on of course) to the trailer connector and make sure you are getting power all the way to the two lamp fixtures. If so you've probably got two burned out 1157 bulbs or an inline fuse in the factory harness/ trailer harness.Good Luck, Dana

Then the problem is either with your trailer plug in, or the plug in on the truck. Use a test light to figure out which it is.

Is this a 4 way or 6 way connection system? If your truck is wrong, then all factory equipped trailer package harnesses would be wrong, tell your trailer guy...I don't think so.
Is this the first trailer you have hauled?
Let me know, and we will go from there.
REgards,

Look in the owners manual first. I have seen some of the fuse boxes under the back seat on the drivers side. Also try http://www.etrailer.com/faq-wiring.aspx. This should help. Mike

I take it the blinkers and brake lights work ok when not hooked up to the trailer? If yes, then the wiring to the tow hitch is not hooked up correctly. How many wires to trailer pig tail connection? U can have up to 7 depending on what you tow. Check to make sure these wires are hooked up from the truck to tow plug correctly: 7 wired---
brown-Rt turn and brake light, yellow-backup, white-ground, blue-electric brake, green-tail running lights, black-battery charger, red-left turn signal and brake light. Let me know if u have something other than 7 wire, I'll get the wiring color and source info for u.