No Trailer Lights

[RowdyRebel]

dropped my truck off at Mack for a new turbo & a few other misc. items on Friday....picked it up today and I'm not getting any trailer lights. Headlights come on, along with the center 3 cab marker lights. The second switch SHOULD have turned the outside 2 cab marker lights on, but it didn't. Not even the little green indicator light that lets you know the switch is in the "on" position was lit up.

I pulled the relays in the under hood fuse box and cleaned the connectors. There is continuity between the terminals you would expect to have continuity at based upon the schematic on the relay. Also checked the circuit breaker in that fuse box, along with the circuit breaker on the fuse panel inside the cab, and both had continuity. There was power to the relays and circuit breakers at both fuse panels. As far as I can tell, it SHOULD be working.

I drove home and hooked to the trailer, expecting to only have the center 3 DOT lights on the back since those usually come on with the headlights....but they didn't. The other switch that controls the outside 2 cab marker lights still wasn't working, so the trailer tail lights don't work.

Turn signals, brake lights, and 4-ways work.

Anyway, for the second light switch that controls the trailer tail lights, the plug is set up as follows:

1,2

X,3

X,4

X,5

X,6

#1 is a black wire, JX0044...and I'm guessing that is a ground.

#2 is a white wire, JX0019...and it only gets power when the headlights are on, variable voltage with the panel light switch, so I'm guessing that's the backlight for the switch.

#3 is a white wire, 35-D-08

#4 is a white wire, 35-C-08

#5 is a white wire, 35-E-08

#6 is a white wire, 35-B-08

NONE of these have power. I would expect at least 1 of them to be 12 volts, supplying the power for the lights. Anyone have a schematic so I can see where these wires go? I'm going to try to rig something up so I can run.....gotta leave in a couple hours. I figure for now, I'll run power from an auxiliary fuse block I had installed a while back up to a 35 amp switch, then stick leads into #3, #4, #5, and #6 one at a time and see what happens with each. When I find one (or more) that power up some lights that are out, I guess that's where I'll run a wire to......but I would like to eventually get it fixed correctly.

.............

OK, so I started experimenting with power...10A fuse so I wouldn't blow anything up.

#6 turned on the tail lights and the red side marker lights at the very rear of the trailer...the lights that switch is supposed to work.

#5 blew the fuse.

I replaced the fuse with a 15A since I am out of 10A fuses and gave up experimenting. I wired in 35A toggle switch to the auxiliary fuse block I added a while back, and ran the wire from the switch to #6.

Now, ALL of my tractor lights work. The trailer is another story. I still do not have the front amber marker lights...the amber turn signal light is supposed to be a running light, but it ain't...and I don't have the 3 center DOT lights on the back of the trailer. All of those are SUPPOSED to come on with the headlight switch, which is already a Wal-Mart special 35A toggle switch.

Yeah, I got tired of paying an arm and a leg to replace the OEM switch every couple months.

Anyway, I have tail lights now...so I think I ought to be OK and not draw TOO much attention today. Hopefully I can get it figured out the rest of the way this afternoon. I HATE electrical problems.

[rt76jim]

Use this web site hope it will ease your pain :-)

http://smrp-prod.macktrucks.com/spubs/default_ie2.htm#

[randyp]

dropped my truck off at Mack for a new turbo & a few other misc. items on Friday....picked it up today and I'm not getting any trailer lights. Headlights come on, along with the center 3 cab marker lights. The second switch SHOULD have turned the outside 2 cab marker lights on, but it didn't. Not even the little green indicator light that lets you know the switch is in the "on" position was lit up.

I pulled the relays in the under hood fuse box and cleaned the connectors. There is continuity between the terminals you would expect to have continuity at based upon the schematic on the relay. Also checked the circuit breaker in that fuse box, along with the circuit breaker on the fuse panel inside the cab, and both had continuity. There was power to the relays and circuit breakers at both fuse panels. As far as I can tell, it SHOULD be working.

I drove home and hooked to the trailer, expecting to only have the center 3 DOT lights on the back since those usually come on with the headlights....but they didn't. The other switch that controls the outside 2 cab marker lights still wasn't working, so the trailer tail lights don't work.

Turn signals, brake lights, and 4-ways work.

Anyway, for the second light switch that controls the trailer tail lights, the plug is set up as follows:

1,2

X,3

X,4

X,5

X,6

#1 is a black wire, JX0044...and I'm guessing that is a ground.

#2 is a white wire, JX0019...and it only gets power when the headlights are on, variable voltage with the panel light switch, so I'm guessing that's the backlight for the switch.

#3 is a white wire, 35-D-08

#4 is a white wire, 35-C-08

#5 is a white wire, 35-E-08

#6 is a white wire, 35-B-08

NONE of these have power. I would expect at least 1 of them to be 12 volts, supplying the power for the lights. Anyone have a schematic so I can see where these wires go? I'm going to try to rig something up so I can run.....gotta leave in a couple hours. I figure for now, I'll run power from an auxiliary fuse block I had installed a while back up to a 35 amp switch, then stick leads into #3, #4, #5, and #6 one at a time and see what happens with each. When I find one (or more) that power up some lights that are out, I guess that's where I'll run a wire to......but I would like to eventually get it fixed correctly.

.............

OK, so I started experimenting with power...10A fuse so I wouldn't blow anything up.

#6 turned on the tail lights and the red side marker lights at the very rear of the trailer...the lights that switch is supposed to work.

#5 blew the fuse.

I replaced the fuse with a 15A since I am out of 10A fuses and gave up experimenting. I wired in 35A toggle switch to the auxiliary fuse block I added a while back, and ran the wire from the switch to #6.

Now, ALL of my tractor lights work. The trailer is another story. I still do not have the front amber marker lights...the amber turn signal light is supposed to be a running light, but it ain't...and I don't have the 3 center DOT lights on the back of the trailer. All of those are SUPPOSED to come on with the headlight switch, which is already a Wal-Mart special 35A toggle switch.

Yeah, I got tired of paying an arm and a leg to replace the OEM switch every couple months.

Anyway, I have tail lights now...so I think I ought to be OK and not draw TOO much attention today. Hopefully I can get it figured out the rest of the way this afternoon. I HATE electrical problems.

Vehicle electrical problems draw me into a "fetal" position, sucking my thumb and moaning,,randyp

[RowdyRebel]

Vehicle electrical problems draw me into a "fetal" position, sucking my thumb and moaning,,randyp

Which is why I usually just take the easy way out.

This here's a fuse block I mounted to power auxiliary stuff. The junction block has the 6-conductor cable that controls different trailer functions (i.e. side dump controls), and all I have to do to add/change which wire does what is switch the wires around right there in the cab....nice & easy

Anyway, I ran a power wire from that fuse block up to this here switch....

...and then ran the second wire to the plug so the tail lights would come on. It was a LOT easier than fixing it the "proper" way.

....speaking of taking the easy way out of electrical problems, my '92 Ranger beater truck doesn't have tail lights...but it gets dark real early and I needed to drive it after dark to go pick up my Mack. I have tow lights mounted in the bumper, wired to a 4-round plug in the grille.....

....so I took my spare electric cord (I lost one, so made a second...then found the first...good thing, too) and cut off the 6-round that plugs into the towing vehicle to power the tow lights. Crimped an alligator clip onto the brown wire for the tail lights, and clipped it to the battery. Instant tail lights.

[rt76jim]

You may get all your trailer lights if you run a jumper from the brown wire to the black wire. The pins in a standard 6 pin plug are 1 oclock and 11 oclock are tail and clearance lights. Try checking that out.On the ranger it sounds like you might have a bad fuse in the dash light cicut, Just check it.

[RowdyRebel]

You may get all your trailer lights if you run a jumper from the brown wire to the black wire. The pins in a standard 6 pin plug are 1 oclock and 11 oclock are tail and clearance lights. Try checking that out.On the ranger it sounds like you might have a bad fuse in the dash light cicut, Just check it.

The 6-round has nothing to do with the trailer lights. Right now, the 6-conductor cable is coiled up behind my passenger seat because I'm not pulling a trailer that has anything I would control with it. The side dump trailers use 2 wires. Once I get around to changing the plug on the front of this trailer, I'll wire up another switch in the cab to power the work lights that are on the back. The other 3 wires go to nothing yet...the junction block just makes it quick & easy to add switches or change which switch does what.

I couldn't care less about the Ranger, really. It's just a beater truck/drag-behind...and the fuses were the 1st thing I checked. There's a bad wire somewhere...and I just haven't had the time or motivation to try and find it. To be honest, the tail lights are the LEAST of my concern with it. Other things I'm not too concerned about:

Cracked windshield

Exhaust rotted off/nonexistent

Choke/cold idle issues

Hydraulic clutch loses fluid & gotta top it off occasionally or I lose the clutch

Brake line to the front right broke, so I pinched it off.

Doors & hood latch are off my '86 Ranger

Passenger side mirror bungee corded on

Grille is one I made out of scrap metal

Tailgate quit opening, so I just have a net there now

Bed is beat up

Fenders are dented (brother wrecked it before I bought it off him)

etc...

etc...

etc...

I've had the thing over 4 years now, and haven't spent more than $50 on it beyond gasoline and 1 oil/filter change per year. Apart from the rough idle when it's cold, it runs like a champ and is fun as hell to drive...compared to the Mack, it's like a go-kart.

Now for more on the crazy Mack issues....

I rigged up that switch so my tail lights would work on the trailer, and they do. Didn't have any other lights, though, which are all (on this trailer) usually controlled with the headlight switch, not the switch that wasn't working and is now rigged. 45 miles into my day on Tuesday, those other lights magically began working, and they worked for the remainder of the day.

Today, same issue....my rigged switch turned on the trailer tail lights. All tractor lights worked. No trailer lights except those operated by my rigged switch. I climbed into the cab to leave, and when I looked in the mirror, the lights which HAD been out were now on...and they worked fine for the duration of the day.

So, I'm not sure if there's a relay sticking somewhere, or a loose connection, or a corroded wire, or what the deal is. Next time it goes to the shop, I'll let them try to find the problem...I HATE electrical problems, especially when I have no clue where the wires go once they disappear into the dash.

[fxfymn]

Sounds like a bad ground somewhere in the trailer to truck connection.

Spent a lot of time working with an old timer who always told me "When you can't find out what's wrong it's always something simple. Everyone looks for the worst thing, not the simplest."

[poonamt93]

Because you have increased the number of lights, you have also increase3d the amperage in the circuit, so of course you will have a faster flasher cycle. you should be able to find a different flasher unit for a trailer option. that should take care of the problem. the next problem you might run into is the brake light switch, increased amperage will cause that one to get hot and melt, same idea, replace it with a higher load capacity switch, after that you still might have a problem with blown fuses in the brake lamp and or turn signal circuits.