Tail light, Parking light, Running Light, Dash Light Problems
Mountain Pass
Joined: Feb 2013
Posts: 132
Likes: 0
From: Southern Arizona
Replacing the tail/running light relay fixed my problem with tail lights on no running lights, tail lights off running lights on.
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
The only relay he has is one for the trailer running lights. He has no relay that I saw in the diagrams for the truck's running lights.
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
The only relay they use is one for the trailer tow circuit. The only other oddball thing in the circuit is the vehicle security module, that's what blinks certain running lights when the key fob is pushed to unlock the doors.
Hotshot
Joined: Jan 2004
Posts: 19,762
Likes: 1,079
From: St Louis
An 89 is two generations older than the truck under discussion....
New User
Joined: Mar 2015
Posts: 7
Likes: 0
97 e350 6.8l bus
Had this about a week or so all the lights worked before except for 2 of the cab over lights replaced all cab over lights with new base lens and bulbs and all of the other lenses and lights got everything together hand now there is a problem with the cab over lights and running lights not working unless the switch is messed with idk what happened but any help would be great
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
You are pulling the headlight switch out halfway and they are working? That's a sign you have lost your running lights feed to the headlight switch.
The headlight switch has a couple of different separate power sources. You have lost your running light power source, and putting the switch in the half-way position crosses up the contacts inside and the running lights are using the headlights power source.
If I am still on the right track, first thing to do is check the running lights fuse. If it's good, pull the headlight switch and check for power on the tan/white wire. They had a big problem with it burning off in older trucks and vans. I would have though they would have fixed it by 97 but maybe not.
The headlight switch has a couple of different separate power sources. You have lost your running light power source, and putting the switch in the half-way position crosses up the contacts inside and the running lights are using the headlights power source.
If I am still on the right track, first thing to do is check the running lights fuse. If it's good, pull the headlight switch and check for power on the tan/white wire. They had a big problem with it burning off in older trucks and vans. I would have though they would have fixed it by 97 but maybe not.
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New User
Joined: Mar 2015
Posts: 7
Likes: 0
So it was fuse 10 that blew replaced it rechecked all the cab over lights that were giving me an issue found the center light bulb contact was probably the cause of it all sense that was bent and probably grounded itself out
Freshman User
Joined: Mar 2009
Posts: 43
Likes: 0
From: Burbank, CA.
Lights go out for 3 to 5 seconds
Power going in on the tan/white, and nothing coming out on the brown with the switch in either on position means the switch is bad. Check the brown wire for voltage, that's the one going out to the lights. You could take your hot test wire and stick it on the brown and all the running lights should light up.
Only when I have connected my 7pin to my camper or a variety of trailers , my dash and exterior running lights on the truck , trailer and or camper will go out for about 3 to 5 seconds and then come back on . This repeats every 5 minutes or so . I have noticed that my dash lights will go a little dim before they go out and then come back on nice and bright . Btw it's a 1978 f250 .
Lance
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
I am stumped ... I've been following this thread hoping to find someone with my electrical issue , it's a weird one :
Only when I have connected my 7pin to my camper or a variety of trailers , my dash and exterior running lights on the truck , trailer and or camper will go out for about 3 to 5 seconds and then come back on . This repeats every 5 minutes or so . I have noticed that my dash lights will go a little dim before they go out and then come back on nice and bright . Btw it's a 1978 f250 .
Lance
Only when I have connected my 7pin to my camper or a variety of trailers , my dash and exterior running lights on the truck , trailer and or camper will go out for about 3 to 5 seconds and then come back on . This repeats every 5 minutes or so . I have noticed that my dash lights will go a little dim before they go out and then come back on nice and bright . Btw it's a 1978 f250 .
Lance
What I would do is add a relay under the hood that is controlled by the running lights. Run a new circuit with a fuse directly off the battery, run through the relay, and then run a wire down and all the way back on the frame to the trailer plug. This new circuit will drive your trailer lights. It sounds like you have too much load on the trucks original circuit, and it's overloading the headlight switch circuit breaker.
Another option would be to change all the running lights over to LED. I would leave the taillights alone though on the truck.
Here's what I go from the other site;
1) The headlamp switches on all 1970 Ford trucks (except "W" models) employ two integral circuit breakers, one 12-amp for the headlight circuit and one 15-amp for auxiliary circuits. Connections to any point in the circuits controlled by the headlamp switch will be on the auxiliary circuit breaker, except connections to the #12 circuit (headlamp hi-beam, green wire/black stripe), the #13 circuit (headlamp low-beam, red wire/black stripe) and the #15 circuit (feed wire to the the dimmer switch, red wire/yellow stripe. Connections to the 12-13 or 15 circuits (headlamp bulb circuits) should be avoided.
If the total load on either headlamp circuit breaker exceeds the breaker rating, the headlamps or taillamps will cycle on and off indicating the overload. If this occurs, a portion of the added lights must be wired through a relay, feeding the relay coil from the headlamp switch.
The feed from added lights to be controlled by the headlamp switch should be terminated in a male bullet connector and be connected to the female bullet take-out (brown wire -- 285 circuit) on the left-hand side of the instrument panel harness (near the emergency brake). If the vehicle has roof marker lights, this bullet will be occupied by the feed from the roof wires. In this case fabricate a "Y" jumper to permit both connections to the single connector.
Rear lights to be controlled by the headlight switch can be spliced into the #285 circuit (brown wire) at any point in the taillamp harness.
NOTE: The special Camper option on light trucks provides a plug connector on the left-hand frame rail to which taillamp connections can be made directly.
Freshman User
Joined: Mar 2009
Posts: 43
Likes: 0
From: Burbank, CA.
I got the below from the fordification site. Even though it's for a older truck than yours, it sounds like your headlight switch still has dual circuit breakers in it.
What I would do is add a relay under the hood that is controlled by the running lights. Run a new circuit with a fuse directly off the battery, run through the relay, and then run a wire down and all the way back on the frame to the trailer plug. This new circuit will drive your trailer lights. It sounds like you have too much load on the trucks original circuit, and it's overloading the headlight switch circuit breaker.
Another option would be to change all the running lights over to LED. I would leave the taillights alone though on the truck.
Here's what I go from the other site;
1) The headlamp switches on all 1970 Ford trucks (except "W" models) employ two integral circuit breakers, one 12-amp for the headlight circuit and one 15-amp for auxiliary circuits. Connections to any point in the circuits controlled by the headlamp switch will be on the auxiliary circuit breaker, except connections to the #12 circuit (headlamp hi-beam, green wire/black stripe), the #13 circuit (headlamp low-beam, red wire/black stripe) and the #15 circuit (feed wire to the the dimmer switch, red wire/yellow stripe. Connections to the 12-13 or 15 circuits (headlamp bulb circuits) should be avoided.
If the total load on either headlamp circuit breaker exceeds the breaker rating, the headlamps or taillamps will cycle on and off indicating the overload. If this occurs, a portion of the added lights must be wired through a relay, feeding the relay coil from the headlamp switch.
The feed from added lights to be controlled by the headlamp switch should be terminated in a male bullet connector and be connected to the female bullet take-out (brown wire -- 285 circuit) on the left-hand side of the instrument panel harness (near the emergency brake). If the vehicle has roof marker lights, this bullet will be occupied by the feed from the roof wires. In this case fabricate a "Y" jumper to permit both connections to the single connector.
Rear lights to be controlled by the headlight switch can be spliced into the #285 circuit (brown wire) at any point in the taillamp harness.
NOTE: The special Camper option on light trucks provides a plug connector on the left-hand frame rail to which taillamp connections can be made directly.
What I would do is add a relay under the hood that is controlled by the running lights. Run a new circuit with a fuse directly off the battery, run through the relay, and then run a wire down and all the way back on the frame to the trailer plug. This new circuit will drive your trailer lights. It sounds like you have too much load on the trucks original circuit, and it's overloading the headlight switch circuit breaker.
Another option would be to change all the running lights over to LED. I would leave the taillights alone though on the truck.
Here's what I go from the other site;
1) The headlamp switches on all 1970 Ford trucks (except "W" models) employ two integral circuit breakers, one 12-amp for the headlight circuit and one 15-amp for auxiliary circuits. Connections to any point in the circuits controlled by the headlamp switch will be on the auxiliary circuit breaker, except connections to the #12 circuit (headlamp hi-beam, green wire/black stripe), the #13 circuit (headlamp low-beam, red wire/black stripe) and the #15 circuit (feed wire to the the dimmer switch, red wire/yellow stripe. Connections to the 12-13 or 15 circuits (headlamp bulb circuits) should be avoided.
If the total load on either headlamp circuit breaker exceeds the breaker rating, the headlamps or taillamps will cycle on and off indicating the overload. If this occurs, a portion of the added lights must be wired through a relay, feeding the relay coil from the headlamp switch.
The feed from added lights to be controlled by the headlamp switch should be terminated in a male bullet connector and be connected to the female bullet take-out (brown wire -- 285 circuit) on the left-hand side of the instrument panel harness (near the emergency brake). If the vehicle has roof marker lights, this bullet will be occupied by the feed from the roof wires. In this case fabricate a "Y" jumper to permit both connections to the single connector.
Rear lights to be controlled by the headlight switch can be spliced into the #285 circuit (brown wire) at any point in the taillamp harness.
NOTE: The special Camper option on light trucks provides a plug connector on the left-hand frame rail to which taillamp connections can be made directly.
Lance