Front Signals Don't Work with Parking/Headlights On

[jamcomanche]

My 87 had an issue with the front parking lights and corner markers when i bought it. They didn't work at all. The dummy before me spliced in a third parking light on the driver's side trying to get them to work. 

 

I cut all the lights off and reconnected 2 properly using disconnects on all 3 wires for each light. I followed the Haynes schematic to connect them.

 

The corner markers now work, and the turn signals work when the lights are in the off position. (though they are a little dim)

 

When i turn on the parking or headlights, the signals don't blink at all. They just stay illuminated. Tail lights/ signals work fine 

 

Does anybody have any idea what the problem might be? I'm considering tapping a new ground for the lights to see if that might be the issue.  Any help is appreciated.

 

 

[eaglescout526]

Have you checked the front sockets for rust and corrosion? They are a common problem and is highly recommended to replace them with newer XJ front sockets to remedy this problem. 

[jamcomanche]

1 hour ago, eaglescout526 said:

Have you checked the front sockets for rust and corrosion? They are a common problem and is highly recommended to replace them with newer XJ front sockets to remedy this problem. 

Yeah, the sockets are in good shape. I even cleaned them up a bit myself.  If I can't find any other possible solution and tapping a new ground for them doesnt work, then ill probably order some new ones.

[eaglescout526]

Okie dokie, we await your report back. 

[jamcomanche]

26 minutes ago, Manche757 said:

It appears that your headlight circuit if feeding the signal lights.  Recheck your connections

I was thinking that this could be a possible cause, but that makes me think that the wiring harness would have to have been altered further up the chain.

This is the diagram I used to wire up the light sockets. I connected the wires for the park/turn lamps by color.

 

 

Anyway, I'll have to do some more troubleshooting and check further up the harness I guess.

[jamcomanche]

Can anybody confirm the socket type that is supposed to go in the front signal lamps?  The ones I have are S-77 three-wire sockets, which I don't show as being standard for AMC/Dodge/Jeep.  I can only find the S502's as being standard for the rear lamps.

[eaglescout526]

I have a part number if it’ll help. 03764863

[gogmorgo]

Are you sure you hooked up the lights correctly? The dual filament bulbs use the dim filament for the parking lights and the bright one for the turn signal.

If you hook them up opposite, the turn signals will be dim, but the markers will come on nice and bright, but might be so bright you don’t notice the signal filaments coming on.

It’s also possible to hook up the ground to one of the filaments, which will cause it’s own set of issues.

I wouldn’t rely on wire colours to establish what’s what, especially not from a Haynes manual that covers a broad spectrum of model years. I would use a test light on the truck harness, see what comes on solid with the headlights, what blinks with the turn signals, and the other will be your ground.

You can also test what each wire on the socket is for by putting power and ground to the wires. Start by grounding any of the three wires and put power to one of the other two. If nothing lights up you have a problem with something. If both filaments light dimly, the wire you have nothing hooked to is your ground. Otherwise, trial and error to pick which one is the ground, and which ones light up the bright and less bright filaments. In most cases you don’t want to just push power willy-nilly into things to see what they do, but in the case of these dual-filament bulbs you won’t create a dead short and it’s no big deal to accidentally run the filaments in series, which is the worst case outcome so long as you only have two wires hooked up at a time.

 

As far as cleaning up the sockets goes, I’ve never had much success. If it’s just full of old dried up grease, hit it with brake cleaner, but if you’re scrubbing corrosion off it’s almost impossible to get enough pressure on it without spreading the contacts. 

[Eagle]

1 hour ago, jamcomanche said:

Can anybody confirm the socket type that is supposed to go in the front signal lamps?  The ones I have are S-77 three-wire sockets, which I don't show as being standard for AMC/Dodge/Jeep.  I can only find the S502's as being standard for the rear lamps.

 

There is (or used to be) a socket in the HELP! line that all the parts chains carry that's a perfect replacement. It's not listed for Jeeps, it's listed for some Ford vehicle.

 

The problem is that you've lost the ground to the parking/turn lamps. They're trying to find a ground through the headlight circuit but, when you turn on the headlights, that can't work. You need new sockets.

[jamcomanche]

5 hours ago, gogmorgo said:

I wouldn’t rely on wire colours to establish what’s what, especially not from a Haynes manual that covers a broad spectrum of model years. I would use a test light on the truck harness, see what comes on solid with the headlights, what blinks with the turn signals, and the other will be your ground.

 

Ok, fair enough.  I also have no idea if the sockets that came with the truck even belong to it, so I'll try flipping them around and see what happens.
 

5 hours ago, gogmorgo said:

As far as cleaning up the sockets goes, I’ve never had much success. If it’s just full of old dried up grease, hit it with brake cleaner, but if you’re scrubbing corrosion off it’s almost impossible to get enough pressure on it without spreading the contacts. 

I used WD-40 Electrical Contact Cleaner spray which does a good job at cleaning up corrosion with the help of a brush. 

 

4 hours ago, Eagle said:

 

There is (or used to be) a socket in the HELP! line that all the parts chains carry that's a perfect replacement. It's not listed for Jeeps, it's listed for some Ford vehicle.

 

The problem is that you've lost the ground to the parking/turn lamps. They're trying to find a ground through the headlight circuit but, when you turn on the headlights, that can't work. You need new sockets.

 

The S-77 fits the housing perfectly. I was mainly curious about it because of the wire colors.

 

Thanks to you all for the advice.  I'm going to start with flipping the connections. If that doesnt work I'll probably tap a new ground near the lights. If neither of those work I'll buy new sockets.

[jamcomanche]

21 hours ago, eaglescout526 said:

Okie dokie, we await your report back. 

 

18 hours ago, gogmorgo said:

I wouldn’t rely on wire colours to establish what’s what, especially not from a Haynes manual that covers a broad spectrum of model years. I would use a test light on the truck harness, see what comes on solid with the headlights, what blinks with the turn signals, and the other will be your ground.

 

I went out this morning and swapped connections on the non-ground wires (blue+brown/blue+gray) so that the blue was connected to the brown/gray on either side and that has fixed my problem.  It's funny to me that both sockets had the same wire colors as the wiring harness, yet they were colored backwards.  Definitely can't be the stock sockets.

 

Signals are working perfectly now with lights on or off.  Thanks for your help

[elliot]

On 9/29/2021 at 7:22 AM, jamcomanche said:

 

 

I went out this morning and swapped connections on the non-ground wires (blue+brown/blue+gray) so that the blue was connected to the brown/gray on either side and that has fixed my problem.  It's funny to me that both sockets had the same wire colors as the wiring harness, yet they were colored backwards.  Definitely can't be the stock sockets.

 

Signals are working perfectly now with lights on or off.  Thanks for your help

Would you mind walking me through what you did to swap the connections? I don’t have any electrical experience and I’m having the same problem with my turn signals that you were having 

[gogmorgo]

13 hours ago, elliot said:

Would you mind walking me through what you did to swap the connections? I don’t have any electrical experience and I’m having the same problem with my turn signals that you were having 

Unless you know someone was in there swapping your wires around, this is unlikely to be your issue. What exact problem are you having?

 

[jamcomanche]

On 10/1/2021 at 11:07 AM, elliot said:

Would you mind walking me through what you did to swap the connections? I don’t have any electrical experience and I’m having the same problem with my turn signals that you were having 

 

There are 3 wires that come out of the socket. The 2 that come out of the end of the socket are your switch and signal wires, these are usually blue and gray, or blue and brown depending on the side of the truck.  The 3rd wire goes to the outside of the socket in a separate outlet.

 

I swapped the two wires that I had connected the blue and gray / blue and brown wires to. So for me, instead of blue connecting to blue on the harness, I had to connect blue to gray, and blue to brown on the other side.

 

I tried uploading an image to help but it failed for some reason.