No Headlights!

[MrFurious]

So I ran uptown last night for some smokes and a 6-pack, and on the way home my headlights quit working. I've been having headlight issues for several months now, but it usually consisted of only one or the other going out from time to time. When it first started happening I could usually get it back on by smacking it with my hand a time or two, but in the last month or so that hasn't worked.

Headlights are both good (tried them on another vehicle), so that left the harness and the switch as the possible problem areas. Cleaned all the grounds and plug sockets, applied fresh dielectric grease to all the sockets, still nada.

Since I wanted to upgrade to H4 headlights anyway I ordered Jared's harness (very nice BTW!). Unfortunately this didn't help any as it uses the current through the factory headlamp harness to activate the relays on the new harness. In other words, I got it installed this morning and still no headlights.

Pulled out the multimeter and started checking things. Started at the sockets on the new harness...no voltage. Then checked the sockets on the factory harness....no voltage there either. The only other things I know of inline between the harness and the power source are the switches.

So now for the questions. Is there a way to test the headlight switch to verify it's the culprit? Also, if the dash switch is bad will that prevent the high beams from working as well (I'm assuming it would).

And of course....the switch is a special order item at AutoZone. (insert several 4-letter words here)

[Crazy_Jeepman]

Pull the plug off the lightswitch and check for power there. If you have power at the light switch then there would be your problem. If not you would have to trace it back to the fuse box. Headlight switch has a breaker in it, it will trip and reset when it cools down. However over time they will get weak and trip for no reason, and possibly not reset.

[gsmikie]

check the headlite dimmer switch

[chaos]

I had a problem once with the lights, and it turned out to be that someone had put a single pin bulb in the rear taillight where a dual pin should have been, it shorted out the lighting system. I can't exactly remmeber if it was the head light that failed thoug.

[HOOT]

If you buy a new switch ( which I recommend, if it's old) , make sure you get the right one. Take your old one in with you. Compare the plug connections.
KOI ,Federated Auto parts shows 2 different switches. One works the other almost works.

Replacing the dimmer switch and dash switch made a HUGE difference in my lighting. NO more headlight failures.


A bad dimmer switch will kill the lights. Wires down near it also get kicked and scuffed from ones' feet.
Good Luck

[MrFurious]

Did a little more probing on the Jeep after finishing up the brakes on the truck. High beams work, so I'm thinking the floor switch is good (IIRC Dan said he had replaced it after he bought it).

Ordered a new dash switch from AutoZone this afternoon so hopefully it will the right one. I'll be sure to pull the old one and take it in for comparison before I accept it. I'll probably go ahead and pick up a floor switch as well just to be on the safe side (I know my luck...I'll need it if I don't get one).

[JeepBountyHunter]

I know by now it's redundant to say it..but almost all my CJ's had the issue you mention...and it was always that infernal floor dimmer switch..and I can remember my 78 CJ-7 having high beams and nothing else...till I changed that switch out...
Good luck..your going the right route anyways replacing those..

[MrFurious]

I'll take a look at the wiring on the floor switch and clean things up a little and add some dielectric greese to the connections. Maybe I'll get lucky and they'll start working so I don't have to drive the truck down your way today Aaron...sad to say, but the ol'FSJ gets much better gas mileage than my 93 F150. Guess 35's and 4.30 gears tend to have that effect. lol

And no, I'm not spraying the Jeep this weekend as I had planned to. I was all ready to order the paint when the house plumbing took a crap (pun intended). Major bummer! Guess the Jeep will continue to wear urban camo on the passenger side through the summer now.

I am going to see if I can find somewhere that can still order custom rattle cans so I can shoot the primered spots as a temp fix. At least then it would all be one color and I wouldn't have to worry about the primer drawing moisture as much.

[MrFurious]

Ok, stupid questions of the day....since the TSM doesn't bother telling you what the different wires are for.

1) On the floor switch I have red wire w/TR, two gray wires w/TR, and a solid gray wire. Which ones do I need to probe to see if power for the low-beams is getting out for the headlights? Should be either hte gray or gray w/TR, but which is low-beam and which is high?

2) The dash switch has a Red, a White, a Red w/TR, a Black, and an Orange wire. Black and orange go to the dome lamp, so that leaves the reds and the white. The solid red looks to be the source power, and the white looks to go to the door buzzer/ignition switch. It that's right, then the Red w/TR should be the power feed to the dimmer switch, correct?

Also, I had an odd development yesterday that might be related. When I replaced the dimmer switch with a new one, all the sudden a buzzer started working (never heard it before), but only when the engine is running. The only buzzer I can find in the TSM wiring diagram is the Headlight Warning Buzzer, so I'm guessing it's only supposed to go off when you turn off the ignition and leave the headlights on.

Now since the white wire from the dash headlight switch runs to the buzzer, could that be a sign the switch has shorted out inside? I basically had to pull the buzzer to shut it up, so it's an incomplete circuit right now.

Hopefully my new dash switch will come in today, but I'd like to know if that's going to be the fix or if I should go ahead and start looking for something else.

Update: New switch came in, still no low-beams.

I'm really starting to think that constant buzzer is the key here. It's essentially working backwards as I can leave the headlights on with the engine off and no buzzing, but if I have the headlights off and the engine running it buzzes constantly. The real question is 1) why's it keeping my low-beams from working, and 2) with both switches now replaced what could be the major malfunction?

Now for the really strange part. Checked the TSM wiring diagram and supposedly the headlight warning buzzer is supposed to have a white wire going in (from the headlight switch) and a Red w/TR going out to the ignition switch.

Here's a pic of the buzzer itself, maybe someone can verify what exactly it is. However, this one has a blue wire and a yellow wire going to it.

http://www.savageshooters.net/images/misc/JeepPics/Buzzer.jpg

[tkiller13]

I am going to see if I can find somewhere that can still order custom rattle cans so I can shoot the primered spots as a temp fix. At least then it would all be one color and I wouldn't have to worry about the primer drawing moisture as much.

You can mix you own (custom) spray can colors. If you want pm me and i can tell you how.

[MrFurious]

Evening Update:

Figured out what dang buzzer this is that's now constant when the engine is running...it's the seatbelt buzzer. The "Fasten Seat Belt" light now being on all the time after changing the dash switch got me to looking for that circuit in the TSM diagram, and low and behold the dark blue wire going to it is the same dark blue wire that runs down by the dimmer switch and back under the door sill to the drivers seatbelt retractor. The yellow wire (going off the other side of the buzzer) goes to the seat belt timer, then to the seat belt lamp, and then finally to the Defogger/Heater ground (splice M). Question is....where does this splice actually ground out at under the dash?

Unfortunately I can't see anything in the wiring diagram that would tie this in with the headlights or explain why I have no low-beams.

[shackwrrr]

if you take that blue wire and ground it does the buzzer stop?

[MrFurious]

if you take that blue wire and ground it does the buzzer stop?

In regard to the blue wire, I think I might have found the problem (haven't put the buzer back in yet to verify). Got to thinking about it and the other day I had pulled the sill plate to tuck some speaker wires under the floor mat. Thought maybe, per my usual luck, I may have cut/sliced the wire int he process when reinstalling the sill plate. Sure enough, caught it with the rear screw and bare wire was showing.

Looking at the wiring diagram, it won't matter if I leave the seatbelt buzzer out as the only other thing after it is the dash indicator lamp for the seatbelt.

Back to the headlights....

Looking at the wiring diagram (I almost have it memorized), there are two grey leads that run from the dimmer switch to the headlamps. One's the high-beams and the other is for the low-beams.

The link below is a partial scanned copy of the 78 wiring harness. I have highlighted the headlight circuits in blue to make them easy to find. Maybe someone else can find something obvious that I'm missing.

http://www.savageshooters.net/images/misc/JeepPics/HeadlightHarness.jpg

Dash Switch Wires:
#51 (orange 16) = To Dome/Cargo Lamps
#16 (black 18) = To Dome/Cargo Lamps
#66 (red w/tr 18) = To Fuse Box
#215 (white 16) = To Headlight Warning Buzzer, then power splice C
#18 (white 16) = To Marker/Parking Lights
#12D (red 12) = To Main Dash Power Splice (power splice B)
#15 (red w/tr 14) = To Dimmer Switch (power feed)

Dimmer Switch Wires:
#15 (red w/tr 14) = From Dash Headlight Switch (power feed)
#2 (gray w/tr 18) = To gauge Cluster Connector (feeds brights indicator lamp)
#3 (gray w/tr 14) = To Headlamps
#25 (gray 6) = To Headlamps

Dome lights work fine, so I don't think the problem lies in that circuit.
Marker lights all work, so that circuit should be ok.
Dash indicator light (for brights) works fine, so no problem there.
High Beams work, so one of the two grey wire circuits appears to be good.

One thing I can really see a problem with here is that two power feed sources are shared (splices) with other circuits. This could make troubleshooting a major PITA as if one of the other circuits sharing the power feed is shorted, it could cause the short in the headlight circuit as well. However, since other circuits running off those feeds are working fine (dome lamps, dash indicator light, etc), I am assuming that both are providing the power as they should.

BTW, anyone have a clue what that darn headlight warning buzzer looks like? Noticed mine's not working (may be the problem), but since I can't make it go off I have no clue which thinga-ma-jig it is under the dash.

[MrFurious]

Found the problem finally, not getting power from the dimmer switch to the drivers side headlight plug through the #25 (gray 6) wire. Next question would be: is it just corrosion where the harness plugs into the firewall/fusebox, or does the wire itself have a bad spot in it?

Since I need to dive into it this far, I think I'm simply going to bypass the factory harness (at least the headlight portion of it) and run new wires straight from the dimmer switch to the relays in Jared's harness. This will eliminate the factory wiring from this circuit completely to save me from possible future headaches, and it's only two wires.

I might also tie in the low beam wire to an "ignition on" circuit in the fuse panel so the headlights are on all the time when the vehicle is running, much like all the newer cars are setup. This will only activate the headlights, so the dash switch will still need to be used at night for the marker lights and high beams.

[nograin]

I don't know what your relay package looks like, but the best way to use the relays is as you describe.

On my car (same headlight switch, and dimmer as the Wagon uses), the wiring is also barely adequate (16 and 18 gage). So, I used the original wiring to signal the relays (one for the high beam and one for the low). I put the relays near the alternator, and ran fused feed lines to the relays from the alternator. I used 10 or 12 gage wire and water tight in-line fuse holder from the marine supply store. BTW. All marine supply electrical wire is tin coated copper so its very moisture tolerant.

However, last year I had a problem with the headlights on the wagoneer. That's still got the factory harness setup as the wiring all seemed adequate for the 55/60watt H4s.
Turned out that the wires had chafed against the back of the headlight buckets.