Electrical nightmare, 1968 cluster lights, parking lights, horn, etc.

[Crazy73]

The following electrical gremlins have been torturing me for over a month now, and I've been searching out old threads for research and troubleshooting but I'm finally stumped and starting a new thread.

1. I can't get the instrument cluster to illuminate in a 1968 Rallye Dash --- 4-17-17 I'm an idiot and was turning the knob the wrong way, fixed.
   
2. Parking/running lights illuminate in position 1, then the front signal bulbs go very dim when position 2 turns on the headlamps. --- 4-17-17 it was a bad flash pot (new electronic 2-post type w/ a ground wire).
   
3. Turning the rheostat occasionally changes the brightness of the parking lamps, but they are never "bright" when headlamps are on, regardless of signal lever position. --- 4-17-17 fixed with new flash pot.
   
4. Horn intermittently works, the volume varies --- 4-15-17 fixed with forcing better grounds at horns & column.
   
5. Signal lights were previously not working but that was fixed this morning with a new cam

------1st Issue details------can't get the instrument cluster to illuminate in a 1968 Rallye Dash
-All bulbs are new, no difference with swapping the OEM bulbs for LED
-All the gauges function properly
-Signal indicators in the dash work.
-I have added extra grounds to the cluster, dash, steering column, and at the parking lamps.
-There is power on the orange wire at the cluster (clock connector) and at the fusebox. Power reads only 6V, is that normal for the gauges?.
-All the connections are good and clean
-No [aftermarket] splices or burn through in the under-dash harness

------2nd Issue details------Parking/running lights illuminate in switch position 1, then the front signal bulbs go very dim when position 2 turns on the headlamps
-All bulbs are new, no difference with swapping the OEM bulbs for LED
-Hazards work when headlamps are off or in park.
-Flash pots are both new
-I have added extra grounds to the cluster, dash, steering column, and at the parking lamps.
-Brake lights and rear signal lights function properly in any switch position.
-All the connections are good and clean
-No [aftermarket] splices or burn through in the under-dash harness

------3rd Issue details------front parking/running lamps are not bright when headlamps are on
-Headlamp switch is a new NAPA unit. 3 original light switches/rheostats made no difference with the instrument lights.
-I have replaced the signal cam
-Brake lights and rear signal lights function properly in any switch position.
-All the connections are good and clean
-No [aftermarket] splices or burn through in the under-dash harness
-Forward light harness/engine bay wiring is all new and properly grounded.

------4th Issue details------Horn intermittently works, the volume varies
-Horns were bench tested and work
-Horn relay is new and works (audible when button is pressed), possible bad ground at horn?

 

[RedFish]

Does it add up? Headlight switch has 2 power supplies to it, B1 and B2. B1 shouldn't take power away from B2 unless there isn't enough power to begin with. Illumination dimmer shouldn't take away from/effect park lamps either unless B2 is suffering low voltage.
So lets go back to the trunk of the tree... A big black wire leaves the ALT gauge. Then it has a factory weld splice where branches go to various places ( so no splices isn't exactly true ) .
One branch goes to headlight switch B1. Another goes to the fuse box to power a buss bar where the hot at all times circuits are supplied. I believe there is a voltage drop in this somewhere.
There is also a branch to the ignition switch. With ign' switch on this feeds a wire to another buss bar in the fuse box. Turn signals, blower, wipers, and more are here. If none of these circuits suffer low voltage, thats good. I suppose I would drop the fuse box, pic the back cover off and have a good look at both sides. Just crusty fuse clips can cause voltage drop.
Since you mentioned the inst' panel... there are 2 connectors with a orange wire in each. 2 illumination bulbs per wire. This is where we get "only 1 half of my panel is lighted" threads. I don't read that you have that problem. I don't read blowing fuses either.
I have to ask though... About that round panel connector, have any of those female terminals been out of it? Another owner once read the factory diagram wrong, put the wires in the wrong positions and had all kind of screwed up electrical. Why their engineer decided to rotate this connector 90 degrees on paper is still a mystery to me. Regardless the orientation on paper, the locating key in the center dictates wire positions ( it was drawn correctly ). That owner needed only to move his beer and rotate his drawing 90 degrees LOL
last 2 paragraphs are probably TMI Get factory wiring diagrams, study B2 Good luck

 

[Crazy73]

Does it add up? Headlight switch has 2 power supplies to it, B1 and B2. B1 shouldn't take power away from B2 unless there isn't enough power to begin with. Illumination dimmer shouldn't take away from/effect park lamps either unless B2 is suffering low voltage.
So lets go back to the trunk of the tree... A big black wire leaves the ALT gauge. Then it has a factory weld splice where branches go to various places ( so no splices isn't exactly true ) . One branch goes to headlight switch B1. Another goes to the fuse box to power a buss bar where the hot at all times circuits are supplied. I believe there is a voltage drop in this somewhere.

OP edited to specify no aftermarket splices. I'll dig around the switch a bit, test for power there, and trace those wires out according to the diagram.

There is also a branch to the ignition switch. With ign' switch on this feeds a wire to another buss bar in the fuse box. Turn signals, blower, wipers, and more are here. If none of these circuits suffer low voltage, thats good. I suppose I would drop the fuse box, pic the back cover off and have a good look at both sides. Just crusty fuse clips can cause voltage drop.

The fuses for the turn signals, blower, wipers, etc are all at 11.7-12.2V - The only one not in that range is the instrument cluster, which is around 6V.

I cleaned all of the fuse clips a few weeks ago and replaced all the fuses with new ones.

Since you mentioned the inst' panel... there are 2 connectors with a orange wire in each. 2 illumination bulbs per wire. This is where we get "only 1 half of my panel is lighted" threads. I don't read that you have that problem. I don't read blowing fuses either.

Correct, neither side illuminates, both orange wires have power.

I have to ask though... About that round panel connector, have any of those female terminals been out of it? Another owner once read the factory diagram wrong, put the wires in the wrong positions and had all kind of screwed up electrical. Why their engineer decided to rotate this connector 90 degrees on paper is still a mystery to me. Regardless the orientation on paper, the locating key in the center dictates wire positions ( it was drawn correctly ). That owner needed only to move his beer and rotate his drawing 90 degrees LOL
last 2 paragraphs are probably TMI Get factory wiring diagrams, study B2 Good luck

I have no idea if they have been removed from the clock or not over the last 49 years (I sure haven't pulled them out), but I will double-check that the orange wire does line up with the pin to illuminate the cluster.

 

[RedFish]

You wouldn't be the first to find fault in the backside of the fuse box. Those females aren't locked, boxes get water in them from leaks, etc...
Your dimming park lamps and dimmer rheostat varying park lamps is my focus. That just shouldn't happen if everything gets 12 volts through solid connections.
If bulkhead, fusible link, ALT' gauge was the culprit, every dang thing would suffer low voltage, more circuits turned on would take away from other circuits.
Current will take the best path or path of least resistance to ground. The path through the wiring and elements in headlight bulbs is a lot better than through those smaller wires and bulbs.
That still suggests low voltage/amperage everywhere. Are you testing with battery only or with active charging system or both ? Do results change?

 

[moparmat2000]

Check your rheostat on the headlamp switch, and or mod the cluster to used 5630 led strip lighting inside the housing. Cheap and easy mod.

Your horns may have a bad or weak ground. Try unbolting the horn and cleaning the mount bracket and bolt.

Heres pix of the dimmable 12V 5630 LED peel and stick flexible strip lighting mod to my 67 rallye cluster. The factory backlighting sucks actually. Only 4 bulbs, lots of bright and dim spots. The illumination on the pix is with a 9v battery. These use very little voltage to illuminate. Lots of different colors to choose from, or use tri color strip, and you can fine tune it to whatever color you want. I chose green, and soldered wires into a bulb socket. Its polarity sensitive, so if it doesnt light, switch the leads.

Hope this helps
Matt

 

[rays266]

60s and 70s mopar electrical engineering is a good education of automotive technology for the 40s and 50s

 

[Crazy73]

After getting out the dremel and forcing a better ground the horn now works a bit more reliably (but only when the ring is pressed to one side, I get nothing the other way).

Tomorrow I'll crawl under the dash again and monkey around with the fuse box and a test light/vm.

 

[moparmat2000]

Take the horn ring off the steering wheel and remove the horn contactor, clean up the horn contactor where it has to be pushed together to close contact. Its probably dirty or got surface rust.

Look for the easiest stuff first. The body is the ground return. Check grounds, and check fuses, and corroded contacts.

 

[Crazy73]

Take the horn ring off the steering wheel and remove the horn contactor, clean up the horn contactor where it has to be pushed together to close contact. Its probably dirty or got surface rust.

Look for the easiest stuff first. The body is the ground return. Check grounds, and check fuses, and corroded contacts.

Yes, I cleaned the sets of contacts in the steering wheel and on the horn ring when I had it apart for the turn signal cam replacement. Maybe adding a ground from the column to the body will help?

 

[moparmat2000]

There is supposed to be one there from the factory. About 3 inches long with 2 ring terminals on it. Comes off one of the bolts that hold the column support to the column under the dash and bolts right to one of the studs that hold the column up right next to the column support.

 

[Crazy73]

I'm an idiot and thought the dimmer switch operated clockwise to brighten the dash lights, while it operates counter-clockwise to increase illumination Dash lights work and dim properly, horn works (pressing on right side of horn ring) with improved grounds & cleaned contacts.

Now my ammeter doesn't work at all. Maybe I overtightened a bolt for the large red/black wire, glad I have an extra gauge.


Also, the high beam indicator is very faint (almost no illumination) - I'll be checking the high-beam switch on the floor later today.

 

[moparmat2000]

If high beam is faint but high and low beams work, its prob a bad ground from the bulb socket to the circuit board. Ditch the ammeter, and attach the 2 ammeter wires together and shrink wrap. That thing is a fire hazard anyways.

When the turn signal indicator bulbs dimly stay lit when not in operation sometimes thats the sign of a weak ground and power back feeding thru the bulb. Make a good solid external ground wire from the back of the cluster housing to the dash frame. That should help with some of the gremlins.

 

[Crazy73]

If high beam is faint but high and low beams work, its prob a bad ground from the bulb socket to the circuit board.

Thanks, I'll check the removable bulb mount, one of the legs might be bent. That bulb is tough to get to with the cluster in the dash! When I had the cluster out a few days ago I cleaned all the copper connections on the boards to ensure a good contact patch.

Ditch the ammeter, and attach the 2 ammeter wires together and shrink wrap. That thing is a fire hazard anyways.

When the turn signal indicator bulbs dimly stay lit when not in operation sometimes thats the sign of a weak ground and power back feeding thru the bulb. Make a good solid external ground wire from the back of the cluster housing to the dash frame. That should help with some of the gremlins.

Yes, I added several grounds from the cluster housing to the frame & column when I installed a new cam switch and the signal indicators are fine.

The front parking/signal lights going dim with HL operation has also been fixed, the electronic flash pot was bad - I swapped over the flash pot from the hazards and now they illuminate properly.

 

[moparmat2000]

Should concider converting your ammeter to volts. Theres a few threads on here for this including pn# for the aftermarket sun volt gage needed to do this. I converted mine. You have to grind out a spot in the cluster housing so the needle gets full swing, and you reuse your original ammeter face. I also reused my ammeter needle too. I clipped the plastic needle off leaving a small space to glue the ammeter needle in place so it looks original.

You ream out the hole in the gage cluster housing for the + stud on the volt gage, insulate the + stud hole with a plastic grommet and plastic washers. The negative stud you ground right to the gage cluster housing with steel washers b and a nut. Then run a short wire from the 12v + stud off the volt gage to the 12v gage cluster feed stud off the back of the fuel gage.

 

[moparmat2000]

I added a fault light. However i'm running a denso late model alternator. This makes wiring this up easy. Also the black ground wire i eliminated as it was redundant, and just - case grounded the gage.