83 720 electrical gremlins tied together?

[cubetop]

Ok. I've searched around on the forums and couldn't really find what I'm looking for. I know I'm going to have to get a manual now but had a few basic questions.

 

For a primer, I have a 83 720 2wd 5sp KC. Just trying to track down a few electrical gremlins.

 

1) Headlights - Passenger side work fine. Drivers side low beam is dimmer but useable. Switch to high beams and passenger side work fine, driver's side go out. - Thinking bad grounding. Found at least one grounding braid that wasn't connected to anything. I know I'm going to be adding some ground straps.

 

2) Dash - No fuel or temp gauge. Ground the sending unit, no movement. - Bad voltage regulator? (Can one be bought? Any help with a part number?)

 

3) Dash - No gauge lights. Poor radio harness was butchered. Removed the "butchering." Have some wires not connected to anything. I know the cigarette lighter wires and have them seperated. Have a black/blue wire (ground I think) also have a red/yellow and a red/blue. If I touch the red/yellow, I'll get dash lights but when I turn headlights on, dash lights go back out. Do the dash lights pass through the radio or something because I think those wires are for the radio.

 

I have checked my fuse panel and everything is in working order.

 

Trying to get as much done in the electrical before I start the other stuff. (She's getting an engine swap in the near future.....KA24E or DE, I'm not sure yet but leaning towards a E.)

 

Thank you for any guidance or knowledge. Interior is already disassembled. Dash it out of the truck so checking anything or removing anything is easy in the gauges.

[MicroMachinery]

Get a legitimate wiring diagram and see if any of these systems have a common point. Start looking there, then work your way to the problem itself.

[cubetop]

Yarp. That's what I'm working towards. Was hoping maybe a 720 guru would chime in with any helpful tips or words of encouragement. I WILL make this a whup ass little truck eventually!

[wayno]

Ok, you must understand this, there is no headlight ground on the headlight side of the headlight relay, the high beam indicator is not even grounded in the instrument cluster, the only ground is at the relay away from the headlight circuit itself, the relay is on the fuse box, if you ground any of the headlight wires, nothing is going to work right.

I have been through this when using a 720 wiring harness in my 521KC diesel truck, and I got to know the headlight circuit ins and outs pretty good, as I also had to figure out how to wire the headlights themselves, as 720s have square headlights, and 521s have round headlights, one would think you would just plug them in, but it don't work that way, as it turns out that the round and square headlights are wired differantly.

First thing I would do is cycle the 4 way switch a whole bunch of times, this switch is tied into a lot of things, next thing to check/replace is the headlight relay on the fusebox, your headlights will actually work without it, but as I remember, default is the highbeams.

If even one wire was cut and connected a differant way your screwed, lets say you put fog lights on your truck and tied it into the highbeam headlight circuit, and wired it so power went to the fog light, and then to ground, you just introduced a ground into the headlight cicuit, nothing will work properly now.

The headlight circuit is a stand alone mini harness.

 

The black wire with the blue line is a ground wire.

 

The photo below shows a little knob on the bottom of the dash, this controls the dash lights, every wire has to be connected for them to work properly, it has 3 wires, red/yellow, red/blue, and black.

[cubetop]

You sir, are my hero. My "dashlight dimmer" switch is hooked up and all the wires are there. Poor harness was monkeyed with at the radio it looks like BUT there's probably some other shenanigans going on in there. I was looking / hoping for a common point between all the problems but the reality is that there's multiple faults here. *sigh* I have my work cut out for me for sure.

 

I appreciate your time and input.

 

I wasn't aware of the no ground on the lights. From what I had been told was that if there are missing grounds in the engine bay, you are in for all kinds of weirdness like dim lights, etc since hte path is no longer closed. I'll double check the headlight relay and will TRY to pull the switch off so I can properly clean the contacts though it seems it work properly since hte passenger side headlights are functioning correctly.

[datzenmike]

 

For a primer, I have a 83 720 2wd 5sp KC. Just trying to track down a few electrical gremlins.

 

2) Dash - No fuel or temp gauge. Ground the sending unit, no movement. - Bad voltage regulator? (Can one be bought? Any help with a part number?)

 

If your back up lights work or the red brake light works in the dash then the fuse is fine for the in dash volt regulator. If they are not working check/replace the 15 amp fuse the 4th one over from the left side of the box. I would assume the volt regulator is bad. I think it's located in one of the gauges. On the 620 it's in the temp gauge, maybe the 720s are the same?

 

 

3) Dash - No gauge lights. Poor radio harness was butchered. Removed the "butchering." Have some wires not connected to anything. I know the cigarette lighter wires and have them seperated. Have a black/blue wire (ground I think) also have a red/yellow and a red/blue. If I touch the red/yellow, I'll get dash lights but when I turn headlights on, dash lights go back out. Do the dash lights pass through the radio or something because I think those wires are for the radio.

 

I have checked my fuse panel and everything is in working order.

 

Is the controle plugged in?

Is the control turned full right?

Red/Yellow stripe is power from the lighting switch. Red/Blue wires go back to the dimmer from the dash bulbs to be grounded through the dimmer. The dimmer varies the resistance to ground to dim the lights.

[cubetop]

If your back up lights work or the red brake light works in the dash then the fuse is fine for the in dash volt regulator. If they are not working check/replace the 15 amp fuse the 4th one over from the left side of the box. I would assume the volt regulator is bad. I think it's located in one of the gauges. On the 620 it's in the temp gauge, maybe the 720s are the same?

 

 

 

 

Is the controle plugged in?

Is the control turned full right?

Red/Yellow stripe is power from the lighting switch. Red/Blue wires go back to the dimmer from the dash bulbs to be grounded through the dimmer. The dimmer varies the resistance to ground to dim the lights.

 

The "brake" idiot light does work and all fuses have been checked and are good. Voltage regulator it is! I'll pull the gauges tonight and give them a good cleaning and check things out.

 

As for the dimmer circuit.......I missed a part. If I touch the red/yellow to 12V I get dash lights but they go out as soon as I turn on the headlight switch. That's what I SHOULD have said.

 

I have moved the switch in either direction but I don't have dash lights unless I do what I described above. The dimmer switch is hooked up and appears to be untouched. The red/blue is at the radio harness so is the black/blue and the red/yellow. That's why I was wondering if it all feeds back through the radio in a loop. I'll try to tie the black/blue back into a ground but I'm not sure what to do with the red/yellow and red/blue. It was just weird that I could get the dash lights to work if the headlights were off if I took the red/yellow to 12v. I definitely need a good wiring diagram. I'll be looking.

 

Again, I appreciate your time and effort. It's probably a simple thing from here.

[cubetop]

Fuel Gauge is fixed! Took the cluster apart and got the Fuel Gauge out. Simple circuit, not much to fail so I cleaned the spring contact with some very fine sand paper. Plugged in and works fine. Temp Gauge still no worky but I'm almost 100% certain it's the sending unit.

 

1 down!

 

Going to try to reconnect the red/blue, red/yellow, and black/blue today and see if I can get dash lights.

 

I replaced the headlight relay. It made the driver's side low beam a bit brighter, still no high beams though. When you hit the switch, the low beam gets REAL dim like almost on. I'll try to tackle that switch soon. I haven't looked but I'm assuming I have to pull the steering wheel off to get the switch off.

[ggzilla]

Yes, that sounds like a ground problem. The headlights must have 12V and ground, or they don't work. If it is grounded via a relay, there is still a ground connection somewhere. If it is corroded or loose, the circuit will find some other way hence the dim, low light.

[cubetop]

Yar. I'll be diving in again today or this weekend. Getting married soon so running out of time for stuff until after. Little piece at a time and it'll get done.

[datzenmike]

Fuel Gauge is fixed! Took the cluster apart and got the Fuel Gauge out. Simple circuit, not much to fail so I cleaned the spring contact with some very fine sand paper. Plugged in and works fine. Temp Gauge still no worky but I'm almost 100% certain it's the sending unit.

 

1 down!

 

 

Ground the temp sender wire (Yellow/Black stripe) on the intake near the thermostat? The gauge should go to HOT. If it does but does not when the motor is hot then yes, the sender is bad. (very rare) Maybe the wire is loose or the contact bad?

[cubetop]

Ground the temp sender wire (Yellow/Black stripe) on the intake near the thermostat? The gauge should go to HOT. If it does but does not when the motor is hot then yes, the sender is bad. (very rare) Maybe the wire is loose or the contact bad?

 

the wire was actually off and dangling when I got the truck. I put it back on but no go. HOWEVER, it could just be REALLY dirty and not making contact. I'll be digging into it HOPEFULLY today after work. (Was gonna do it last night but got roped into making dinner.)

[cubetop]

I have dash lights now.

 

So there are 2 sets of wires. On the dimmer switch there is black/blue(ground), red/yellow, red/blue. At the radio harness, which is CUT, there is black/blue, red/yellow, red/blue also. Both reds go to 12V when the headlight switch is on, same as at the dimmer switch. I tied the cut red/blue to the black/blue and VOILA! Dash lights. Dimmer switch is not functioning but at least I can drive in the dark now without wondering how fast I'm going.

 

Baby steps. I'll get it right! I found schematics but they are a tad vague.

[ggzilla]

Nice progress.