Help with mystery wire identification

[Zeus51]

Ok. For my edification, key on, engine running, service light switch in the up position, headlight switch pushed in. Turn signals and brake lights should be functional.

headlight switch pulled out to first position, all marker lights, turn signals and brakes lights should be functional.

headlight switch pulled out to second position, headlights, all marker lights, turns signals, and brake lights should function

I agree with all of the above. There was a small change since plugging in the cluster.

Service light switch in the up position + headlight switch off : no turn signals or brake lights

Service light switch in the up position + headlight switch ON : constant brake lights, and when I turn on left turn signal it shows that the left indicators on cluster, side markers and rear are all ON constant. Zero flashing. Same for using the right turn signal

I still need to check the rear grounds and clean the turn signal switch. Also wondering if I got a bad turn signal flasher? Could that be causing this?

I don’t have blackout lights attached. Do I need those to complete a circuit?

 

[deank]

Ok. Pictures are revealing.
1. All bulbs must be present in the sockets.
2. If you are able to, put known good bulbs in the front turn signal sockets.
3. The way the system works the cluster bulbs come on solid if a bulb is missing or has a bad element.
4. Need bulbs in all sockets.

 

[Zeus51]

Ok. Pictures are revealing.
1. All bulbs must be present in the sockets.
2. If you are able to, put known good bulbs in the front turn signal sockets.
3. The way the system works the cluster bulbs come on solid if a bulb is missing or has a bad element.
4. Need bulbs in all sockets.

Understood. Will comply and report back

 

[Zeus51]

Ok. Pictures are revealing.
1. All bulbs must be present in the sockets.
2. If you are able to, put known good bulbs in the front turn signal sockets.
3. The way the system works the cluster bulbs come on solid if a bulb is missing or has a bad element.
4. Need bulbs in all sockets.

okie dokie, I installed all the bulbs. Cleaned the turn signal which looked pretty good overall but still cleaned it up. Here’s what we have now.

Service light on, lights off with left turn signal engaged: results in left gauge cluster and front and rear turn signals blinking at normal pace. But no left side marker. But the light supplying light to the voltmeter blinks with the blinker. And the rear right blinks as well.

Service light on, lights off with right turn signal engaged: it results in gauge cluster blinking at normal pace, front turn signal and side marker blinking but no right rear blinking or lights at all

Service light on, lights on and no turn signals engaged: results in constant left turn signal on cluster (not blinking)and right signal on cluster is off, but all lights front and rear (including right side marker) are on but not left side marker.

Service light on, lights on and left turn signals engaged: results in no blinking on cluster just the left cluster signal on constant, no blinking what’s so ever but the lights are on. No left side marker

Service light on, lights on and right turn signals engaged: results in cluster signal blinks at slower pace, no rear blinking, and the front right turn signal and the side marker blink at alternating blinks (not at the same time).

 

[deank]

Ok. Making progress!

Near each headlight there is a ground wire with a bolt. Passenger side is fun because the battery is in the way. Please remove the bolts and clean the bolt, wire connectors and the bolt hole in the radiator support with a wire brush on a drill. These grounds are imperative. All of the lights use these grounds.

For the brake lights, have you looked at the brake light switch by the pedal? The pedal arm must return all the way to push the switch button all the way in. If it does not, adjust the switch closer to the pedal arm until the button is all the way in.

If the cluster left turn signal light stays on solid there is a bulb problem on the right side of the truck.

If the cluster right turn signal stays on solid there is a bulb problem on the left side of the truck.

The grounds for the rear are on both frame rails, they will probably need cleaning too.

 

[Zeus51]

Ok. Making progress!

Near each headlight there is a ground wire with a bolt. Passenger side is fun because the battery is in the way. Please remove the bolts and clean the bolt, wire connectors and the bolt hole in the radiator support with a wire brush on a drill. These grounds are imperative. All of the lights use these grounds.

For the brake lights, have you looked at the brake light switch by the pedal? The pedal arm must return all the way to push the switch button all the way in. If it does not, adjust the switch closer to the pedal arm until the button is all the way in.

If the cluster left turn signal light stays on solid there is a bulb problem on the right side of the truck.

If the cluster right turn signal stays on solid there is a bulb problem on the left side of the truck.

The grounds for the rear are on both frame rails, they will probably need cleaning too.

Thanks! Both front clip grounds on driver and passenger side of radiator have been sanded and cleaned.

I actually replaced the brake light indicator. But it’s possible it’s not the right one despite the stores description.

The cluster light on constant confuses me. So it indicates the opposite side light? I’ve tested bulbs and can make the right markers blink sometimes but the left cluster light stays on constant. What would you change on the right side marker?

I plan to clean the rear grounds this weekend. Any other advice you can think of would be great. I really appreciate your time with this.

 

[deank]

I think for now, focus on the grounds.

 

[ehuppert]

If i recall correctly there's also ground wires in rear between light housing assemblies and body

 

[deank]

If i recall correctly there's also ground wires in rear between light housing assemblies and body

Good catch. There is a ground for the trailer connector also. Thanks!

 

[deank]

There is another ground that you might take a look at. Under the dash above the parking brake is the only ground in the cab. It looks like a six-legged spider with one one wire clamped under it. Clean those components really well also.

After that you only 4 more grounds left on the truck.
1. Ground for blower motor
2. Engine to cab ground behind the resistor cover and passenger side rear of the engine
3. The 24v ground from the bus bar to the passenger side rear of the engine
4. 12v frame ground on the frame near the lift pump

There may be one more for the wiper motor

I think you already did the ones for the blackout lights.

 

[deank]

Re-reading your posts, I think you are hoing to have to do some continuity checks. It sounds like you do have some wires crossed somewhere.

It helps me to draw a checklist of where each bulb socket pin terminates at the connector and check it off as I go, then test it against all other pins to verify no continuity on other wires.

You are going to need a long wire to reach from the corners of the truck to the cab.
Will need to disconnect the batteries first.
if you have a test lead with alligator clips it will help a lot. Using the wiring diagram test each wire from each bulb socket to the harness under the steering wheel where the turn signal switch connects. Then, check that same wire to every pin on the connector. If there is continuity on any other connector pin there is a problem.

Edit! And check every wire against ground also!

If by some miracle all the wires check out it will be the turn signal switch.

However, if you have another turn signal switch you could “dry hang” it to test sll with power again.

Sorry for being long winded…

 

[Zeus51]

Re-reading your posts, I think you are hoing to have to do some continuity checks. It sounds like you do have some wires crossed somewhere.

It helps me to draw a checklist of where each bulb socket pin terminates at the connector and check it off as I go, then test it against all other pins to verify no continuity on other wires.

You are going to need a long wire to reach from the corners of the truck to the cab.
Will need to disconnect the batteries first.
if you have a test lead with alligator clips it will help a lot. Using the wiring diagram test each wire from each bulb socket to the harness under the steering wheel where the turn signal switch connects. Then, check that same wire to every pin on the connector. If there is continuity on any other connector pin there is a problem.

Edit! And check every wire against ground also!

If by some miracle all the wires check out it will be the turn signal switch.

However, if you have another turn signal switch you could “dry hang” it to test sll with power again.

Sorry for being long winded…

Thanks for the help! I still need to clean the rear grounds this weekend. As a recap I have:
Cleaned Grounds at: driver and passenger side of radiator, spider in cab, engine to firewall, new cables from busbar outward To batteries and engine ground. And brake lights housing grounds.

I have also cleaned the dimmer switch, turn signal connector.

I did replace the side marker bulb connectors and therefore have a question. Is there a ground side and hot side to those two wires going to the buld socket? Looking at the attached diagram, it looks like the Lt Blue wire on left indicator goes to ground side? Is that how that is read? I got to worrying that I cross wired them when I changed them.

Another question is do the BO light circuit influence the service light circuit?

This weekend, I will start on cleaning all remaining grounds and probably breaking down the steering column to see if it’s the switch. I also still have no brake lights and I have changed the brake light indicator.

 

[deank]

On post#24 second paragraph, with left turn engaged all of the left side turn signals(front and rear) and the marker does not work, but, the right rear turn signal works? As well as the backlight for the 24 volt meter? There are wires crossed somewhere…

in the turn signal switch the front and rear lights have separate circuits because the brake lights go through the turn signal switch. If you are getting a rigt rear turn signal and left rear turn signal when the switch is set to left turn there is definitely some wires crossed Or possibly a bad switch - plastic can turn to dust and allow contacts to touch.

 

[Zeus51]

On post#24 second paragraph, with left turn engaged all of the left side turn signals(front and rear) and the marker does not work, but, the right rear turn signal works? As well as the backlight for the 24 volt meter? There are wires crossed somewhere…

in the turn signal switch the front and rear lights have separate circuits because the brake lights go through the turn signal switch. If you are getting a rigt rear turn signal and left rear turn signal when the switch is set to left turn there is definitely some wires crossed Or possibly a bad switch - plastic can turn to dust and allow contacts to touch.

I am starting to agree with you. I think using your “complete the circuit first” mentality, I’m going to clean or replace switches that might be problematic and then start tracing continuity for crossed wires. and that brings us to todays questions:

headlight switch: see pics but both my old and new switch has seven spades to connect to but my electrical connector that plugs into it only has 6. Does everyone else have seven connectors in their plug? Am I missing a wire somewhere?

grounds: inside the driver side of the cab, the spider, based on forum posts and electrical diagrams, there should be multiple ground wires going to it. Does everyone else have home run ground wires going to this spider? Or are there splices along the way in the circuit that results in just one main ground wire going to the spider? Bc that’s what it looks like I have.

grounds: i have been studying the sticky on ground locations. I cleaned both sides of radiator grounds, the frame to radiator side ground, the trailer ground on the rear crossmember, the spider inside the cab. Are there Suppose to be any frame rail grounds toward the center or rear of the m1009? Mine don’t have any but I use to have a m1008 that did.

As always, thank you for your assistance as i slowly work through this.

 

[deank]

Only six wires on the headlight switch.
I only have one wire to the spider also.

 

[Zeus51]

Only six wires on the headlight switch.
I only have one wire to the spider also.

Thats good to know. I am really dreading the wire tracing and continuity testing. But it is lookin like the only way.

 

[Zeus51]

On post#24 second paragraph, with left turn engaged all of the left side turn signals(front and rear) and the marker does not work, but, the right rear turn signal works? As well as the backlight for the 24 volt meter? There are wires crossed somewhere…

in the turn signal switch the front and rear lights have separate circuits because the brake lights go through the turn signal switch. If you are getting a rigt rear turn signal and left rear turn signal when the switch is set to left turn there is definitely some wires crossed Or possibly a bad switch - plastic can turn to dust and allow contacts to touch.

Update!! Ok. I have changed switches like: turn signal switch in the column, brake light indicator, headlight switch,

Changed relays behind the cluster taped to the top of the dash, two relays beside the Doghead relay, new flasher relay, new turn signal relay

All new fuses. And fuse box was cleaned

Cleaned grounds at: left and right of radiator, the radiator to frame, spider in the dash, L and R brake light housing, the trailer connector ground in rear crossmember, new busbar to engine cable, changed the engine to cab strap,

I still haven’t cleaned the blower ground, horn self ground? I don’t see on either of these where I’d do that?





Also, this is where the service light situation is at the moment.

Service light on, lights off with left turn signal engaged: results in left gauge cluster and front turn signal blinking at normal pace. But no left side marker. But the light supplying light to the voltmeter blinks with the blinker. And the rear right blinks as well.

Service light on, lights off with right turn signal engaged: front turn signal and side marker blinks at normal pace no right rear blinker.

Service light on, lights on and no turn signals engaged: all four corners turn on except front left side marker

Service light on, lights on and right turn signals engaged: all lights stay on but now the right signal indicator blinks opposite of the right side marker. Rear right does not blink

Service light on, lights on and left turn signals engaged: all lights on. Turn signal stays solid. Right side marker is off.

Under all circumstances the front left side indicator stays off. I have changed this bulb socket twice bc I thought I crossed my wires but I’ve tried it both ways and it’s currently wired so I produced a positive voltage on my meter. So I feel good that positive is to positive and ground is to ground.


What am I missing? How do I clean the blower, horn and other self grounding locavtions?

 

[deank]

The blower motor grounds through the box it is mounted to. Most times the members here will tell you to run a second ground from the blower motor to another ground point (negative bus bar). That is what I did.

the horn is self grounding by the mounting bolt, just remove the horn and clean the bolt, horn where it bolts on and the point on the radiator support where it bolts on.

can you do a continuity check through the left side marker? All lights and power off, check continuity through both wires with the bulb in place.

I am still pondering all the light issues. I will get back to you on those.

 

[deank]

I have been reviewing the wiring diagrams. The voltmeter light is strange, but as it is supposed to be connected to the light for the heater control also, please see if it is blinking as well. Power for that circuit comes from the light switch to the bottom left fuse then provides power for all of the backlighting in the cluster.

Front and rear turn signals have separate circuits. They do not cross.

All four front turn signals/marker bulbs all share the Brown -9A that brings power from the headlight switch.
The front left turn/markers share LT Blue-14A that goes to the left turn indicator in the cluster to the turn signal switch back out on Brown -27 to the flasher at the top left of the fuse box

Thee right front turn/markers do the same thing but use DK Blu-15A

 

[deank]

All of the rear lights share BRN-9A for power.

There may be one weak point in all of this, the fuse panel itself with the bulkhead connector. Have you done anything to take it all apart and clean all the contacts and tighten up the fuse connectors? I have completely gone through the whole thing on mine and found several fuse holder contacts that had to be adjusted.