Park/side marker lamp problem

[Rockstomp]

Howdy folks! You might guess that I am a rank amateur at the electrical stuff, sooooo, I'm going to swallow my pride and ask for help. I have head lights, but no tail lights. I have signal indicators and dash indicator lights, but no instrument lamps. My park/side marker lamps won't come on, either. I changed the switch and no luck. I've watched one video after another on how to find a short, but that does me no good. I need real help. How do I figure out what's happening? HELP!!! I have a multimeter and a test light. Fire away, I'm all ears.

 

[Don5]

You need help from @chengny . He is the man when it comes to chasing wiring bugs. It does sound like a ground problem to me- especially the rear lights and park lights. You did check the fuses right?

 

[chengny]

I have head lights, but no tail lights.

Brake lights? The above makes sense because (even though the power to each circuit passes through the headlight switch) the H/L circuit is segregated from the parking lamp circuit. The H/L's are protected by a fusible link on the firewall. The tail lights/front parking (and front side markers)/courtesy lighting are protected by a fuse in the main fuse block (TL/CTSY).


Here, let's do it this way:

Check for voltage at the fuse socket labeled INST LPS (top fuse, 2nd column from right). The line side should be the left clip - but check both sides.

If you have no voltage there, read this:


The reason the fuse socket is dead for the panel lighting is because there is no power coming back from the rheostat in the HL switch.

The flow goes like this:

The red 3.0 wire from the firewall fusible link is tied into the line side of the far left column (looking forward). The actual connection is in the lower half, there is a shunt about halfway up that supplies the sockets in the upper half. These sockets are for various options (clock, cargo light, etc) that require constant battery power.

Power comes out of the TL/CTSY fuse and up to the HL switch on the .8 orange lead. The voltage is reduced as needed by the rheostat, and is lead out of the HL switch at pin 44. It goes back to the fuse block (from the HL switch) on the 1.0 green lead. The tail light power does not pass through the rheostat (just goes through a switch).

That 1.0 green lead is tied into the fuse block at the hot side of the 5A Inst Pnl fuse. The load side of the fuse is connected to the panel illumination lighting via a .5 gray wire.

Probably the easiest place you can start ringing this out at the HL switch:

Power in to the rheostat on the .8 orange at pin 40 but no power out on the 1.0 dk green at pin 44? Bad rheostat.

Power at pin 44 but not at the line side of the instrument light fuse? The green 44 wire is broken/disco'd.

If there is no power into the rheostat on the orange wire, check the load side of the TL/CTSY fuse. Power there? Broken orange lead from the fuse block to the HL switch.


Here is the dwg that goes with the description of the circuit (above):

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[johnnydefacto]

I have head lights, but no tail lights.

Brake lights? The above makes sense because (even though the power to each circuit passes through the headlight switch) the H/L circuit is segregated from the parking lamp circuit. The H/L's are protected by a fusible link on the firewall. The tail lights/front parking (and front side markers)/courtesy lighting are protected by a fuse in the main fuse block (TL/CTSY).


Here, let's do it this way:

Check for voltage at the fuse socket labeled INST LPS (top fuse, 2nd column from right). The line side should be the left clip - but check both sides.

If you have no voltage there, read this:


The reason the fuse socket is dead for the panel lighting is because there is no power coming back from the rheostat in the HL switch.

The flow goes like this:

The red 3.0 wire from the firewall fusible link is tied into the line side of the far left column (looking forward). The actual connection is in the lower half, there is a shunt about halfway up that supplies the sockets in the upper half. These sockets are for various options (clock, cargo light, etc) that require constant battery power.

Power comes out of the TL/CTSY fuse and up to the HL switch on the .8 orange lead. The voltage is reduced as needed by the rheostat, and is lead out of the HL switch at pin 44. It goes back to the fuse block (from the HL switch) on the 1.0 green lead. The tail light power does not pass through the rheostat (just goes through a switch).

That 1.0 green lead is tied into the fuse block at the hot side of the 5A Inst Pnl fuse. The load side of the fuse is connected to the panel illumination lighting via a .5 gray wire.

Probably the easiest place you can start ringing this out at the HL switch:

Power in to the rheostat on the .8 orange at pin 40 but no power out on the 1.0 dk green at pin 44? Bad rheostat.

Power at pin 44 but not at the line side of the instrument light fuse? The green 44 wire is broken/disco'd.

If there is no power into the rheostat on the orange wire, check the load side of the TL/CTSY fuse. Power there? Broken orange lead from the fuse block to the HL switch.


Here is the dwg that goes with the description of the circuit (above):

You must be registered for see images attach

thank you thank you. I wish I had seen this before, I have been searching this site and others to try to help me with my t/l ctsy fuse blowing problem. I finally noticed today that my 5amp INST/LAMPS fuse (was not blown) but did not have power to the supply side. That lead me to this post.

I pulled out every running light bulb, and disconnected the rear lights at the harness hoping the fuse would not blow when I pulled out the headlight/running light switch. No luck. I stll need to disconnect the instrument cluster to see if the short is in there, but before I do that, I have a new headlight switch on the way. You said the rheostat in the switch is bad if my dk green wire to the 5amp fuse is dead, I ordered a complete new switch, i presume the restate is built into the switch (in front where you can see as the knob turns). If the rheostat is changed and I get power to the green wire, will this be the reason my t/l ctsy fuse keeps popping?

thanks,

 

[chengny]

hoping the fuse would not blow when I pulled out the headlight/running light switch. No luck.

If that's the case - that the fuse doesn't blow unless the H/L switch is pulled out (to either the parking or head lights position), you can eliminate the entire courtesy lighting circuit as the problem. The position of the H/L switch has no effect on the power to the courtesy lighting circuit. Since the fuse only blows when the H/L switch is operated, the wiring problem must be in either the front or rear parking light circuits (i.e. the 9 BRN)

The 40 orange circuit is always hot from the fuse block (20 amp T/L CTSY fuse). It first runs up to the H/L switch and is connected at terminal 5:

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At the terminal it enters the switch and provides power to the tail lights and front parking lights whenever the H/L knob is pulled out. The 9 BRN circuit starts at terminal 4 on the H/L switch:

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So you have two possible general areas where the problem might exist: the front lighting part of 9 BRN and the rear part.

You disconnected the rear wiring harness as a test and the fuse still blew. In a way that's good - you eliminated all the wiring associated with the rear tail lights, side markers and license plate lights. The only place there could be a short/ground would be in the single lead that runs from the firewall transit to the rear lighting harness plug:

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Unless your exhaust has been modified or work has been done on the frame recently, it's probably a good bet that the problem is not on that single lead from the FW to the plug. I would move on to the front lighting.

There are 6 light assemblies in the front end that are served by the 9 BRN wiring. The two combination parking/directional lights, two dedicated parking lights and two marker lights:

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You should check each of them - and all the interconnected wiring. It might be easiest to unplug every light assembly that has a 9 BRN lead connected to it. Then, with them all unplugged start reconnecting them one by one. If the fuse blows when a particular light is plugged back in check the socket for shorts.

 

[johnnydefacto]

hoping the fuse would not blow when I pulled out the headlight/running light switch. No luck.

If that's the case - that the fuse doesn't blow unless the H/L switch is pulled out (to either the parking or head lights position), you can eliminate the entire courtesy lighting circuit as the problem. The position of the H/L switch has no effect on the power to the courtesy lighting circuit. Since the fuse only blows when the H/L switch is operated, the wiring problem must be in either the front or rear parking light circuits (i.e. the 9 BRN)

The 40 orange circuit is always hot from the fuse block (20 amp T/L CTSY fuse). It first runs up to the H/L switch and is connected at terminal 5:

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At the terminal it enters the switch and provides power to the tail lights and front parking lights whenever the H/L knob is pulled out. The 9 BRN circuit starts at terminal 4 on the H/L switch:

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So you have two possible general areas where the problem might exist: the front lighting part of 9 BRN and the rear part.

You disconnected the rear wiring harness as a test and the fuse still blew. In a way that's good - you eliminated all the wiring associated with the rear tail lights, side markers and license plate lights. The only place there could be a short/ground would be in the single lead that runs from the firewall transit to the rear lighting harness plug:

You must be registered for see images attach

Unless your exhaust has been modified or work has been done on the frame recently, it's probably a good bet that the problem is not on that single lead from the FW to the plug. I would move on to the front lighting.

There are 6 light assemblies in the front end that are served by the 9 BRN wiring. The two combination parking/directional lights, two dedicated parking lights and two marker lights:

You must be registered for see images attach

You should check each of them - and all the interconnected wiring. It might be easiest to unplug every light assembly that has a 9 BRN lead connected to it. Then, with them all unplugged start reconnecting them one by one. If the fuse blows when a particular light is plugged back in check the socket for shorts.

Thank you for all of this.

When you say to "unplug every light assembly" will removing the bulb be sufficient for this? I have every light bulb out of every light on 9 BRN and the fuse popped. I will double check the schematic and make sure I didn't miss any of them.

The single 9 BRN rear lead may be the culprit as I have done both exhaust modification and had the bed lifted up to service a gas tank. I traced the wiring harness (still in the factory loom) from the cab area all the way back, doesn't look like there is anywhere it could have gotten damaged, but I will look again.

 

[johnnydefacto]

fyi it is a dually so I have the 5 roof lights that I think are serviced by the front 9 BRN and the rear fender lights that I think are serviced by the rear. I have all the light bulbs out.

 

[johnnydefacto]

okay I pulled all the running light bulbs. I disconnected the rear taillight harness.
I traced the brown wire from the rear harness all the way up to the firewall. it all looked good (at least the 60% of it that I could see), but I went ahead and cut it right at the firewall as it exits out of the black plastic box/connector/ thing with a bunch of other wires.

The breaker still popped. I think that after where I cut the brown wire it splits to the front and back right? or does it split before it exits into the engine compartment? So what I am asking is where I cut it at, did I only take the rear lights out of the circuit or did i get both the rear and front lights?

So its either the HL switch, possibly the front running lights somewhere, or the wire from the HL switch before it goes into the firewall/engine compartment. I have followed that brown wire out of the HL switch under the dash, it goes straight up and disappears (i need to pull the dash and gauge cluster to try to trace it. But from what I see it looks good.

And the drk green wire going to the 5amp fuse should only get power when I pull the HL switch correct?

 

[chengny]

The roof markers are not specifically associated with the R05 (dually/wide side) package. They were an available option on fleetside bodies as well. Those 5 roof markers are switched through the same contacts in the H/L switch as the front and rear markers. They connect to the H/L switch at terminal 3 which is normally not used. Terminal 3 is internally jumpered to terminal 5 (the terminal to the T/L & front parking lights):

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The hot lead to the roof markers is black. It is the only black lead to the H/L switch. You could release it from the harness connector. Then, with markers no longer in the circuit, you could plug the connector back onto the switch and see if the fuse blows. If not, the markers are the problem.

The R05 option includes 9 rear marker lights in addition to the standard two. A front & rear fender clearance lamp (on each side) and the five tail gate markers:

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Thing is; those extra lights that are required with the R05 set-up are all included in the rear lighting harness. Previously you isolated that group and turned the headlights on. The fuse didn't blow. So, along with the normal markers, tail lights and license plate lighting, you have effectively eliminated all those extra lights.


Since you have done some work in the area behind the cab (the exhaust work, bed removal & gas tank repair), it might be best to ring out the brown lead that goes from the bulkhead connector to the rear harness plug connection.

Release the bolt that secures the plug to the bulkhead connector in the engine compartment. Pull the plug away from the bulkhead connector and locate the terminal for the brown lead to the rear lighting. The female half of the connector (on the firewall) will look something like this:

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And the male half - that you pulled from the connector - will look kind of like this:

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Your male plug will look different. It will be made up of 3 sections. One of the sections (the smallest one) will only have 4 wires passing through it. The wires will be colored like this:

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The block they pass through won't be in that position however. The block for your rear lighting leads will be in the lower right hand corner when looking at the firewall:

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Locate the brown lead and use your meter to check for continuity to ground. If you get a beep - or a reading of 0 ohms - the short circuit is in the run between the block and the rear harness plug.

 

[johnnydefacto]

Here I removed these two small connectors from the bulkhead connector. It looks like front brown running light wire is in one harness and rear brown is in another. I pulled my h/l switch and the fuse still popped. So now my bad wire is somewhere between the h/l switch and the bulkhead connector OR could it still be that black roof marker lights wire that is on the h/l switch right next to the brown running light wire?

Also I have a second brown wire sharing the same connector in the h/l switch. It runs up into the driver door area and quickly joins a orange wire (with a brown stripe I think)

 

[johnnydefacto]

The roof markers are not specifically associated with the R05 (dually/wide side) package. They were an available option on fleetside bodies as well. Those 5 roof markers are switched through the same contacts in the H/L switch as the front and rear markers. They connect to the H/L switch at terminal 3 which is normally not used. Terminal 3 is internally jumpered to terminal 5 (the terminal to the T/L & front parking lights):

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The hot lead to the roof markers is black. It is the only black lead to the H/L switch. You could release it from the harness connector. Then, with markers no longer in the circuit, you could plug the connector back onto the switch and see if the fuse blows. If not, the markers are the problem.

The R05 option includes 9 rear marker lights in addition to the standard two. A front & rear fender clearance lamp (on each side) and the five tail gate markers:

You must be registered for see images attach

Thing is; those extra lights that are required with the R05 set-up are all included in the rear lighting harness. Previously you isolated that group and turned the headlights on. The fuse didn't blow. So, along with the normal markers, tail lights and license plate lighting, you have effectively eliminated all those extra lights.


Since you have done some work in the area behind the cab (the exhaust work, bed removal & gas tank repair), it might be best to ring out the brown lead that goes from the bulkhead connector to the rear harness plug connection.

Release the bolt that secures the plug to the bulkhead connector in the engine compartment. Pull the plug away from the bulkhead connector and locate the terminal for the brown lead to the rear lighting. The female half of the connector (on the firewall) will look something like this:

You must be registered for see images attach

And the male half - that you pulled from the connector - will look kind of like this:

You must be registered for see images attach

Your male plug will look different. It will be made up of 3 sections. One of the sections (the smallest one) will only have 4 wires passing through it. The wires will be colored like this:

You must be registered for see images attach

The block they pass through won't be in that position however. The block for your rear lighting leads will be in the lower right hand corner when looking at the firewall:

You must be registered for see images attach

Locate the brown lead and use your meter to check for continuity to ground. If you get a beep - or a reading of 0 ohms - the short circuit is in the run between the block and the rear harness plug.

I PM'd you but you can disregard. So I found the culprit. The terminal 3 on the H/L switch has 2 wires coming out of it. 2 brown wires. One is supposed to be the black one to the top marker lights, but previous owner cut and spliced it, so 6" up it turns black. This one is not the culprit as I disconnected that splice and still popped my fuse. The culprit is the brown wire (with orange stripe) that comes out of terminal 3, goes up behind the dash towards the driver door, it quickly meets up with an orange wire that comes out of the fuse box, on the top left, little black plug connector.

I do not know what this goes to. I now have running lights, dome lights, cargo lights.

I will go back and look at the schematics, but I am electrically lame so if someone knows what it is, I would appreciate it. Thank you.

 

[johnnydefacto]

here it is. If looking at the fuse box from driver seat, it is the 2nd row from the top, 2nd one in from the left. It is marked as "c" on the picture.

So it is orange and it goes up and meets up with the brown/orange wire coming from terminal 3 on the H/L switch. they are connected together like a set of speaker wires would be. The brown/orange wire is hot when you pull the h/l switch, but I do not know if the orange "c" wire is hot or not, or when.

 

[johnnydefacto]

Found it!!!

So the previous owner tied a brown wire into the terminal 3 spot for the top marker lights, along with a constant hot wire into the fuse block slot "C". He used this for his aftermarket radio. I pulled his radio and installed a new one and only used the constant hot, and what i thought was with it, a ground. I ran all new speaker wires and amps so I ditched all the other wires. Well I thought I hooked up the factory stereo ground to my head unit, but what I did was hook up the running light roof markers to my radio ground, so as soon as i pulled my H/L switch out, POP. Problem is my stereo has been working perfectly, so i did not think that was the culprit. I must be getting a ground from the metal dash when I mounted my head unit, because it is still working great.

Anyhow, thank you for the schematics. I now know a lot more about my truck because of my F-up. You guys are great.