Brake light malfunctions Need service advice

[MrMark52]

Originally Posted by Aeronaut

I have purchased the diagrams, but am not that good at reading them yet. Yes, the hazards and signals work great until I push that brake pedal, then the fuse blows. I suspect that most of the yellow wiring was factory, as it starts from connector plug that takes all colored wiring into a straight yellow and white wiring all in split loom all the way into the tail lights and there is a y that takes it back into colored wiring into the Uhaul trailer plug in. It appears there is an additional wire that was added to the electric brake thingy that was mounted under the steering column that takes a single wire all the way back to the trailering connection.
I'm glad to hear that you think that the problem might be closer to the brake pedal, as I am thinking about taking the brake, and cruise control switches out to look at them. I am 220 lbs and the geometry doesn't really allow me to get under the dash that well unless I remove the driver seat. I have done that before on a Georgie Boy class A, but wasn't a pleasant experience, especially as I don't have help easily available sometimes. I don't know if it is any easier to go through the dash on this 2004 P32 chassis. Have you any experience like that? Anyway, great to hear from you, I'll be taking a good look at the wiring around those switches to see if I can find anything.

I’m about your size and getting under out ‘02 Georgie Boy Class A isn’t easy for me either.
But at least the GB has a driver door.
Also had a ‘91 P30 chassis under 27’ Ultrastar Champion - I could get down there, but with C3 to C6 fused in my neck, and a right arm that has limited use due to nerve damage - it was darn near impossible to get under that one but I think I did one time.

If you can figure out a way to send me the necessary pages of the schematics, I’ll see what I can figure out - I don’t think the scheme’s for the ‘91 would be applicable.

A couple of things you might check -

1. Check to make sure the correct bulbs are used in the tail lights and that they are installed correctly.
2. Test the brake pedal with the tail lights removed.
3. Make sure the hazard and turn signal blinkers are the correct ones - we had issues with our ‘03 Jeep hazard flashers - when turned on, the flasher sounded like a buzzer. But the flashers and brake lights worked without issue.
There were 2 different hazard flashers built for that model, and since that Jeep came out, newer flasher modules became available that would also better handle an LED light upgrade.
The Jeep had the correct flasher in it, but I took a chance and ordered one of the newer ones - the difference being an alpha character on the suffix.

Blinkers started working - and now I have the added benefit that I can change over to LED’s if I want.
Considering the complexity of the tail/signal light circuitry, don’t rule out that your flasher might have an internal short.

4. Wiggle the wires around under dash as best you can, trying to move any wire looms away for possible grounding points.

[rlcpe]

We had similar issues on our 05 Adventurer on the W22 Chassis. The connection made between the chassis wiring and the wiring for my 7 pin was the biggest mess I had ever seen.

After much crawling and disgust, I took apart all the wires connected to the trailer plug and one by one had the wife turn on the various functions and labeled each yellow wire. I also found that they had connected one of the taillight wires incorrectly and created issues on the chassis.

Then tested the 7 pin plug and found that over time the trailer plug had gotten moist, corroded and was causing a short which acted exactly as you described. I put in a new 7 pin plug, connected to the correct wires and all is well again.

[Aeronaut]

Originally Posted by MrMark52

I’m about your size and getting under out ‘02 Georgie Boy Class A isn’t easy for me either.


But at least the GB has a driver door.
Also had a ‘91 P30 chassis under 27’ Ultrastar Champion - I could get down there, but with C3 to C6 fused in my neck, and a right arm that has limited use due to nerve damage - it was darn near impossible to get under that one but I think I did one time.

We have much in common, had spinal surgery, no fusing, but right arm not as strong any more.

If you can figure out a way to send me the necessary pages of the schematics, I’ll see what I can figure out - I don’t think the scheme’s for the ‘91 would be applicable.

I did order a schematic from WH, but have not spent much time on it yet, however I'm not an electrical engineer. If I don't have any luck with your other ideas I'll shoot it over to you for your perusal

A couple of things you might check -

1. Check to make sure the correct bulbs are used in the tail lights and that they are installed correctly.
2. Test the brake pedal with the tail lights removed.

I'm going to unplug all the lights in the back through a harness connector which is right next to the rear tire carrier in the very back, that should make test 1. and 2. pretty easy. If the fuse stays intact I'll work from there, if not I'll try 3. and look at flasher modules.

3. Make sure the hazard and turn signal blinkers are the correct ones - we had issues with our ‘03 Jeep hazard flashers - when turned on, the flasher sounded like a buzzer. But the flashers and brake lights worked without issue.
There were 2 different hazard flashers built for that model, and since that Jeep came out, newer flasher modules became available that would also better handle an LED light upgrade.
The Jeep had the correct flasher in it, but I took a chance and ordered one of the newer ones - the difference being an alpha character on the suffix.

Blinkers started working - and now I have the added benefit that I can change over to LED’s if I want.
Considering the complexity of the tail/signal light circuitry, don’t rule out that your flasher might have an internal short.

4. Wiggle the wires around under dash as best you can, trying to move any wire looms away for possible grounding points.

Definitely will do 4. I think that some of the guys with custom chassis say that they have had luck lifting the instrument panel to get access to the brake light switches easier.


Thank you much for all these ideas. Probably won't be able to work on this till Sunday evening, and will try to post results soon. I really appreciate your help

[Aeronaut]

Originally Posted by rlcpe

We had similar issues on our 05 Adventurer on the W22 Chassis. The connection made between the chassis wiring and the wiring for my 7 pin was the biggest mess I had ever seen.

After much crawling and disgust, I took apart all the wires connected to the trailer plug and one by one had the wife turn on the various functions and labeled each yellow wire. I also found that they had connected one of the taillight wires incorrectly and created issues on the chassis.

Then tested the 7 pin plug and found that over time the trailer plug had gotten moist, corroded and was causing a short which acted exactly as you described. I put in a new 7 pin plug, connected to the correct wires and all is well again.

This is interesting. I hope that that isn't the case for me as I finally cut all the wires to the trailer lights receptacle and the fuse still blew, but your problem solving has given me some things to think about. Thanks for sharing this

[Aeronaut]

Quick update. I disconnected the connector from the rear of the wiring harness to the tail lights, and unfortunately the fuse still blew. Moving forward going to try the ECT 3000. Electrical schematic from WH is horrible. I'll ask my son who is an electrical engineer if he can guide me? The instructions are virtually absent.
Of course the thought had crossed my mind that I'm just inept

[MrMark52]

Thanks for the update! But at least you have progress, and you know the issue isn’t back where the trailer harness connects in.

And yes, depending on the coach builder, lifting the dash panel is a lot easier than laying on the floor (don’t ask me how I know ��. I’ve had min off twice, the first was when I had to remount the dash board and tie into the front end cap. Story detailed elsewhere).

I would be looking around where the brake pedal arm moves around.

I have heard of situations where coach manufacturers trapped wiring between the OEM chassis and the coach build.

Just looked at the Workhorse “Body and Accessories” service manual, page 8-31. Are you loosing fuse 5 or fuse 11?
From that page above, depending on which fuse, you can find out what connector you need to locate, and further down where it’s located, to disconnect and further isolate where the problem is.
FWIW - if that what your looking at for a schematic, it’s not that hard to read. If you enter on page 8-31, the flow is downward. If your looking at the PDF on your laptop, don’t rotate the pages so the top of the page is up on your screen. You then read from from top to bottom of page as you scroll.
Wiring for the lights covers 3 pages, starting with fuses 5 and 11 and proceeding down.

How does your turn signal switch feel when you flip it? Seems I also read somewhere where the turn signal switch explodes (comes apart) internally.

[Aeronaut]

Originally Posted by MrMark52

Thanks for the update! But at least you have progress, and you know the issue isn’t back where the trailer harness connects in.

And yes, depending on the coach builder, lifting the dash panel is a lot easier than laying on the floor (don’t ask me how I know ��. I’ve had min off twice, the first was when I had to remount the dash board and tie into the front end cap. Story detailed elsewhere).

I would be looking around where the brake pedal arm moves around.

I have heard of situations where coach manufacturers trapped wiring between the OEM chassis and the coach build.

GEEZ I hope not!

Just looked at the Workhorse “Body and Accessories” service manual, page 8-31. Are you loosing fuse 5 or fuse 11?
From that page above, depending on which fuse, you can find out what connector you need to locate, and further down where it’s located, to disconnect and further isolate where the problem is.
FWIW - if that what your looking at for a schematic, it’s not that hard to read. If you enter on page 8-31, the flow is downward. If your looking at the PDF on your laptop, don’t rotate the pages so the top of the page is up on your screen. You then read from from top to bottom of page as you scroll.
Wiring for the lights covers 3 pages, starting with fuses 5 and 11 and proceeding down.

I have PM'd you about the schematic.

How does your turn signal switch feel when you flip it? Seems I also read somewhere where the turn signal switch explodes (comes apart) internally.

Turn signal seems crisp and works, however the windshield wiper on works in the two highest speeds, no intermittent modulation.
I'll keep everyone updated here in another day or so. Thanks again

[MrMark52]

I corrected my email addy to you in the PMail you.

Looking at the chassis schematic/wiring diagram for the wipers - it looks like everything goes through the wiper control - mist, off, instant wipe, delay 1 thru 5, low, and high speeds.
Speeds are dictated by in-line resistors that are all part of the switch whose output to the wiper motors is via the purple wire at the (motor).

[Aeronaut]

Originally Posted by MrMark52

I corrected my email addy to you in the PMail you.

Looking at the chassis schematic/wiring diagram for the wipers - it looks like everything goes through the wiper control - mist, off, instant wipe, delay 1 thru 5, low, and high speeds.
Speeds are dictated by in-line resistors that are all part of the switch whose output to the wiper motors is via the purple wire at the (motor).

Thank you for that. You should be getting email soon. I was wondering if there was a separate timer somewhere in the wiring. Looks like I'll be looking for a new signal switch.

[David 70]

On mine the wipers decide to not work on the intermitent setting at times. The silver control module hangs on the sterring column left side close to the floor by my foot. When it quits I give it a kick and they start working. One of these times they will probably quit completely. The controller has a number on it and I have found some on the internet so I will need to get one ordered one of these days.

[Aeronaut]

Well, I unplugged the connector to the Brake light switch and hooked up the ECT 3000. It immediately indicated that there was a short on the light blue wire outbound. I tracked it in the wiring to under the hood where I tracked it go into the engine compartment. I removed the engine cover and noticed when I moved the wiring harness there, that the instrument switched from short to open, back and forth. I shouldn't have pulled and played with it so much, as it fell to an open circuit and I could never duplicate the short again no matter what I wiggled. I plugged the connector back into the stop light switch and connected the rear harness connector. Brake lights working and the fuse is not blowing. I have no misconception that this fault will reoccur at some point. I will know exactly where to start and will track it down without wiggling those wires till I find it. I want to thank everybody for their advice and help. I could never have been motivated enough to go this far without your encouragement. I did learn how the whole dash is hinged and rotates up and away so I could look around the brake actuator and area for anything hinky. It really gives you the room you need. I have taken a couple of pictures of the dash for your perusal. Just need to remove the bottom row of screws beneath the plastic molding and a little tug and voila! I didn't know there was a whole different fuse block under there as well!
Thanks again everybody.