No taillights/running lights/dash lights/etc '76 Minnie Winnie

Started by ahl10492, July 01, 2020, 03:57 PM

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ahl10492

Alright guys so picked up my MH (1976 MW25C) and noticed on the way home that there were no instrument lights. Annoying but not horrible, until I realized the taillights were out as well. The 15A fuse blows as soon as the headlight switch is on (although the headlights work). Any suggestions on where to start?

Rickf1985

What 15 amp fuse is blowing? The headlight switch has it's own circuit breaker so the fuse is covering something else in the wiring. Check to see if there is a trailer harness and if there is then the best bet is to cut it all off since it is probably butchered to begin with and needs to be redone. Eliminating this  will go a long ways to getting rid of potential shorts. If this vehicle sat for a long time and there is any evidence at all of mice in it then you need to climb under the dash and look closely at the wiring because mice LOVE to chew the wiring and use it for nests. Many a rig has burned to the ground because of this.

ahl10492

Hey Rick, thanks for the response. Havenââ,¬â,,¢t seen any evidence of critters under the dash thankfully but not ruling it out. Will also need to look for a trailer harness.


Itââ,¬â,,¢s the second fuse on the second row in the picture (looks like itââ,¬â,,¢s labeled TAIL PARK). Just noticed the one next to it is blown as well. Having trouble finding any kind of diagram for this  i??

ahl10492


LJ-TJ

Not sure if  I can do this but I'm going to try and attach a PDF. Might work? Might Not.


Attachment removed by admin - not applicable to this vehicle

DaveVA78Chieftain


Careful about what you use for reference.  The PDF LJ-TJ linked to is for a Class A chassis, not a Class C mini.


In 1976:
1. Winnebago produced the 20RG, 23RG, and 23RD Mini Winnies (Please note there is not a 25ft version).  All of these were Class C rigs built on a Dodge van Chassis.
2. Itasca produced  the C22C, C24C, and C25C Mini. The C25C is 25ft. All of these were Class C rigs built on a Chevy P30 van Chassis (Not to be confused with the P30 Class A Chassis). For 1976 P30, you have to have:
  A. The 1974 Chevy Light Truck Service, and Overhaul (also available in our member area)
  B. The 1976 Chevy Light Truck Supplement(also available in our member area)
  C.  We do not have 74 - 76 P30 Wiring diagrams in the Member Area and I am not sure where to locate them.
Please look at the brochures I linked to and determine which model you have to make it easier for us to assist you.

Dave
[move][/move]


ahl10492

Thanks Dave! The closest resemblance on the brochures is the C25C. Did they normally rebrand these as winnebagos? From my door jam:


Manufactured: 5-76
Model: MW25CR

Rickf1985

Quote from: ahl10492 on July 01, 2020, 09:03 PM
Adding pictures
Ok, so that fuse controls the tail lights. Your problem is going to be in that section. Like I said before, the trailer harness, if it is there should come out. You can put in a new one later that plugs into the harness at the factory harness plug. Unplug that orange wire and see if the fuse still blows, it probably will but it is a starting place. If it does not you will need to find out where that wire goes. If it still blows I would go under the rear end and do a good look around the wiring there first and if you don't see anything start following it forward looking for any bare spots or burnt or chewed wires. Also take the light covers off and look in there for anything that looks out of place. Take the bulbs out and try the fuse again. I hate to say it but you may go through quite a few fuses until you find this, whatever you do don't be tempted to go to a bigger fuse! You may find it but by then you will be looking at a LOT of burned wires!

ahl10492

No luck on removing the orange wire or removing the taillights. Still blows the fuse.


Popped the covers off all of the running lights as well and donââ,¬â,,¢t see anything thatââ,¬â,,¢s obviously wrong with any of them.


Does anyone know where the wiring goes after it leaves the switch?

Rickf1985

The headlight wires go directly to the headlights, the tail light wires and brake light wires go to the fuse box and then the tail light wires go back to the tail lights and the front running lights and the brake lights go through the turn signal circuit. Unless you are very familiar with automotive wiring this will be pretty hard to follow without a diagram. Automotive electrical was one of my specialties along with carburetors when I had my shop but I always preferred to have the diagram if at all possible. Tracing wires without it can take hours and possibly days. And you will need several Looong jumper wires. That fuse may cover the front parking lights also, do they work or not? Directly opposite that fuse box on the outside of the firewall will be a large plug with a bolt in the center of it. This is the main harness connection to the fuses. You can take that bolt out and remove the plug and see if there are any burnt connections in there. Usually this is what you do when thing do not come on and you will find corrosion on the connections but anything is possible. Another thing you can try is go to the back and locate the rear light harness and work forward until you find a plug. There should be one somewhere in the back no further forward than the rear axle. If you find it then unplug it and try again. If you fuse still blows you know the problem is forward of that but leave it unplugged and work your way forward along the harness. Same thing with the dash plug although once unplugged you may not have any power at all, some vehicles get their power from the engine side of the plug. It is NOT the switch, the fuse is after the switch so only concentrate on what that fuse covers. I will see if I still have any of my old manuals that may cover it.

Rickf1985


Rickf1985

Here is one you need to download but for some odd reason it does not have the wiring. I am going to look for a 76 Chevy van and that should be pretty close to the same thing.


https://www.gmcmi.com/wp-content/uploads/2014/05/P30-Chassis-Manual.pdf

Rickf1985


ahl10492

Awesome thank you! I actually took your suggestion and managed to find the plug for the taillight harness through the frame (although it was strangely very far up - near the transmission)


Once I unplugged the harness I stopped blowing the fuse, so I guess now itââ,¬â,,¢s just a matter of figuring out where the short is from the plug back..


Any suggestions? A friend suggested I put in an automatic circuit breaker and flip the switch to look for smoking wires under the chassis, then cut and splice in new wire. Would rather not go that route haha

Rickf1985

Here is one more.
http://www.73-87chevytrucks.com/techinfo/7387CKMans//Wiring/ST_352_76_1976_GM_Light_Truck_Wiring_CK_10_30_Only.pdf


Like I said, most of the time I found the problem in a bad trailer harness. If it is there cut the entire thing out. Then take out all of the bulb from every socket. Now go under there with an ohm meter and ground the black lead to a good clean ground (yea right, clean metal on a 44 year old Chevy! LOL.) Then with the red lead probe the connectors one by one and where ever you get a full reading you have a short. Go to one of the diagrams I sent and see what wire that is and that will make it a lot easier to track down.

ahl10492

Ooooof youââ,¬â,,¢re right I think finding a ground might be the hardest part of this LOL


Sorry for such a basic question but Iââ,¬â,,¢m a serious beginner when it comes to electrical testing...


I should:


Set it to 20v (DCV 20 on my multimeter)
Ground the black
Use the red to probe the pins on the connector from the harness back (I.e. towards the taillights and not the engine side)
And look for something but not sure what  Hm?

ahl10492

This is my multimeter for what itââ,¬â,,¢s worth

Rickf1985

That will work, as long as the batteries are decent in it. Click the knob one notch to the left where it says 2000K. That is the Ohms scale you will be using. There should be something like 0.L in the display, now touch the leads together and the display should read all 000. If you see anything but 0.L in that window then you probably have a short. In reality you could have a resistance from a bulb still left in but lets not go there right now since you are not that familiar with this. Start with that, I have to get my dogs and wife fed and I will check back in a little while. If it reads all 000 then you found your short unless you are on a ground wire and the only place there will be a ground wire is the trailer harness I said to cut out.

ahl10492

Youââ,¬â,,¢re the man Rick


I cut out the trailer harness and the shoddy splices they used to tap into the light harness  D:oH!


I found the wire that has a bad ground by connecting them one at a time and flipping the switch momentarily (watching the fuse start to bend but killing the power before it popped). It looks like it was the power wire thatââ,¬â,,¢s running to the side marker, but not sure until I pull it out.


Now itââ,¬â,,¢s just a matter of figuring out which wire is which and reconnecting them. I donââ,¬â,,¢t seem to get any power at the lights now so thatââ,¬â,,¢s another problem.


Alas Iââ,¬â,,¢m heading to Pennsylvania for the weekend, so will report back on Sunday when I dig into her again.


Enjoy your Independence Day!!!

Rickf1985

You do the same, at least you are going with progress made.

Oz

Awesome, Rick!


You'll find that problem and fix it.  Keep going!
1969 D22, 2 x 1974 D24 Indians, 1977 27' Itasca

ahl10492

UPDATE


Hope everyone had a great Fourth of July!!


I got under day and reconnected the four wires from the harness to the taillights (without reconnecting the rooftop running lamps)


I havenââ,¬â,,¢t blown a fuse and it looks like I have both taillights and brake lights!! I put them on with spade connectors just in case I wired them up wrong (the PO cut out the original harness for some reason so the colored wires wouldnââ,¬â,,¢t match a diagram even if I had one). Iââ,¬â,,¢m going to wait until itââ,¬â,,¢s dark and do a walkaround, but I think Iââ,¬â,,¢m okay for now!


The only thing I donââ,¬â,,¢t have is reverse lights, but then again since there are only 2 power and ground coming from the harness (brake and tail?) Iââ,¬â,,¢m not sure which they would even be. Maybe someone with better knowledge can chime in

DaveVA78Chieftain

QuoteThanks Dave! The closest resemblance on the brochures is the C25C. Did they normally rebrand these as winnebagos?
From my door jam:
[Manufactured: 5-76
Model: MW25CR

While I could not locate a Winnebago Brochure for MW25CR, I did locate a Parts Books for:

MW25C

MW25CD

1976 MH Common Items

Dave
[move][/move]


ahl10492

Quote from: DaveVA78Chieftain on July 06, 2020, 06:08 PM
While I could not locate a Winnebago Brochure for MW25CR, I did locate a Parts Books for:

MW25C

MW25CD

1976 MH Common Items

Dave


This is perfect, looks like the same layout. Thanks Dave!

ahl10492

I now have brakes, rails, and running lights! Thank you to everyone who helped out and shared their expertise.


A couple gremlins to track down, but nothing major!


1. The rear blinkers are significantly dimmer than the hazards for some reason. This is the real head scratcher? Maybe they accidentally got wired to the brake filament instead of the tail?
2. The front right turn signal doesnââ,¬â,,¢t flash (maybe a bad bulb still need to check)
3. The tail lights come on with the running lights (position 1)  instead of only with the headlights (position 2) but thatââ,¬â,,¢s just a minor annoyance
4. A couple of ground problems with some running lights but I can live without them
5. No reverse lights, but also can live without