Hi I posted awhile back about my turn signal fuse blowing when I turn the key on. Since then I have replaced the signal switch and the ignition switch. and now I have discovered that if I leave one battery disconnected it won't blow the fuse but the second I hook up the second battery it blows it. Any help is always appreciated Thanks.

 

That's weird. .. try pulling bulbs out and hook up both batts ..

Then reinstall one at a time checking function for each elec leg ..

Make sure bulbs are correct and sum of amp draw doesn't exceed the fuse rating ..

 

Thank You Leroy I will try it. I also checked the fuses one at a time by pulling one and then putting the fuse in the turn signal slot and turned on the key and it blew every time on all of the fuse's.

 

yep fixing dang blinkers and brake lights that don't work is no fun ..

it's always best to hunt down the problem ..

but whenever possible i just leave whats working alone and run new wiring then splice it into where it's needed ..

for something like this .. a few junkyard blinker delay boxes a few extra fuses .. a lead in from the turn signal switch .. hot in run .. wiring to the blinker bulbs .. but only after easier methods are exhausted ..

i've done alot of collision work .. and some things just never work right once hit at 50 mph and cut apart between 2 vehicles .. often i have had to run 'custom' wiring

 

which battery causes the problem, and is there anything else hooked up to it?
there is a definite short in that battery wiring if it blows the fuse every time that battery is hooked up.

 

It is the Battery the farthest from the starter and there is nothing else wired to it.

 

Upon my travels through this wiring issue I came across a bare wire on the positive lead coming from the ALT somebody had stripped the casing from it down in the plastic conduit where it could not be seen and wrapped it with duct tape. The previous owner had used a shop down in az that was known to do this and screw up alternators. but this did not resolve my issue.

 

Im thinking the ground side of that battery could be part of it. For example what if the short is to a part of the body/frame/engine/ that is only well grounded to that battery. Does anything stop working when you only have one battery hooked up? That would give some clues.

 

I posted a follow-up reply to your other (same issue) topic about 6 hours ago : https://www.ford-trucks.com/forums/1...l#post16252758

Basically saying I would post information in THIS thread rather than the other one.

If I seemed cranky it was because I've been very tired, in some pain (and a bad insomnia night too).

Originally I assumed that there is a short in the wiring of one of your 4 turn signal circuits, between the fuse panel and the turn lights. (RF, LF, RR, or LR) I had planned to post some simple advice and test procedure to find out which one has the short - testing the downstream side of the wires in the turn signal switch CONNECTOR on the steering column. I have that about half finished with the switch connector diagram, which terminals to connect with the test light for each circuit, wire colors and where each of those wires go, plus part of the wiring schematic. (those can be complicated with lots of cross references to other pages with more info, schematics, diagrams etc. to find out what other components might be spliced into the circuit, (Just the turn signal flasher and hazard lights flasher in this case), and where the connectors, splices and ground points are located.

Same for the Ignition Switch wiring but I don't think that is going to be the problem since it only gose from the connector to the fuse panel

I know what I'm looking at and how to trace the circuits but I've never done much of this automotive electric troubleshooting before so it's new to me and going slow. The manuals on CD that I have are very difficult to navigate through and find things quickly (and also to extract the information from) but I want to make sure that what I present is correct so I need to verify that in the schematics which is like learning the wiring of the truck while I go.

I got side tracked looking at a lot of schematics including trailer harness wiring to figure out if disconnecting the power to the trailer harness would help to locate the problem or not help at all. I haven't determined that yet but the trailer harness should have a tag on it under the hood and that harness (with label) should be on the driver's side between the engine and outer fender (too tired to go outside and look now) but I think it goes down by the headlight and then comes back up on the passenger side behind the battery and has two wires that connect to the relay on the fender well. The Yellow wire is to the exterior lamps on the trailer and the Red wire is power to the trailer. Initially we'll be testing with the batteries disconnected so I guess we can leave those disconnected for now.

Sorry I'm so slow in helping to figure this out but for me it's a learning experience which is why I am doing it and also why I am slow.

THEN I noticed the turn signal flasher in the circuit and wondered if a flasher can short out and cause a fuse to blow- I've never encountered that scenario before and forgot (or too tired to remember) what exactly is inside of the flashers to know if they can short out like that. It's a thermal switch as I recall or sometimes a relay.

You can easily remove and test the turn signal flasher - it's in the front of the fuse panel - at least you'll know if it's good - scroll down on the page at this URL and you'll see how to test it I didn't read through this because I am too tired : Testing and replacing a flasher unit | How a Car Works

If you happen to be looking at any schematics or diagrams before I post some images, here the wire color abbreviations that FORD Motor Company uses:

WIRE COLOR ABBREVIATIONS

BL = Blue ...............................N = Natural
BK = Black .............................O = Orange
BR = Brown ............................PK = Pink
DB = Dark Blue .......................P = Purple
DG = Dark Green ....................R = Red
GR = Green .............................T = Tan
GY = Gray ...............................W = White
LB = Light Blue .........................Y = Yellow
LG = Light Green

Ground is always Black unless it's a component that someone else put in and didn't follow the FORD rule.

[NOTE: REAR TURN AND STOP LAMPS ON THE FLARESIDE PICK-UPS ARE GROUNDED AT THE SOCKET. So, a corroded socket can result in a bad ground.])

Many wires will have one base color with a thin stripe (also called a "tracer) of another color. For example, a Dark Green wire with a Yellow stripe (or tracer) will be represented as DG/Y on a schematic or diagram.

It's 5:35 AM right now and I am way too tired and burnt out to write anything more or I would post the images I have and explain the testing procedure I had in mind. So I'll be back during "coffee and pain pill hour" after I wake up." Probably around noon or 1-2 PM.

I am about brain dead right now and don't know if I should even post this but I will

 

The batteries didn't happen to accidently get wired in series (24V) vs parallel (12V) did they?

 

I have tested the flasher and it is good and the wiring for the battery's is fine I pulled the hot and grounds and took them out of the plastic conduit and they are all in good shape. the leads all look to be original equipment.

 

I would measure the system voltage at some convenient place, like between chassis ground or the engine block, and the starter solenoid on the fender. First with one battery , then with two. I suspect the voltage will be 12V, and then 24V
If the batteries are wired in correctly in parallel , the only difference to the circuit is more storage capacity. The voltage and max current ( for the purposes of your blowing fuse ) are the same. Adding the second battery should not cause any additional fault.
Since it is causing a fault, I suspect the batteries are not wired in parallel.

Only other thing I can think of is that in the process of hooking up the second battery, you jostle the wiring harness and cause a short.

Good luck.

 

Hi I have narrowed my short down to these 2 wires they go into the harness on the passenger side and down past the box for the heater. The 1 comes from the positive post on the Alt and the other comes from the Voltage reg. When I plug them in on the connector the Park lights come on.The ones that I'm chasing are the Yellow and the Black with Orange stripe after the fuseable links on the Female side of the connector pictured. Any Idea where they run to? Thanks

 

Also both sides of the female connector are hot with batterys hooked up the small green wire runs to the passenger side headlamp just wondering are both sides supposed to be hot???

 

Sorry I didn't get back to your topic last time- the reason is that I got sick and didn't have the energy to focus on it - PITA without the correct schematics for an 85.

I'm just going to have to go with the 87 schematics that I have to help. Most of it should be the same

I did trace the circuits last night for all of your wires in question with regard to the parking lights. It could be a bad headlight switch. I'll see if I can find the procedure for testing the headlight switch after we chase the wires. (I saved the work I did before on your turn signal problem so we can pick up on that too).

Let me pull up the schematics again and I have to convert the images to another format (doing that now) if I need to post them. That will take a few minutes... be back shortly