1989 Ranger I did a ton of work and I'm about to give up "need help"

[JayDeavor]

I am at my breaking point, I have a 1989 Ford Ranger 4x4 with a 2.9L engine that probably should have been in its grave yard but I have a soft heart for the first generation Rangers. I practically rebuilt this whole truck from front to back. The truck was pretty beat up from a young kid that had it before me. It was okay though because I had an 1989 Ranger myself that was getting way to rusty for the road, but I had a ton of new parts that I swapped over.

I didn't like the color of the newer to me trucks interior so I swapped everything including the complete dash itself. I even went as far as changing all the wiring except the harness that operates the rear lights and the interior harness that operates the door jam switch, rear speakers, dome light and cargo light. All other wiring was swapped over from my daily driver. Basically everything was swapped from my daily driver to the newer truck even the windows.

The complete surgery went very well until it was time to fire the truck and I didn't have any power to the fuel pump. After making sure the relay was good I remembered I forgot to hook up the ground wire from the relay. Since the ground wire for the relay was broken off of the ground wire, I ran a new wire from the relay to the core support right by the battery with the other grounds and everything seemed to go good until I noticed the fuse blew for the Parking Lights, License Lights, Engine Compartment Lamp, Lamps on Warning. When replacing the fuse with a new on it popped again right away so now I know I have a short to ground somewhere..

This is where I am about to give up. I started in the rear unplugging lights working my way to the front. I just can't figure out where my short to ground is. I put an old license plate socket and bulb into the fuse spot to try and find this short to ground no matter what I did the light just wouldn't go out. I went as far as pulling the complete dash out of the truck and checking the wiring the runs from behind the fuse box. The fuse #10 that has the short has a light brown with black tracer and a thicker dark brown wire. The light brown with black tracer goes up to the headlight switch and the dark brown wire goes to fuse #11 (Speed Control Amplifier & Radio, All Wheel Drive) (Now the Radio has not been installed in the newer truck yet)

After checking everything I could think of, I threw the complete dash up on the engine bay and hook up the main harness just so I could have and easier time than installing the dash back into the truck. I stilled had a hard short to ground so I just started unhooking everything that had a plug. All plugs on the back on the dash pad, All plugs in the engine bay on the driver side and also unplugged. I noticed when I remove the ground wire on the fender well right by the cruse box the light goes a little dim but doesn't go out same goes for the ground on the drivers side that is connected to the core support. The light goes dim but doesn't go out. I tried the headlight switch from both trucks and it is still the same thing, nothing changes.

I am pretty much at the end of my ropes. The only thing that I can see that is still hooked up to the main harness is the wiring that runs from the main harness across the front of the truck over to the power distribution box. ( Yes everything at and around the PCM is disconnected ). When I pull the 40 amp fuse for the headlight out of the power distribution box, my test light goes out. I did not open the harness that runs from the main firewall across the front to the power distribution box.

Am I even going about finding this short to ground the right way? Should I open the harness that runs to the power distribution box and look around in there? I am needing help to get this part figured out so I can get this mess looking like a good truck again.

Thanks in advance to everyone

Jay

in the picture you can see the dash is on the engine bay and in the red circle you can see my short to ground testing light is still on even though everything is unplugged

 

[ericbphoto]

Wow! That's quite a story. You're definitely not troubleshooting it the way I would. But that doesn't matter. You are where you are. So, we need to find the problem.

The last thing you did before the problem appeared seems to be replacing a broken ground wire. I would start there and make sure that new wire isn't touching something that it shouldn't be touching. And, are you SURE it was a ground wire to begin with?

Usually when a problem like this pops up, it has something to do with the last thing you messed with.

 

[ericbphoto]

I would like to make a recommendation, if you don't mind. I sense that you are very frustrated with this. But, as you unplugged so much stuff and removed the dash, etc. You have made it more difficult to troubleshoot and greatly increased your opportunities to introduce more problems later when you put it back together. I would encourage you to put everything back together now and try to get back to square #1 with everything in it's original state.

In troubleshooting, it is often useful to "divide and conquer" in an organized way. Your truck has 2 fuse panels. One in the engine bay and one in the cab. The panel in the cab is fed from a fuse in the engine bay fuse panel. When removing that fuse, if the problem persists, then you know the problem is in a circuit that originates in the engine bay. At that point, you have eliminated all those irritating circuits in the cab panel and you don't have to mess with them. Then, you can concentrate on the few circuits in the engine bay panel. The opposite is also true. So, that one fuse helps you divide the whole electrical system into two parts so you can conquer the part with the problem and not be sidetracked by all the others. Let's start there.

 

[JayDeavor]

ericbphoto
Yes I am pretty sure it was a ground. The ground wire comes from the engine block and attaches to the frame inside of the passenger wheel well with a 10mm bolt. from there it continues up to the battery. There is a small wire that come from where it attaches to the frame up to where the power distribution box and it has a round plug. The wire that goes into the harness right by the power distribution box has the mating round plug. I assume it goes to the fuel pump relay. the small ground wire was totally shot so I just cut it off from the main ground wire and spliced a new wire from the harness to the core support. Before I cut and spliced those wire together I did NOT have any power to my fuel pump. After connecting those wires I had power to my fuel pump. I did trace that wire before I spliced them together to make sure it did go to the fuel pump relay and it did.

 

[JayDeavor]

Eric;
I will install everything back to original tomorrow. If I am understanding, The fuse panel under the dash gets its power from the power distribution box under the hood. Since I have unplugged everything that had a plug and I still have the short to ground I am guessing that my problem is lying between the main harness connection the goes into the fire wall and the power distribution box.

There are 3 body grounds that I can think of off the top of my head under the hood. 1st location connects to the fender well right behind the cruse control actuator and has 2 wires grounding. 2nd location is attached to the core support behind the right (drivers) side headlight with one wire attached. 3rd ground location is right behind the battery. the 3rd location did have 2 wires grounded but now has 3 wire because of grounding the fuel relay.

When I remove the ground wires in location 1 and 2, My testing light in the fuse panel gets dim. When I remove the 40amp fuse from the power distribution box for the headlights, My testing light goes out.

So my question is, since my testing light gets dim when removing ground wires located in position 1 and 2 and the testing light goes completely out when removing the 40 amp fuse, wouldn't my problem be between the main connection at the fire wall and the power distribution box?

 

[ericbphoto]

The distribution box in the engine bay gets it's power from the battery. It does not go through the firewall.

 

[JayDeavor]

Eric;
Yes, If I am correct the power comes from the battery and goes to the power distribution box. From there power runs through the harness that goes a long the front of the engine bay and back to the big round connector under the brake booster through the fire wall and connects power to the fuse box under the dash. I am wondering if my problem could be in this area because of the light getting dim when removing the body ground from the fender and core support. I'm not sure. I am going to put everything back together like you suggested tomorrow and hope we can get this figured out.

 

[JayDeavor]

well I installed everything back to the way it is supposed to be and I also checked the wiring harness that runs from the power distribution box to the main connection into the cab and everything looks okay except the back of the turn signal socket. doesn't appear to beany wires touching but they are starting to look a little crusty and greenish. I am still showing a short to ground somewhere. I am at a loss at this point!

 

[ericbphoto]

Ok. So, let's focus on the circuit that you Said blew a fuse. If that us all one circuit on your truck, then that is where the problem should be.

I noticed the fuse blew for the Parking Lights, License Lights, Engine Compartment Lamp, Lamps on Warning.

My truck is newer and my circuits are laud out a little bit differently. I think we have your wiring diagrams in the tech library. I'll go look and see.

 

[ericbphoto]

So, is it fuse 10 in the cab fuse panel that blows?

 

[ericbphoto]

Diagram here shows that fuse 10 in the cab fuse panel supplies exterior lights, the gauge panel lights and backlighting for the stereo that you said has not been installed yet.

If the light switch is turned completely off, there should be no current flowing in that circuit. The wiring from fuse 10 to the light switch, radio and gauge panel lights is all in the cab. The only part that goes outside is for the exterior light circuit. If you pull the fuse for the gauge panel lights (instrument panel) and fuse 10 still blows, then the gauge panel is not the problem. Make sure the wire for the radio backlight is taped up and not touching ground.

 

[ericbphoto]

Meanwhile....

Hey @RonD . Could you please join in on this?

 

[RonD]

First thing from original post is the fuel pump relay, its has no full time ground wire, the computer grounds it to turn it on and off
So I would disconnect that "new" ground wire, NOW!!!!

Second was Jay mentioned a brown/black wire..................to Main light switch??

As said above if main light switch is OFF and fuse 10 blows, then the problem is NOT in the wiring for the lights, for sure
The main light switch has power all the time, key on or off doesn't matter

Unplug the main light switch and try a new fuse, if it doesn't blow replace the light switch, its a common failing on older vehicles
If it does blow then it would probably be easier to run a new wire from switch to fuse, than unwrapping the harness

 

[JayDeavor]

wow. I am going to try everything that is mentioned here today. I actually got the circuit breaker fuses in the mail yesterday so I don't keep spending money on fuses. I will report back here in a little while and give you an update on what I came up with and what I did.

Thank you guys for helping. I actually closed the garage door yesterday thinking I am never going to get this truck finished because I don't want to complete the build until I get this figured out.

 

[ericbphoto]

wow. I am going to try everything that is mentioned here today. I actually got the circuit breaker fuses in the mail yesterday so I don't keep spending money on fuses. I will report back here in a little while and give you an update on what I came up with and what I did.

Thank you guys for helping. I actually closed the garage door yesterday thinking I am never going to get this truck finished because I don't want to complete the build until I get this figured out.

It's easy to get overwhelmed.