Hi,
I have a 2007 Ford Rangers standard cab with a 3.0 V6. The truck has 230k miles and is used for pool service in SW florida. There is rust on the frame under the bed. I will detail the symptoms of the problem I am having followed by a list of things I have done so far to remedy this issue. I really need help with this, it is summer now, business is booming and its nearly 100 degrees out.

So in the beginning I started loosing A/C fan speeds. First the lowest speed went out, then 2, then finally 3 and I was only left with the highest setting. I assumed blend door actuator. I never fixed that, because the ac still worked.
One day the fan stopped blowing completely, but in addition to that the truck would not start and not run with the ac turned on.

SYMPTOMS

• With the AC turned to the OFF position and the fan speed set to the highest speed the truck will idle fine in park or neutral.
• With the A/c off and the fan speed set to 1-3 the truck will not run.
• The truck will sputter and die in any gear if i hold my foot on the brake at a stop
• The truck will sputter and die in reverse. To back the truck up i put it in reverse for a few seconds and then pop it in neutral, repeating this until im backed out of where i need to go.
• If the lights are on its nearly impossible to reverse. The sputtering is much more pronounced and excessive with the lights on
• While driving, if i put the blinker on it blinks at normal speed. When i press the brake the blinker blinks very fast as if the bulb is bad. Foot off brake and blinker goes back to normal speed
• The taillights/blinker appear to be very dim and hard to see from the car behind me
• Under the hood 2 red wires coming from the alternator had gotten smushed by the upper radiator hose and the insulation rubbed off until they were sparking. I wrapped them up and tied the hose out of the way
• The trailer harness was mangled as if PO cut if off sloppily and left it like that

Here is a list of everything I have tried so far in an effort to fix this issue. Nothing has worked or changed this in any way and every symptom listed above still persists (besides sparking wires)

TROUBLESHOOTING​​​​​​

• New blower motor
• New blower resistor
• Cleaning G105 and G103 ground locations (cant find G205)
• Inspecting the wiring harness under the hood and under the vehicle
• Went to junkyard to get new GEM module. Apparently they stopped putting those in Rangers after 2004
• Checked all fuses and they're all good. Not sure about the relays
• Cut off the mangled edge of the trailer harness and wrapped each individual wire in electrical tape and then wrapped it up nicely to prevent further damage

At this point I am at a loss. I am going to get a power probe to further investigate but I've only ever used one once and i'm not totally confident in my ability to effectively use it to solve this issue. Maybe it will be more apparent once I have it in my hand and begin testing with it. If anyone here has any recommendations or experience with a similar issue your input is greatly appreciated. I am struggling right now with this truck and I really don't want to have to get another truck and have a payment. I need this truck to last me at least 1 more year while I try to get my business off the ground. Thanks ahead of time for any advice

 

Pull the plugs that are at the fuse box on the passenger side kick panel. They're known for getting corrosion in them and causing all sorts of strange issues. Also, if there's a connector below the driver's seat, you'll want to disconnect that and make sure there's no water or corrosion in it.

 

Reads like you have a problem in the SJB(smart junction box), SJB replaced the GEM starting in 2004 Rangers

SJB is inside the passenger side kick panel, Fuse box is part of the SJB

Pictures here of SJB: https://www.therangerstation.com/tec...-modification/

These were/are notorious for water intrusion and corroded connections, picture here: https://i1.wp.com/sparkys-answers.co...0/DSC09929.jpg

That's one of the larger connectors

ALL of your symptoms can be explained by SJB issue

So your first instinct to check the GEM was correct, its just called the SJB in a 2007 Ranger, the BCM, body control module

 

Which connector is under the drivers seat? There’s apparently a ground (G205) somewhere in the left front floor of the truck that I can’t find anywhere. The other grounds look good, but the floor is kinda beat up and the carpet/plastic flooring got holes in it and dirt underneath it. I guess I might need to vacuum out underneath there. There is a connector that appears to go from the drivers seat into the floor underneath it. The seat is not electrical so not sure what this connector is for yet.

Thank you! I will have to check that SJB I read something about that after the GEM failed attempt but I wasn’t sure where it was so those pictures you provided are very helpful.

 

So I pulled the SJB and there was clear signs of water but not bad. It’s definitely gotten wet but the chip looks fine and the connectors had like 1-2 pins on each that had some blue corrosion. I’m not sure this is what’s causing my problem. I will clean everything up and install it and see if that fixes it. Where else can I start looking?

 

The corrosion IS the issue, no reason to look farther

 

Yep, you'd be surprised how much a little corrosion like what you have can do.

 

Alright we will swap this out and see if it fixes it. I read a thread where one guy had some electrical issues and saw similar corrosion in there. Not a whole lot. He changed it out and it didn’t fix the issue. His problem was a blinker as well. So I was worried that it wouldn’t fix it if I replaced this but I’ll see if I can obtain one that’s not corroded

 

Yes, unless you want to do some board level diagnostics, it may not be the problem

You can test voltages on the wiring at the SJB, that's what corrosion effects, voltages
But not sure if Ford ever published a diagnostic for Ford Shop techs in regards to SJBs, they just suggest replacing it if there is a problem

You can get Fords Electrical troubleshooting manual they send out to Ford Shops every year for every model they sell
Yours would be called "2007 Ranger Wiring Diagrams"
Its one book of the 3 or 4 books in the 2007 Ford Ranger "Shop Manual" set, but its often sold on its own

One here on ebay: https://www.ebay.com/itm/2007-Ford-R...-/350006945132

People buy and sell these all the time, so they are basically free because you can resell it when you don't need it any more
This would be specific to 2007 Ranger and include all sub-model wiring, i.e. engine and options

Diagnostics is not usually as straight forward as most would like, lol
Even a Flat Tire would seem to be an easy thing to diagnose
Its has a hole in it and lost air
Check and no hole???
Fill with air, no leaking air sound
Next day its flat again, WTF!!!

And now a days labor is the expensive cost and parts are cheap, so shops don't want techs to do diagnostics in the old way, these days diagnostics usually consists of swapping out modules until problem is solved, lol

 

Oh yeah I’ve had my fair share of leaking tires with no holes come into the shop. It was normally the very first car when I walk in at 9am and I had to spend 45 min working on “patching” one tire 🤦🏻‍♂️ Glad those days are over.

I ordered the SJB from eBay. One guy was selling one that clearly had blue corrosion on the pins, like WTF. Hopefully the one I bought is good and doesn’t have any issues. It looked practically brand new but you never know until you get it in your hand and open it up. I appreciate all y’all’s assistance

 

So I replaced the SJB, I ordered one on eBay and when it arrived i opened it up to check for corrosion. It looked brand new inside, way better than the one thats on the truck. No change in symptoms. The truck still does everything that it did before