Hi All,
New to the forum. So here's the scoop...
I've got an 03 Ranger 3.0 V6 automatic trans. that won't start... it tries but just won't the battery tsets good but reads low.voltage on the dash gage. Before this problem I started having some issues where she would over Rev either from 1st to 2nd or if I tried to gas it at high speeds... not only would it over Rev all the lights would get brighter, battery light would come on and it would slam back into gear if you didn't let off the gas in time. So the battery is good, alternator is good, new battery harness (all of it)... seems to me like it's clearly electrical someone point me in the right direction please!!

 

Welcome to the forum

Not much to go on?

Alternators can leak AC Voltage into the system which causes all sorts of issues with electronics, just FYI since all that is "fixed"

Do 50/50 test
Spray gasoline or Starting fluid(ether) into the engine
Try to start engine
If it starts and dies, then spark is OK but fuel pump or injectors are not working
If it doesn't start then Spark is the first problem to deal with.
50/50

Let us know what happens

 

The lights getting brighter would indicate that the alternator isn't fine.
It's over charging because the regulator is faulty.

 

OK so... battery tests good, alternator tests good.
I'm not getting any power to my coil pack and my battery gauge is reading almost nothing. Anyone have any ideas what would make the gauge read so low with a good battery?
so there's no spark for sure due to the lack of power to the coil pack.
The other fun thing that started is that now when I turn the key on to test things it's doin the old 5x5 your airbag system is all F'd up chime. Could that stop power flow?
All fuses and relays are good I've checked them all
what's really throwing me is the gauge on the cluster reading so low (I've also checked the cluster resistors etc. And all are within range of specs)

 

There is no "battery gauge", the gauge on the dash is just hooked to dash 12v and ground, so if it reads low then power isn't getting to the dash, simple as that.

So you have a bad connection.
Good battery voltage is 12.3 to 12.8volts
12.2v or under is discharged or bad battery
You say "good battery" but don't mention its voltage, what is it???

2003 Ranger should have 2 cables coming out of Battery Positive terminal
Larger one goes to starter motor
Smaller one goes to engine Fuse Box <<< this is the one that powers the whole truck and engine
Check voltage in engine fuse box, pull out Fuse 11, 50amp, test voltage it should be EXACTLY the same as battery voltage.
This engine fuse box powers the cab fuse box, so bad connection here means no/low power everywhere else

Battery Negative terminal cable can have 2 or 3 cables, larger one will run to starter motor's attachment bolt OR to the engines block, this MUST be a good connection, clean and tight.
The other 2 or 3 smaller cables will run to Rad support(ground for head lights and horn), inner fender(ground for relays) and frame(ground for taillights)

And on the back of the drivers side head there will be a Ground strap, to the firewall, that's the MAIN ground for the cab electrics, needs to be clean and tight or low voltage in cab.

GROUND is same as power(12v), a bad ground shows same "low" voltage as bad 12v connection, no difference, people often over look this and focus on 12volt side

 

Battery voltage is 12.5 straight off the battery and at fuse 11 with key on... I just replaced the cables I'll try cleaning the starter contacts more and see if that does anything.

My ground goes to the rad., engine block, and starter. This will be a quadruple check of the grounds. The cab has power, radio turns on dome turns on chimes sound normal locks and windows work at normal speed...

it cranks at normal speed also not too fast not too slow. My dad is a mechanic for 30+ years and he's even baffled. He is worried the computer took a crap.

Thanks Again for the input!! I WILL figure it out!!!!

 

PCM Relay or PCM Diode?

In engine fuse box is the PCM Power Diode, it gets 12v from CAB Fuse box #19, 25amp, when you turn on the key.

This 12v activates the PCM Relay
PCM relay sends 12volts from engine fuse box #7, 30amps, to ALL the engine electrics.
PCM relay powers:
PCM(computer) of course, lol
Coil pack
All injectors
MAF heater
Fuel pump relay(not pump)
EVAP
AC Clutch relay
And a few others I can't remember

So no 12volts at the coil pack's red wire means PCM Relay is not passing on 12volts to the coil pack
Test red wires at injectors, they get 12v from same place, same wire really, just spliced into all over the engine bay