Hey! I'm a new Ranger owner and new to the forum. I inherited a 2001 4L V6 from my grandparents farm. It has had starting issues for a year or two and the family had multiple mechanics look at it, multiple fixes, but still having an issue.

From a cold start in the morning turning the key doesn't engage the starter. Everything else happens... fuel pump, ignition switch, interior power, etc. Starter relay is good. With the key on and starter relay pulled out, I can jumper the relay terminals to get the starter to crank. Here's the weird part though. While the engine will turn over from jumping the relay, it won't start up and run. I can't identify how or when, but eventually something changes and the truck will get going... but at that point it will start normally through the ignition relay or through jumping the relay.

To explain this a bit more, the truck sat for a good 4 months on the farm this spring because no one could get it to start. After jumping the relay a few times, which did not result in a successful start, I put the relay back and the next time I cranked it the truck started right up.

What's been done so far:
-replace digital transmission range switch/neutral safety switch
-replace computer
-replace fuel pump

After the truck is warm or after it has successfully started one time, it starts every time with no hesitation. I've only had the truck this summer, and during the hottest part of the summer the truck started every morning, so I am wondering if this issue is temperature dependent. While the issue is occurring I have tried to trace the circuit with a voltage tester and have verified full voltage is leaving the ignition switch and is making it as far as fuse 24. Beyond that it is difficult to test in the moment, but it is definitely not making it back to the relay. And all fuses look solid.

So the issue seems to interrupt the start sequence, keeping voltage from reaching the relay... AND it interrupts some other system that keeps the engine from running even if the starter is initiated... I could easily be wrong with my logic here, but I'm trying! Any thoughts or help is greatly appreciated!

 

Also meant to add - battery was replaced a couple times in the last 2 years from a separate airbag issue that drained the battery. The battery is currently in good shape.

 

Welcome to the forum

1999 and up V6 Rangers have PATS(passive anti-theft system)
Inside the handle of a PATS key is an RFID tag, it requires no batteries
When you put the key in the ignition and turn it on a metal ring(wand) around the key slot sends out an RF(radio frequency) burst which "powers" the RFID tag enough so it sends out its unique ID #, the metal ring gets this # and sends it to the PATS, this metal ring is just an antenna but is called a Transceiver, it has no electronics, just wired to PATS
The PATS compares this # to its list of 3 or 4 numbers programmed in at the factory(PATS Keys that came with the New Vehicle), if a Match is found then computer GROUNDS starter relay, so it works and also enables Fuel Injectors

If no match is found then starter motor will not work and even if bypassed fuel injectors would also not work so no start, which is what you describe

But..............if there is no match then you should see a fast flashing light on the dash, Theft light or a "lock" light, and you don't mention this
The bulb for this light could be burned out.
With key off and doors closed you should see a dash light flashing every 5 seconds or so, this indicates PATS is enabled, a deterrent to thieves
This is the light that would flash rapidly if wrong key is used, and if you let it flash for 1 minute or so(key on) it will then start flashing a code number, to tell you why it didn't "pass" the key being used

If you have a second key for the truck try it, while the RFID tags don't usually fail they can get weak, so don't work every time
If you have another Ford vehicle with PATS don't put both keys near each other on a key ring, because both may send out their #'s and so PATS sees a garbled #
Any Locksmith can check the key, and most can cut and add new PATS keys to the system

 

Thanks for the info and suggestion RonD! I'll try this in the morning

 

Wow - good info. Q: To check the system could you check the starter relay ground when the key is inserted?

 

Yes, you could pull the starter relay in the engine fuse box and use a test light hooked up to 12v
Turn key on and watch for test light to come on indicating PATS has Grounded the relay, you don't have to turn the key to START, just turn it to RUN(on)

The relay base will have 2 parallel slots on opposite sides, 85 and 86, one of these will be PATS ground and the other 12v from key in START position

Image here: https://www.12voltplanet.co.uk/user/...ng_diagram.png

There is no polarity, so Ford can use 85 or 86 as the Ground and 85 or 86 as the 12v


But rapidly flashing theft or lock light means key didn't work so starter relay won't be grounded and fuel injectors are OFF

But testing slot 85 or 86 for 12v when key is in START position will tell you if ignition switch to starter relay is working

 

My 99 4.0 auto has an intermittent starting issue. Engine cranks will not fire up. Engine code is security system. Sometimes it will start, just never know when it won’t. How do I fix this?

 

You should start your own thread, you should only post in someone else's thread if you are answering their question, just makes it simpler to find answers that way

Welcome to the forum

1999 was first year Ranger V6's got PATS(passive anti-theft system), this means it has "transponder" keys, and PATS reads that key when you turn on the vehicle
If the number inside the key matches 1 of the 3 keys vehicle came with when new, then you can start the engine, if no match or bad read then No Start

This is NOT an alarm system, just a No Start system, its "passive"

There is a THEFT LIGHT on the dash, it flashes every 5 to 10 seconds when key is off
When you turn key on THEFT light should come on and then go OFF, if the Key was accepted
If THEFT lights starts to flash rapidly then Key failed the test, and No start

You need the EXACT security code to see why key failed, there are 6 to 12 different ones, each means something different

For now test your battery voltage BEFORE starting the vehicle in the morning, or any time after it has sat for 6 or more hours
Needs for be 12.3volts or higher
If lower, battery is too old and voltage drops too low when starting so resets PATS and No Start
Low battery is the most common issue
Next is failing Transceiver, but code will tell you if thats the problem