Hey guys...some weird activity from my Ranger popped up tonight. Haven't driven it since Thursday.

Anyway, I opened my drivers side door tonight and noticed my cab light was blinking on and off at a consistent rate. Also, my radar detector that's plugged into the cig lighter was blinking with it. And I also heard some sort of relay blinking on and off opposite the light. Same sound that is made as if your emergency flashers are on.

The truck is also dead...this is not a surprise. I've always had issues with this off and on...I've gone through 4 batteries in the last 3 years (free replacements, of course.) Everytime vatozone "tests" the batteries, they claim the batteries are bad...but I think its another issue. Maybe a bad battery ground. But I've not looked into it more.

I have not tried jumping it yet. Roomie isn't home so I have no one to jump it. Will have to try tomorrow morning.

Just found the blinking light activity weird. Its never happened to me...in any vehicle. What does this indicate?

 

Odd to say the least.

Could be a bad ground/power connection at the battery terminal.
Could be a bad ground to the body or frame.
Might be a random ground hidden behind the dash that's come loose.

My vote would go to Ranger Gremlins
Them suckers can pop up anywhere & anytime.

 

Sounds like either a bad battery or maybe charging system problem.

When the battery is close to dead or at least low enough on the power scale not to start the truck there is a point where the battery has enough power to energize the relays with the key on but not enough to keep them on and everything else reacts making you think there is a problem with the lighting or the dash lighting.

Get the battery charged and check things out, then if it is still happening Buggman’s approach is a good one to get started, grounding is one of the most missed diagnosed problem in a vehicle’s electrical system.
Remember the engine portion of the electrical system can draw 14.8 volts to run at its peak, anything less will cause poor starting, poor running, and poor gas milage.

Also, thinking... have the battery load tested and also the alternator to make sure it can handle the charging task. Some Shops can actually tell you if there is just leakage current causing you problems or not.
If there is a leakage problem, you will need to trace down the component causing it and fix it or put a switch in line to shut off the component when you leave the vehicle for a long time.

Another thing to consider is if the starter is weak and the connections are poor, this too can be a major problem when starting. To start a vehicle the battery has to put out all of the amperage it has in reserve, very high amperage and far more than most people thing it can even put out. This type of draw and poor connections will drain a battery almost instantly and appear to have been a bad battery.

 

Been there. Battery failing, been drained too many times, can cause this. It is an amperage issue, just enough to kick relays, but not sustain. Do a 'drain test'. Unhook the pos terminal on the charged battery, and put an ammeter across terminal and clamp. Note the reading. Above 20ma? There there is something draining you. Troubleshoot by removing fuses one by one and observe. This is how I found out that it was the alternator killing.

Took to AZone for test and it passed, but bought one anyway. Fault cleared.

 

Did the battery lose a cell or is it just old ?

You might want to check out the whole system with a load test to just be on the safe side.
Auto Zone does one of these test, just to sell parts, but it might give you an idea of the condition of the system.
Or take the vehicle to a shop you can trust and have them load test the charging system.

 

Jumped the truck once, and its been fine since. Has started strong since. But, the problem will creep up again.

Thanks for the tips guys. I'll keep all these in mind and do some diagnosing.