Okay have an odd one,, my ranger has developed a gremlin,, started with battery light coming on then off quickly,, has morphed into random battery,,passenger air bag, and guage and fan speed drop offs, very random,, alt and battery seem fine by metering standards,, any suggestions?? please

 

Welcome to the forum

2005 and up Rangers got full digital dashes
And you can run them in Test Mode to see if they are working correctly and also if there are any "codes" reported, have pen and paper ready.

Look here: Mustangworld HEC Instrument Cluster Diagnostics

Charging system control runs thru the dash, so there could be a fault in the cluster causing alternator to reduce voltage.
Or it could be the wiring at the alternator, you don't say what engine you have in the 2008????

There were issues with 4cyl alternator wiring, 2 wire connector, 6cyl not so much

 

What does "seem fine by metering standards" mean? What were the voltages both running and off? Did you do a load test on the battery and alternator? Check for current draw with the vehicle off?

I can't count how many times "gremlins" turn out to be simple issues of a bad battery or alternator that a basic voltage test doesn't diagnose. Computer systems do not respond well to voltage fluctuations and can cause all sorts of insanity. So before pulling your hair out I'd verify the battery and alternator are functional with some good testing. Most auto parts stores do that stuff for free if you don't have the proper know tools.

 

Battery reads 12.46 v off , when truck is turned on before starting battery drops to 12.02 v , alt is functioning properly , truck running volts are between 13.5 to 13.9 volts.. alt is putting our 14.40 volts running (tested at wire coming off alt

 

Then as always... Do what RonD suggests lol. He is a genious and I never contradict his knowledge, I just always give a personal experience opinion. I live by occams razor, the answer with the fewest assumptions is usually correct.

 

Thanks I have taken his advice that self diagnose is awesome

 

4.0 soch