got my alternator tested it is fine and so is my battery but it wont charge my battery any ideas

 

with the truck runing-test volts on batt terminals, if good the gauge in the truck may be faulty. did you load test both batts, main 140a fuse good, good clean terminals on the batts. check the volt output (b+ wire) on the alt-the pcm regulator may be bad

 

The most common suspect is the crank sensor, without a signal from it the PCM does not know the engine is running. The crank sensor is mounted just above the crank damper on the front of the engine just to the passenger side of center. Check the wiring going to the sensor, especially where it passes the belt and where it comes over the front of the head. Also check the connector in the harness for corrosion. Make sure the sensor is mounted securely and that the gap between the sensor and damper is correct. The gap should be 0.050" and should be checked with a non-ferrous feeler gauge. A matchbook cover folded once works OK. If your A/C is still blowing cold and your trans still shifts into overdrive this is not your problem.

The other common problem is a bad ASD relay. An easy way to check that is to swap it for the A/C relay. Of the three relays on the driver's fender, ASD is front and A/C is rear. If you don't find the trouble in the crank sensor wiring or gap checks, swap those relays and see what happens.

 

what if my ac doesnt work and i dont have over drive to start with

 

yep-crank sensor!

 

If you do not have overdrive then you also do not have a crank sensor. You could have a bad voltage regulator. Please fill out your signature so everyone knows what truck we are trying to help you with.

 

what else could it be

 

Forget what I said, you have an old truck. Change the regulator on the firewall.

 

where is it on the fire wall and what does it look like please could i also get this at a local parts store or would i have to call cummins also how sure are you that this is it or how would i check that this is what it is thanks

 

It's about dead center above the engine, it's a rectangular box with a wiring harness plugged into it. Every auto parts store has them.

 

alright thanks i will check it out today and let you know my find

 

So I Went To The Parts Store And They Have The Part Its 43 Dollars Is There Any Way To Check And Make Sure Thats It Before I Bye Or Are You Pretty Sure Thats Its Because Id Like To Not Waste That Much Money If Thats Not It Thanks

 

If the alternator tested OK then it has to be the regulator or a bad wire.

$43 is a rip-off for a voltage regulator. You can get one from Autozone for 1/3 the price.

 

Thanks For The Advice That Is What It Is I Went To Autozone And It Was 15 Dollars Alot Cheaper So Thanks A Million

 

2wdcumns247 what ended up fixing your issue?? i am having the same issue with a 92 w250. changed alternator, Crank Position Sensor, Water Temp Sensor, and even swapped out all the wiring Harnesses....