I need help my 97 cummins 5 speed is not charging the batterys took alt had it tested and it is fine they said, it reads 10v or less on batts when running the gen light is on what can i do to fix problem i checked all battery connections and they are good ,any help would be a big help to me thanks

 

check crankshaft sensor, do any of the other gauges act up

 

Tach working?

 

Have your batteries load tested too. You can do a couple of voltage tests. With engine off, test the battery voltage. Then on large terminal on back of alternator, test for voltage. You should read the same battery voltage. If you read battery voltage then then alternator feed cable to battery is good. If you do not read battery voltage, there is a break in the system somewhere. Check the fuse.

Now start engine and check for voltage on large terminal on back of alternator. It should read 13-15volts. If you are getting that reading the alternator is charging. If you do not get that reading, the alternator is not charging in the vehicle.

 

all other gages work will check battery voltage on alt tonite but i am begining to think the computer is not telling it to charge

 

Did you check the big fuse as well?

Before you suspect the PCM, make sure you wring out all the wiring and connectors, it would be very rare for it to be the PCM.

 

thanks all it was the pcm and i adapted a gm 1 wire alt to my truck thanks for all the info