Engine/Transmission (1994 - 1998) Alternator not charging

[Monroefiredog1]

My charging system is not charging, I have had the Alt. checked off the truck, it showed it was charging about 13. So I replaced the Eng. Speed Sensor(Crank Sensor) that did not help. So I guess that the ECM is bad huh? Does anyone have any ideas on what else it could be? I need some help here!!!





Thanks





__________________

1996, 2500, Club Cab, Stock eng, rebuilt auto trans, will be getting KDP fix soon, then GAUGES, then POWER!!





Eng. Speed Sensor

 

[DSiemens]

Been through a similar problem on a 1995 Ram. All of a sudden, alt quit charging, tach and speedo quit too. Problem was a loose connection at crank sensor. The pcm will not turn on until it receives a signal from crank sensor. If you still have tack and speedo, it is not likely to be a pcm problem. About the only time they fail is when guys power wash them and water seeps into them.

 

[tbrudder]

I seem to recall something about the battery temp sensor possibly causing this. IIRC, this generally happened when someone put something like an Optima battery in place of the OEM, and used a spacer under it to make the hold-down fit. Supposedly, by taking the battery away from the temp sensor contact, the ECM thinks the batteries are frozen, and sets the charging voltage to zero.



Then again, this might just be an issue with the 24v, but it might be worth checking...



--Ty

 

[trucknut]

Not Charging?

While you were changing oil if the back of the alternator was bumped(filter wrench, ratchet, extension)You may have killed(by grounding) the ECM that signals (12v) the alt to charge. Run a 12v jumper line from your battery to the back of your alternator, I think its the bottom post and nut. If this excites your alt, then thats the problem. The alt should cycle in and out, meaning its internal regulated. Test with a volt meter,should be 13 to 14. 2 volts. If your alt is REGULATING you can proceed to hook up the jumper permanently, and save the cost of an ECM. (If the alt is not internal regulated an EXTERNAL regulator MUST be installed)

This jumper line will draw power constantly and must be connected to a fused ignition-on power source. You can get away with the jumper line in a temporary situation. Just un-hook the jumper if the engine is shut down longer than 12-24hrs.

My 9812v alt. is internally regulated(not regulated by the ECM) and has been wired this way since 1999 with no problems.

 

[edmeyers]

Monroefiredog1



When i first got my truck the batteries looked like they had been sitting out in the weather for about a year but i figured i would see just how long they would last. n e way one day the lights on the instrument panel came on like the engine had died but i was still crusing at about 65 mph so i knew that wasn't the problem.

i had the alt tested and replaced both batteries. but when they ran down again i had the same problem finally went to an autozone near my work and ask if they knew what was wrong.



turned out to be the fuse in the box by the driver side batt. it is a dealer only item but it did resolve my problem.



the fuse is bolted between the charging cable from the alt. and the batteries close to the engine side of the box.



hope this helps