Alternator Field Connection Plug Source of Issue

[CowboyJoe]

2002 3500 Dually. 5.9 Cummins. Bone stock. 91K.  Works weekends and vacations pulling 37' Montana 5er. First post. Been reading and learning.  I really appreciate the position that these trucks were engineered and built to run and be maintained as stock and that anytime "we" start doing deletes, adds and creative wiring other issues are going to arise and are only a bandaid to fixing the real issue.  Anyway, I was having the torque converter issue at 55mph so decided to do an alternator rebuild and eliminate any AC leakage.  Rebuild went fine, installed the rebuilt unit and the alternator would not work, not quite 11.5v at the connection. Gauge would show low voltage, then drop to 8 volts and then the check gauges light would come on.  Crap!  Pulled the alternator, put the old rectifier back in and it worked. Bad rectifier? Perhaps, so I decide to purchase a new Denso alternator and quit screwing around. In the meantime, checking grounds, cleaning terminals, fuses, etc. No luck, still no charge.  New alternator arrived, installed. Still not charging!!!  NOW I'm worried. Seeing all this stuff about PCM's etc. and the dollar signs are flashing in my mind. What did I screw up? Fuses all ok. Wiggled the field terminal connector.  Voltage came up!! Noticed the wires where they enter the field connector are pulled to close to a right angle once plugged in.  

 

Pulled the connector and started to inspect the leads. Pulled to check on one lead as it entered the plug and it pulled out . Wires were broken right were the wires are clamped to the connector causing intermittent connection. Must have pulled apart more when I removed the field connector plug to remove the alternator.  Only continued to complete connection due to dumb luck. Anyway, repaired the connection and reinstalled. Fired the truck up and.........CRAP! still no charging.  Could it be? Pulled the field connection plug and checked the other wire (should not have assumed it was ok). Seemed solid, pulled a bit more and it separated. Also broken at the terminal connection inside the plug. Pulled the connector, soldered the wire and reinserted.  Fingers crossed, started the truck and success! 14 volts and working well.  Test drive and everything working great, no torque converter issues. I had two intermittent connection, broken wires at the field leads connection plug. 

 

I don't know if this is a common problem or not ,but it really pointed out to me that you have to chase every possibility and make sure that wiring and connections are solid and assume nothing.  This could have easily stranded me alongside the road had the vibration fully separated the broken connection.  It also could have cost a ton of money had I just thrown my hands up and gone to a garage and let them start replacing components piece by piece. By the way, I reinstalled the rebuilt old alternator and everything runs fine. No more phantom shifting and I have a spare alternator just in case. 

 

Anyway, thanks for the help and to all who share their experiences here. 

 

 

 

[JAG1]

Welcome to the forum CowboyJoe and thanks for sharing. There is a good helpful group around here and we have some excellent articles in our database. The more I understand about our second gens the more I appreciate them.

[Mopar1973Man]

Might want to look at my article about protecting the PCM from shorts. 

 

Then you might look into the W-T ground mod.

 

[IBMobile]

A good read thanks for the info.  The last time I was in a pick your part yard I found that certain alternator connectors for a gas Ram were the same as the diesel.  I cut the connector off of the harness and used it for testing the amp draw from the PCM.

[dripley]

Welcome. Certainly a good read. Finding the problem is 3/4 of the battle.