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Transmission Relay Question... (torque converter lockup related)


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Kind of an obscure question, as I was looking at the wiring diagram for my truck. (see link) @Dynamic If you have any input here... I would appreciate it.  I am trying to figure out why the trans relay is in line with the alternator field.  

 

If you look at the PCM on the left side, about mid way down you will see a GEN FIELD DRV, in dark green.  This field runs 100hz AC to the alternator from the PCM causing it to charge.  Lower you will see a GEN FIELD OUT, returning from the alternator to the transmission relay.  

 

Why would they do this?  Why not run the signal for the trans relay directly to the relay?  Why allow the non steady state voltage regulator to control the relay?  This seems like it should be simple and I am missing something.  

 

2002-Dodge-Wiring-Pg1.jpg

Edited by CSM
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11 minutes ago, Dynamic said:

The 100 hz signal is not an AC signal. It is a pulse width modulated DC signal running at 100 hz. A PWM signal allows them to vary the field current to the alternator, controlling its output.

 

The relay is wired into this system so that there is no power to the transmission unless the alternator is charging (aka engine running).

 

@CSM Here ya go :lol: I guess we should both request a refund ASAP

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The trigger for this is that my converter is hunting.  I dont think its my alternator, as its a new mechman and i dont see any significant ac coming from it.  

 

I wired the alternator field to a switch, to try to deactivate the alternator while driving.  Not unexpected, the hunting doesnt change when the alternator is not charging.  What is really odd, is that my trans shifts, locks up, and hunts with the alternator field (green wire) disconnected.  I am going to keep investigating.  

 

@Dynamic , or anyone else, is there a brief description of what the trans relay does?  I cant find it in my chrysler manuals or online.  

Edited by CSM
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8 minutes ago, CTcummins24V said:

Check your wires from the alternator. Make sure they are wrapped with something and not touching anything. That helped my unlock issue once.

 

Replaced with welding cable.  

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