ECM Question

[GIT-R-DONE]

I have an external mounted voltage regulator, and found an ecm with it incorporated into the ecm. Would I have to do anything to the voltage regulator to make it work, or can it just be installed without problems?

 

[cerberusiam]

I believe the regulator is in the big block that mounts to the alternator and the PCM just allows it to work when it sees rpm's but not positive how they handled that.



At a minimum you will probably need the harness for the newer alternator and the connection to the PCM or some hacking of wires to make it work.

 

[Moab4x4]

Regulator Basics

I would keep the external regulator. That way if you need to replace it it would be cheap and easy. The wiring for the alternator field windings that control charge rate of the alternator for the ECM'd truck would have +12V to one side of the field (from a relay controlled by the ECM) and the other side would be grounded via the ECM. IIRC the wiring for the external regulator grounds one side of the alternator field and the regulator provides something less than 12V to the other side to regulate the field voltage. The key is in the harness. I had an ECM truck that I just disconnected the wires from the ECM to the field windings and wired up an external unit like on the older trucks. It worked fine. You just want to make sure that you don't have both connected to each other at the same time.



Basically, if you have 12V across the field winding of the alternator you get full output. If you put some fraction of that across the field you get some fraction of the output.



I had a regulator die on me on the road once and I just jumpered the field to the battery and to ground for a little while to charge the battery, pulled over, checked the battery to see if it was getting too warm, and disconnected the jumper for a while. Not really convenient, but I got where I needed to go.



Ken.

 

[abledog]

External Regulator

Would a crank position sensor be required to run a PCM with internal voltage regulator???

 

[cerberusiam]

Would a crank position sensor be required to run a PCM with internal voltage regulator???

In this case, the PCM's with the internal charge circuits do need a CPS. If they don't see a signal they won't activate the charge circuit. Now, if one could duplicate that signal then you would not need it but that could be problematic.