First time posting here but been lurking forever. I realized that there are more electrical gurus here after searching the posts, so here's my issue. And yes I'll be doing W-T's mod.

 

My alternator is making a bunch of AC current after my grid heater relays stuck on last summer. I didn't replace the relays until this week so I didn't realize the ecm wasn't doing a preheat or fuel pump prime pre-start. I also remote start every morning so I didn't hear the fass fire off. So my questions.

1, I'm having my spare denso alternator rebuilt. But should I find a Bosch instead? They aren't subject to diode failure as easily.

2, Will the ecm continue to further fail past this point or will a new alternator halt the progression.

3, Who and or with what does it take to reflash a new/used ECM. Dodge/Cummins, high end scanner, Smarty, etc. Bob Wagner said to find a 00-01 ecm, seems to be different info if its pnp with a 99.

Here's what happens when your grid heater stays on with a plastic CFM intake.
These questions Google and the forums haven't answered. Thanks for the feedback!

1. Do the W-T ground wire mod then do the PCM fuse protection mod. You can keep your Denso.

 

2. New alternator and mods above. Will stop all these issues.

 

3. Best bet is to call Auto Computer Specialist in Florida. They can test, repair and reflash your ECM. Comes with a warranty which Smarty does not...

I agree on the Denso.  All 3 of the gen 2's I am responsible for have them.  Yes the diode pack is a bit more expensive and not as easily replaced as the Bosch, but other than that there is no difference we have observed.

 

If you have a good local starter/alternator re-builder,  never get a "new" alternator (they are usually rebuilds from an unknown source),  have yours rebuilt!  The mods will help, but they still wouldn't stop the grid heater relay failure.  I think everyone needs to take a close look at their relays.  mine failed in a similar fashion as yours, but I luckily caught it sooner than you did.

35 minutes ago, Haggar said:

.  I think everyone needs to take a close look at their relays.  mine failed in a similar fashion as yours, but I luckily caught it sooner than you did.

This one of the reasons i disconnected mine. A few years back I noticed one of the protective caps on the 12v feed had melted slightly so I figured there was a problem. I just got used to driving without them. Probably redo mine after retirement. I have been around any real crazy temps so that helps.

Like here on the site I sell both styles of Denso diodes. 

Now if you do the W-T ground wire mod and the PCM protection fuse then your all set...

 

As for ECM and PCM rebuilders...

 

Edited February 17, 20205 yr by Mopar1973Man

Thank you for the replies! I'm told the ECM from 00/01's have a better build then 99's. If I get a used one is it plug and play or does it need to be reflashed? Being without my pickup for a few weeks will be hard if I send mine out to be rebuilt.

Here is how to change the diodes and brushes on a Denso alternator.

 

 

This is how to do a grid heater bypass that won't turn on the check engine light.

  

1 hour ago, Nrose07 said:

Thank you for the replies! I'm told the ECM from 00/01's have a better build then 99's. If I get a used one is it plug and play or does it need to be reflashed? Being without my pickup for a few weeks will be hard if I send mine out to be rebuilt.

Read from the bottom of pg. 2 and on to pg. 3.

 

Update. I got my alternator back from the rebuilder Thursday and after installing the issue is gone. I'm assuming it was from the long battery disconnect. Thanks again for all the help!