Grid Heat Hookup = Trigger of P0122?

[NightHawk]

Hello All,

 

Sorry for the story, but I am confused.

 

After reading all the articles on here with AC Noise Issues/Excessive alternator load, I began disconnecting my grid heaters (at the battery) during the warmer months (40F+).  Over the holidays, I took a trip to the mountains for some time in the snow so I hooked back up the grids and first start up the check engine light kicked on.  The engine was idling fine, but i noticed the voltage gauge took a long time to recover from the initial grid usage and every trigger (2 times) before I took it down the road to just check things out.  

 

At the gas station (5 miles away), I scanned the truck with my Smarty S03 and find a P0122 set with the companion P1693.  Scratching my head, i cleared the codes, re-fired and head to the mountains check engine light free/truck ran great.  At the end of a long ski day, in cold weather (17F + wind), the truck fired up no issues (or check engine light) but failed to kick onto high idle even though coolant was mid 50s at startup after sitting all day with IAT in the teens.  Once again, head out of the mountains check engine light free/truck ran great. 

 

This is where it gets odd, the next morning I head to a friends house (32F) and boom,  check engine light kicked on voltage gauge took a long time to recover from the initial grid usage.  Gritting my teeth (believing it was the same thing) I drove half way (truck was warm) and shutdown to rescan to get a 0122 set with the companion P1693.  I clear the codes, refire and check engine light kicks on followed by a extended (but shorter then previous) voltage gauge recover so I drove off in frustration for another 15 miles. 

 

After I got to my friends house, I disconnected the grids/double checked my battery cables (they were pretty tight) and cleared the codes.  At the end of a day out hiking, I fired up the truck to head back out with zero voltage gauge lag and no check engine light.  I have since only driven the truck with out the grids to zero issues.

 

SO - Fellow Form Members - Where should i start the diagnoses hunt?  I am leaning towards my alternator (I haven't checked for excessive noise in awhile anyhow) and the batteries are relatively new (replaced them in June).  I am afraid at some of the items in a P0122 (ECM/PCM) as that would be like.... a bad day.

 

 

 

[IBMobile]

Check the voltage out put of the alternator when the grid heaters are on.   I've seen it as low as 11.95V when testing.  Your alternator output may be low enough to trigger the apps low voltage when cold.  There my be some extra resistance, dirty/poor connections, in the systems exacerbating the problem.   Have you done the W-T wire modification?    

[Mopar1973Man]

If high idle is running either Cummins or Quadzilla will cause the grid heaters to run longer.

 

As for the error code typically a new APPS sensor will fix that issue.

 

I would suggest doing alternator AC noise test and replace the alternator if it marginal or failure. Then do the W-T ground mod.