I have a check engine light on, dumped the codes, 41 Generator field not switching properly is what it is telling me.
Is this a sign of a bad PCM? or bad wire problem,
Can i fix this with the external voltage regulator, the truck is charging, since it always starts
Any Help?

 

If you google "41 Generator field not switching properly" you'll get a ton of answers. The first one says that the PCM tried to adjust the alternator voltage by varying the field current and got no result. It could be your brushes are going bad or maybe it's just a glitch. Reset the codes and see if it happens again.

Edwin

 

I don't know if the pickup on the balancer would cause that or not.

 

It definitely happens again, Looks from my google reading, that a external voltage regulator is in order,
Will the light on the dash go out after this is installed, or is there another way to make it go away,
Also, Does anyone have a part number for the voltage regulator or an application?

Thanks

 

A weak battery can cause the same thing. Have it all tested so as not to replace unecessary parts. The pcm expects to see battery voltage rise to a specific amount within a certain time. If not then the alternator field does not switch off, setting the code. Weak battery may be a very simple answer, but again, have it all tested at like AutoZone or something. They usually do it for free.

 

It could also be the ASD relay on the driver's fender. ASD relay is the front one of the three. Swap it with the one in the back (A/C) and see if it changes anything.

Even something as simple as corrosion on the ASD relay connections will kill the charging system and set a code 41. Don't throw parts at it until you've diagnosed it more fully.

 

I replaced the ASD relay, when i first got the truck since it was jumpered. It was also throwing a ASD code, then went away when I replaced the relay.
How would I go about diagnosing it, i am charging when i check it at the battery,

 

A quick trip to most part stores and have the batteries and alternator tested would be the first step. There is more to an alternator than just voltage. There is amperage, and proper wave form. If the diodes are out, it can mess with the computer as well, but not giving a true 14V DC. You have to start somewhere. Check the batteries. It has fixed more than one.

 

MIL is still on after the new ASD relay?

 

Yes, it is still throwing the code, it just went from 2 codes down to one, when you read them.
Haven't had a chance to try anything, went to carlisle this weekend

 

You will want to check continuity on the wire from the PCM to the ASD relay, as well as continuity from the ASD relay to the field.