HOW TO DIAGNOSE A CHARGING SYSTEM. COMPUTER OR ALTERNATOR FAILURE? 2nd GEN CUMMIMS.

Testing a computer controlled charging system on a 1999 Dodge 5.9l Cummins

[@SprayWayCustoms]

You a Jack Of All...keep up the great work and videos

[@swc-diygarage]

Thanks SprayWay. Got a couple more technical videos before I get into cutting and welding body and paint.

[@ronnychaves2917]

Thank you

[@swc-diygarage]

Hope it helped. Thanks for watching.

[@redfuel6bt]

Please change the oil filter! How long does a oil filter have to be on a truck to get that rusty? Very informative video thanks!

[@swc-diygarage]

Well it's a long story but the pervious owner put 20,000 KM on this oil change before it got parked for 5 years. The fuel filter looks real bad all so. A full service will be done once the body is restored and ready for the road. Thanks for watching much appreciated

[@projectramlife819]

What happens if the green wire does not show full battery voltage?

[@swc-diygarage]

May not activate the relay that closes the field in the alternator. Should be no voltage or battery voltage. If not you have other problems.

[@projectramlife819]

@@swc-diygarage thank you for you reply. I've been on a hunt with my alternator it seems to come on and off when it wants to. Also lost my fuel gauge not sure if they both are part of same problem. Hopefully it's not my pcm but I'm thinking that that just might be what it is. My wait to start doesn't com on Immediately as soon as I turn on my key comes on like 5 10 seconds later.

[@swc-diygarage]

@@projectramlife819 from what I understand the wait light does 2 thinks. Gives time for the grid heaters to heat up and the ecm to communicate with the pcm before you crank the engine.

[@OutdorsDanny]

Mine is making too much power. I already replaced the alternator not sure what to do now.

[@swc-diygarage]

How many volts is it producing?

[@Fun-under-the-hood]

⁠@@swc-diygarage hey I can answer this question, mines doing the same thing, my needle pegs up to 18 V , rides like that for about 20 minutes and then comes back to 14 for about 10 minutes and then pegs again. when I start it in the morning I can drive 30 miles no problem. Then in the evening when it's about 80° out, I start the truck let it warm up for five minutes and the needle pegs and starts doing that intermittent issue something about it makes me think that temperature has to do with it. I didn't have this problem till it started getting in the 80s here. tomorrow I'm gonna test that the computers working like you showed here in the video. I've checked my batteries while the needle is pegged and the truck is running and I'm getting 14.9 V then it will drop to 14.6 sporadically bouncing between 14.9 and 14.6. Right on my alternator, which doesn't look OEM there's a tag that says must be externally regulated. I do have an external regulator. Also looks non-OEM. Whoever i bought the truck from must've done an alternator and external regulator. any help would be great.

[@swc-diygarage]

@@Fun-under-the-hood a voltage regulator is the quick and easy fix if the computer quits but i would think the alternator shouldn't be putting out high voltage

[@adrianlowe20]

Probably should change those ends of the battery cables and clean up those nasty looking connections

[@swc-diygarage]

I have cable blocks for the battery posts putting them on when it gets rewired. Thanks for watching.

[@myviews469]

Wait a minute you did nt have battery connected and alternator is bad how did you keep engine on?

[@swc-diygarage]

Truck is set up for 2 batteries running in parallel. I'm only using 1. The connectors you see during the test are form the missing battery.

[@myviews469]

@@swc-diygarage OK but if those batteries running parallel. then that means when you meter check green wire the current was coming from the other connected battery?

[@swc-diygarage]

@@myviews469 yes

[@myviews469]

My field wires are red and brown coming from PCM to Alternator I did what you did and on the meter 10.69v between brown wire and positive of the battery and between red and negative of battery 0.03 what do you think?

[@swc-diygarage]

@@myviews469 from what your telling me the computer is switching the ground but do not have battery voltage going to the alternator. Test the red wire back farther in case there's a break in the wire. All the way to the computer if you have to.

[@themechanicman3865]

24 valve n 12

[@swc-diygarage]

Yes.. Thanks for watching and commenting.