So I went to go out. My truck started fine and off I went. couple minutes down the road and ding on comes the check gauges light and my voltmeter goes all the way down.

So I came back home shut it off checked the terminals and wires with a voltmeter thing and Ive got 15 point something volts at both batterys. So I cleaned the terminal and wires really good start it up everythings fine.

Couple minutes down the road same thing happens. What else should I check?

Thanks in advance, Frank

 

Ok I got codes

PPCU
P1682

PECU
P1693

 

Ok I found what they mean

p1682 charging system to low

???? Is my alternator bad? Becouse the gauge show its fine then all of a sudden it just drops down to nothing.

p1693
DTC detected in ecm or pcm

do I need to buy a code reader to find out what code it is?

 

The first thing I would do is clean the grounds good. I know it sounds silly but I did it and it solved alot of weird problems for me.

One ground is on the passengers side block, the other is on the drivers side frame.

 

EverydayDiesel is right on the grounds. Same thing happened to me about 2yr ago and that fixed my problem. BUT I started having the same problem again about 2 weeks ago and cleaning the batt terminals did not help. I have determined that my problem now is the grid heaters are not turning off and for the time being I have disconnected the heaters and so far the battery gauge is working fine now. I think the heater relays are bad so I'm going to get around and replace them or just leave the heaters disconnected. Hope this helps.

 

my voltmeter shows normal untill about 25-35 mph and then it drops down to nothing. I will clean all grounds. but i think that its charging just not reading or something becouse I drove to and from work and to the bank with out killing the batteries. I was thinking maybe some sensor or something to do with the grid heaters, since it drops down after it gets to like 30mph.

 

I've been driving for 4 days now after disconnecting the grid heaters and the battery gauge has been charging every day without a glitch. I plan on pulling the heater relays out in a couple of days and check them out.

 

where about are the relays for the grid heater? in the fuse box thing under the hood? thanks

 

They are mounted on the driver's side fender well. Just trace the wires from the grid heater down to the fender well. Real easy to get to.

 

Ok for starters the multi meter i was using wasnt working right if I held it on the battery it just kept going up and up. so I checked with two other ones and i have a little over 12 volts at both batteries.

This time when I started it up when the grid heaters turn on my radio cuts out, taillights go out and headlights dim almost completly out.

So I took off the altenator and am going to get a new one in the morning. See if thats the problem. Just seems weird that it dosent drop down on the voltmeter untill like 25mph. O well Ill see if that fixes it and go from there.

 

O and when i took off the alternator I discovered one of the bolts had worn right through the alternator housing and half way through the bolt. Check it out.

 

Any solution to your truck problem? Mine has suddenly developed the same issues.

 

I think your alternator is moving when you get up to speed and then not charging due to belt slip.

With that much wear on the bolt and in the case that's a huge amount of travel.