Alternator meter fluctuating

SWVA · 10-21-2009, 09:25 AM

I've got a '92 W250 with 280,000 miles on it, everything stock as far as I know. It wouldn't start the other morning, jumped it and checked alternator. It was only pushing 9v so I figured it was bad and had taken the battery down with it. Put a new battery and alternator in it. Starts fine, but the alternator gauge on the dash, as well as the "message center" flash on and off, and sometime the "Wait to Start" light will stay on for 1/2 hour or so. When all of this flashing, or lights staying on happens, the alternator gauge can fluctuate from 8v to 18v. Truck starts fine, runs fine. It also had this problem before the first battery died, but I had written it off as a loose relay, nothing to worry about. Is it possible that the flashing message center thing is killing my new alternator and battery? Or is it just coincidence?

Philip · 10-21-2009, 01:30 PM

You have an electrical issue some where. Start with the grounds first.

There is one ground wire that comes from the negative battery terminal to the raditor support. Where that wire gorunds to the raditor support there is paint under the screw terminal. Sand the paint off.

Behind the cargo light button one there is another ground wire for the dash unit.

Behind #6 valve is another ground wire. Do the same with it.

__________________
93 W350 w/duals, fuel pin turned, 6X.018" injectors, 4" exhaust, 3" air intake horn, Super HX40/16, auto(G56 soon), 3:07's axles, 2" skyjacker lift, B&W flatbed

khaoskustoms · 10-21-2009, 02:34 PM

Could be the pcm. The PCM controls the alternator.

Stephen

__________________
1994 Dodge Dakota Ext Cab 4x4. 4BTA Cummins, 15.09 @ 88mph 1/4 mile, 206hp @ 2700rpm and 446ft/lbs @2200rpm

SWVA · 11-05-2009, 08:35 PM

I worked on all the electrical connections I could find, cleaning up grounding points, making sure everything was tight... But I don't think that's what causing the problem. Today, I didn't have any flashing lights, but my alternator meter still read low (8v) all day. And when I came home from work tonite, after about 15 miles the battery was so low my headlights were almost nothing. Could this be a PCM problem? Or is there something else between my alternator and battery that could be intercepting/interrupting the juice from the alternator before it gets to the battery?

Old 'n Rusty · 11-06-2009, 12:46 AM

Are there any other electrical problems? Sounds like a PCM glitch. Some folks switch to an external voltage regulator like the older trucks had. I have never had a PCM but there is info out there on how to change to an external regulator.

You might want to edit your signature file to let us know the details about your truck. Is it a standard? Is it a 4x4? These details can help get answers faster.

__________________
91 (08-90) D250
5sp 2wd 497k VE 'adjusted', 3200 spring, Pyro, boost, 3.54 ,:thumbsup KN, 1\8" timing bump, 25mpg city 30mpg hiway 20mpg towing 6k 5'er
R60/7, Volvo 245 GL, f150 4x4 5 spd, Ram 318, MPG's are in Imp gal's

Last edited by Old 'n Rusty : 11-06-2009 at 12:48 AM.

SWVA · 11-06-2009, 07:55 AM

Thanks for the reply, Rusty. I think I've got the signature figured out so that it posts my truck info, but in case not, it's a 93' W-250, stock except for 4" exhaust and a wiring job that put the glow plugs on a homemade switch in the cab, rather than in the ignition. The truck's message center flashes on a off, intermittently, but that doesn't seem to be directly related to the battery charging problem. Sometimes there are no flashing warning lights etc. and the alternator still doesn't push a proper charge. Definately a direct relation to cold weather though. Once the day warms up, it pushes 13v just fine. Would the tech articles section be the best place to search for external voltage regulator info? I'm new to the forum. Forgive my ignorance.

__________________
93' W-250, reg. cab, 4" exhaust, 289,000 miles

***chris_cummins*** · 11-06-2009, 08:43 AM

seems like when i start my truck up in the morning and it is cold i hear something kick on and off and when it is on my meter drops big time all good once it gets warm tho

__________________
1992 dodge cummins diesel

mrmoparwl · 11-06-2009, 09:12 AM

chris cummins that would be your grid heaters for heating the air going into the intake for emissions reasons and to aide in cold weather starting, remember these engines have no glow plugs.

__________________
92 D250 Club Cab LE, BD converter, BD pyro, BD boost, Issapro temp, 16cm turbine housing, 100hp injecters, fuel screw bottomed, (not sure about star wheel yet), new linkage ends, 200 litre extra fuel tank.....so far (POM's)

***chris_cummins*** · 11-06-2009, 09:48 PM

Quote:

Originally Posted by mrmoparwl

chris cummins that would be your grid heaters for heating the air going into the intake for emissions reasons and to aide in cold weather starting, remember these engines have no glow plugs.

thanks man didn't know it it was normal or not

__________________
1992 dodge cummins diesel

Dan V · 11-06-2009, 10:08 PM

Quote:

Originally Posted by SWVA

..... sometime the "Wait to Start" light will stay on for 1/2 hour or so. When all of this flashing, or lights staying on happens, the alternator gauge can fluctuate from 8v to 18v.

I'm not claiming to be an expert in this stuff, but I'm wondering if the grid heater is staying on too long. That would pull your voltage down low, as you're experiencing. The low voltage with the grid heater on is normal, and not the sign of a bad battery nor alternator. The grid heater being on for a half hour isn't normal, unless maybe it's 60 below out.

So, the questions for the experts are 1) is this theory plausible, and 2) if it is, what would cause the grid heater to stay on like that? (Sticking relays, PCM issue, bad air temp sensor, ... ?)

__________________
'08 3/4 Mega Cab Laramie 4x4, 6.7L automatic.
305/65/17 BFG T/A-KO on stock suspension.
Extang Solid Fold tonneau cover, Line-X, plus other minor improvements.

SWVA · 11-07-2009, 03:04 PM

Thats a thought, Dan V. The low voltage reading doesn't always correspond to the "wait to start" light, but It definately does more often than not. Also, my grid heater was wired to a button in the dash, rather than through the ignition, by a previous owner. I don't know why. And of course, on warm days everything works like it should (ie. no Wait to Start light, no low volt meter) Could anyone tell me how I could test to see if the grid heater is running longer than it should? This truck is new to me, so I'm not really familiar with the guts, especially the electrical.

__________________
93' W-250, reg. cab, 4" exhaust, 289,000 miles

SWVA · 11-08-2009, 10:35 AM

Ok, I've checked my heating grid to see if it's stuck in the on position, and it's not. So I think I need an external voltage regulator. I've found a half dozen diagrams for how to wire one in, but I still have a question or two.

1. When I wire the regulator in to the two "small" terminals on my alternator, do I leave the little black box that's currently wired there out, and just secure it aside somewhere, or do I reconnect it?

2. Is it better to get power for the regulator from a 12v ignition source or direct from the battery? I've found info suggesting both.

3. Do I need a ground from the alternator to the regulator? If so, how? I've found info that says yes, and some that doesn't mention it.

Any help would be appreciated, I just don't want to fry anything and give myself more electrical problems. Thanks.

__________________
93' W-250, reg. cab, 4" exhaust, 289,000 miles

10-21-2009, 09:25 AM	#1 (permalink)
SWVA Newbie Join Date: Oct 2009 Posts: 6 Thanks: 0 Thanked 0 Times in 0 Posts SWVA's Truck Pics	Alternator meter fluctuating I've got a '92 W250 with 280,000 miles on it, everything stock as far as I know. It wouldn't start the other morning, jumped it and checked alternator. It was only pushing 9v so I figured it was bad and had taken the battery down with it. Put a new battery and alternator in it. Starts fine, but the alternator gauge on the dash, as well as the "message center" flash on and off, and sometime the "Wait to Start" light will stay on for 1/2 hour or so. When all of this flashing, or lights staying on happens, the alternator gauge can fluctuate from 8v to 18v. Truck starts fine, runs fine. It also had this problem before the first battery died, but I had written it off as a loose relay, nothing to worry about. Is it possible that the flashing message center thing is killing my new alternator and battery? Or is it just coincidence?

11-05-2009, 08:35 PM	#4 (permalink)
SWVA Newbie Join Date: Oct 2009 Posts: 6 Thanks: 0 Thanked 0 Times in 0 Posts SWVA's Truck Pics	PCM problem? I worked on all the electrical connections I could find, cleaning up grounding points, making sure everything was tight... But I don't think that's what causing the problem. Today, I didn't have any flashing lights, but my alternator meter still read low (8v) all day. And when I came home from work tonite, after about 15 miles the battery was so low my headlights were almost nothing. Could this be a PCM problem? Or is there something else between my alternator and battery that could be intercepting/interrupting the juice from the alternator before it gets to the battery?

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10-21-2009, 01:30 PM	#2 (permalink)
Philip 1ST GEN MODERATOR Join Date: Nov 2007 Location: Indiana Posts: 6,268 Thanks: 5 Thanked 248 Times in 227 Posts Philip's Truck Pics	You have an electrical issue some where. Start with the grounds first. There is one ground wire that comes from the negative battery terminal to the raditor support. Where that wire gorunds to the raditor support there is paint under the screw terminal. Sand the paint off. Behind the cargo light button one there is another ground wire for the dash unit. Behind #6 valve is another ground wire. Do the same with it. __________________ 93 W350 w/duals, fuel pin turned, 6X.018" injectors, 4" exhaust, 3" air intake horn, Super HX40/16, auto(G56 soon), 3:07's axles, 2" skyjacker lift, B&W flatbed

10-21-2009, 02:34 PM	#3 (permalink)
khaoskustoms Diesel Freak Join Date: Feb 2009 Posts: 546 Thanks: 6 Thanked 41 Times in 33 Posts khaoskustoms's Truck Pics	Could be the pcm. The PCM controls the alternator. Stephen __________________ 1994 Dodge Dakota Ext Cab 4x4. 4BTA Cummins, 15.09 @ 88mph 1/4 mile, 206hp @ 2700rpm and 446ft/lbs @2200rpm

11-06-2009, 12:46 AM	#5 (permalink)
Old 'n Rusty Diesel Freak Join Date: Apr 2006 Location: Edmonton Posts: 616 Thanks: 4 Thanked 24 Times in 22 Posts Old 'n Rusty's Truck Pics	Are there any other electrical problems? Sounds like a PCM glitch. Some folks switch to an external voltage regulator like the older trucks had. I have never had a PCM but there is info out there on how to change to an external regulator. You might want to edit your signature file to let us know the details about your truck. Is it a standard? Is it a 4x4? These details can help get answers faster. __________________ 91 (08-90) D250 5sp 2wd 497k VE 'adjusted', 3200 spring, Pyro, boost, 3.54 ,:thumbsup KN, 1\8" timing bump, 25mpg city 30mpg hiway 20mpg towing 6k 5'er R60/7, Volvo 245 GL, f150 4x4 5 spd, Ram 318, MPG's are in Imp gal's Last edited by Old 'n Rusty : 11-06-2009 at 12:48 AM.

11-06-2009, 07:55 AM	#6 (permalink)
SWVA Newbie Join Date: Oct 2009 Posts: 6 Thanks: 0 Thanked 0 Times in 0 Posts SWVA's Truck Pics	Thanks for the reply, Rusty. I think I've got the signature figured out so that it posts my truck info, but in case not, it's a 93' W-250, stock except for 4" exhaust and a wiring job that put the glow plugs on a homemade switch in the cab, rather than in the ignition. The truck's message center flashes on a off, intermittently, but that doesn't seem to be directly related to the battery charging problem. Sometimes there are no flashing warning lights etc. and the alternator still doesn't push a proper charge. Definately a direct relation to cold weather though. Once the day warms up, it pushes 13v just fine. Would the tech articles section be the best place to search for external voltage regulator info? I'm new to the forum. Forgive my ignorance. __________________ 93' W-250, reg. cab, 4" exhaust, 289,000 miles

11-06-2009, 08:43 AM	#7 (permalink)
*chris_cummins* Newbie Join Date: Oct 2009 Location: brookport il Posts: 23 Thanks: 0 Thanked 0 Times in 0 Posts chris_cummins's Truck Pics	seems like when i start my truck up in the morning and it is cold i hear something kick on and off and when it is on my meter drops big time all good once it gets warm tho __________________ 1992 dodge cummins diesel

11-06-2009, 09:12 AM	#8 (permalink)
mrmoparwl Cummins Fanatic Join Date: Jul 2009 Location: Prince George BC Canada Posts: 147 Thanks: 5 Thanked 5 Times in 5 Posts mrmoparwl's Truck Pics	chris cummins that would be your grid heaters for heating the air going into the intake for emissions reasons and to aide in cold weather starting, remember these engines have no glow plugs. __________________ 92 D250 Club Cab LE, BD converter, BD pyro, BD boost, Issapro temp, 16cm turbine housing, 100hp injecters, fuel screw bottomed, (not sure about star wheel yet), new linkage ends, 200 litre extra fuel tank.....so far (POM's)

11-07-2009, 03:04 PM	#11 (permalink)
SWVA Newbie Join Date: Oct 2009 Posts: 6 Thanks: 0 Thanked 0 Times in 0 Posts SWVA's Truck Pics	Thats a thought, Dan V. The low voltage reading doesn't always correspond to the "wait to start" light, but It definately does more often than not. Also, my grid heater was wired to a button in the dash, rather than through the ignition, by a previous owner. I don't know why. And of course, on warm days everything works like it should (ie. no Wait to Start light, no low volt meter) Could anyone tell me how I could test to see if the grid heater is running longer than it should? This truck is new to me, so I'm not really familiar with the guts, especially the electrical. __________________ 93' W-250, reg. cab, 4" exhaust, 289,000 miles

11-08-2009, 10:35 AM	#12 (permalink)
SWVA Newbie Join Date: Oct 2009 Posts: 6 Thanks: 0 Thanked 0 Times in 0 Posts SWVA's Truck Pics	Ok, I've checked my heating grid to see if it's stuck in the on position, and it's not. So I think I need an external voltage regulator. I've found a half dozen diagrams for how to wire one in, but I still have a question or two. 1. When I wire the regulator in to the two "small" terminals on my alternator, do I leave the little black box that's currently wired there out, and just secure it aside somewhere, or do I reconnect it? 2. Is it better to get power for the regulator from a 12v ignition source or direct from the battery? I've found info suggesting both. 3. Do I need a ground from the alternator to the regulator? If so, how? I've found info that says yes, and some that doesn't mention it. Any help would be appreciated, I just don't want to fry anything and give myself more electrical problems. Thanks. __________________ 93' W-250, reg. cab, 4" exhaust, 289,000 miles