Powerstroke battery light

[NotMatt]

'96 7.3L Powerstroke. It has about 1 year old motorcraft batteries that the Ford dealership I bought it from put in. Has a 1 year old NAPA alternator that I put in myself right after buying the truck, since the old one went out on me in Goldbar.

The battery light keeps coming on, kind of randomly... but it seems to come on a lot when I first start the truck in the morning, and when I accelerate. Sometimes it does, sometimes it doesn't. The batteries are staying charged, it's putting out good voltage at the alt (it's been doing this for a couple months).

Took the alt. in to NAPA and had them test it, they said it tests out fine. I checked my battery cables on both batteries, cleaned the terminals, everything looks good here. Traced the grounds back and cleaned them as well.

What next? I haven't load tested the batteries yet, I'm going on the assumption that they're probably ok since they're only a year old (yeah, I know, I know). Any thoughts?

 

[boxboy]

is your ground going to the engine?

How about the ground from engine to frame?

 

[zukkev]

Go to Napa and get another one---should be warranty...the bench testers don't give you true dynamic testing---they only give you an idea... Of course you need to check all your powers and grounds for any voltage drops, but my $$'s on the Alternator Matt. Also, which line did you buy? The premium, or el cheapo...

 

[NotMatt]

Go to Napa and get another one---should be warranty...the bench testers don't give you true dynamic testing---they only give you an idea... Of course you need to check all your powers and grounds for any voltage drops, but my $$'s on the Alternator Matt. Also, which line did you buy? The premium, or el cheapo...

Whichever one costs 220 bucks at 8AM at the NAPA in Monroe on a Saturday morning when I left the truck idling outside and "just wanna go wheeling, not replace an alternator today, damnit".

I don't even remember if I gave them my phone number for a warranty or not.

The parts guy at the local store here said to check the belt tensioner too... might not be holding enough tension on the belt, under acceleration and cold start.

 

[TreeClimber]

Check you glow plugs. See how much draw they're pulling now that it's starting to get cold again

 

[shrtscrplr]

sounds like a bad diode in the altenator. dont trust napa or autozone or schucks to test our electrical ****. they sell parts for a reason and they always have people work on their own rigs.

 

[zukkev]

Whichever one costs 220 bucks at 8AM at the NAPA in Monroe on a Saturday morning when I left the truck idling outside and "just wanna go wheeling, not replace an alternator today, damnit".

I don't even remember if I gave them my phone number for a warranty or not.

The parts guy at the local store here said to check the belt tensioner too... might not be holding enough tension on the belt, under acceleration and cold start.

Check on the Alt...most units from Napa, will have a sticker on it, the premium is "Power Supreme"---lifetime warranty. Oh yeah, they come in a blue and yellow Box!!!:redneck: The second line alts are usually in a gray and yellow box...which still have a 3 yr warranty...
as for the tensioner not holding the belt tight, your belt would squeal fiercely if this were the case!!! See, the alternator is working overtime when cold trying to recharge the batteries after startup, cuz the glow plugs draw upwards of 200 amps on initial on-time...:awesomework:

 

[zukkev]

dont trust napa or autozone or schucks to test our electrical ****. they sell parts for a reason and they always have people work on their own rigs.

What??? EVERY place you buy these parts from are there to....you guessed it, SELL PARTS!!! Where do you get your info...it's not who tested it, it's what they use TO test it...

 

[Robinhood]

I am not sure on the years but some of the older medic units , E-350's, had a relay on the right side of the rad that we had alot of trouble with turning on the batt light. Last time I tried to get one Ford said they were not availible anymore so you would have to wire in a standard relay.

 

[NotMatt]

Just as an update... yesterday I looked at the battery cables some more and noticed that the cable running from the driver's side battery positive to the passenger side battery positive was extremely corroded and bulging under the insulation right where it meets the terminal... I cut the insulation back and found it was corroded and nasty a few inches back into the cable. The whole positive cable is one piece with the terminals and all from the driver's side battery to the passenger side and then down to the starter and main relay box. I should have a new one from Ford today to the tune of $120.

I hate to admit to spending that much on a battery cable, but it's all one piece and the cables can't be replaced separately, and I didn't feel comfortable just buying a "wing nut" terminal and making some sketchy new connections on a rig I want to be reliable and dependable.

We'll see if it fixes the problem. I would imagine the alt trying to charge through a crappy corroded connection might cause issues...

I am not sure on the years but some of the older medic units , E-350's, had a relay on the right side of the rad that we had alot of trouble with turning on the batt light. Last time I tried to get one Ford said they were not availible anymore so you would have to wire in a standard relay.

Hmm... interesting.

 

[zukkev]

Just as an update... yesterday I looked at the battery cables some more and noticed that the cable running from the driver's side battery positive to the passenger side battery positive was extremely corroded and bulging under the insulation right where it meets the terminal... I cut the insulation back and found it was corroded and nasty a few inches back into the cable. The whole positive cable is one piece with the terminals and all from the driver's side battery to the passenger side and then down to the starter and main relay box. I should have a new one from Ford today to the tune of $120.

I hate to admit to spending that much on a battery cable, but it's all one piece and the cables can't be replaced separately, and I didn't feel comfortable just buying a "wing nut" terminal and making some sketchy new connections on a rig I want to be reliable and dependable.

We'll see if it fixes the problem. I would imagine the alt trying to charge through a crappy corroded connection might cause issues...



Hmm... interesting.

Too bad your not closer---I'd hook ya up (we build our PSD cables...have all the proper connector ends)...

 

[NotMatt]

Man that cable is kind of a PITA to replace... started that project last night not realizing how long it would take. Anyway, battery light has stayed off so far...

Only problem is, now it seems like my glow plugs aren't doing their job... took forever to start this morning even after waiting for the light to go out, and the voltmeter didn't do it's normal thing where it sits way down to the left for a minute after starting the truck.

Where's the GPR located at on OBS powerstrokes?

 

[zukkev]

Just above the passenger valve cover next to the filter housing, should have one big wire (black with orange stripe IIRC) coming in, and two smaller ones off the other big lug ---and two even smaller wires (red IIRC) going to the small contacts....

 

[NotMatt]

Yep, turns out I'm a dumbass and put the feed for the glow plug relay on the wrong side of the starter relay on the fender. All fixed.

 

[zukkev]

Yep, turns out I'm a dumbass and put the feed for the glow plug relay on the wrong side of the starter relay on the fender. All fixed.

:redneck:

 

[jeepermc]

Lucky that bad cable didn't short out and burn the truck down....I was gonna throw out that there is a heater hose that rubs on the wiring plug for the alternator than can cause problems but it sounds like you found it...Might wanna make sure that heater hose isn't rubbing on the alt wires just the same.

 

[NotMatt]

Lucky that bad cable didn't short out and burn the truck down....I was gonna throw out that there is a heater hose that rubs on the wiring plug for the alternator than can cause problems but it sounds like you found it...Might wanna make sure that heater hose isn't rubbing on the alt wires just the same.

Yeah, I fixed that when I replaced the alternator last year. It was rubbing some of the insulation away, so I just split a piece of hose down the middle and put it over the wires.

For anyone who's curious, the battery light has not come back on since I replaced the cable. :awesomework: