kyncl

When I started my truck up the other morning, my check gauges light came on. My voltage gauge was at 8v. I checked it on my juice monitor and it showed 11.8v, then jumped up to 14.2v. It has been doing this for a few days now. Is this an alternator problem or something else. Thanks.

atc250r

That used to happen with my truck once in a great while. I found that letting it idle for a minute or two before hitting the road would usually prevent it. I also found that if I turned the truck off and back on, it would usually work after that. I would put my bet on it being the regulator, but from what I was told back when it happened to mine, the regulator is inside the ECU ($$$). I replaced my batteries about 2 years ago and my truck hasn't done it since. Go figure.

John

kyncl

I'm gonna have the batteries and alternator checked. How hard is it to replace the ECU, and where is it located? Or how do you test it? It started doing it in the cold weather.

atc250r

Just to make sure, it isn't your intake heaters cycling is it?

John

ado2b1

Mine has been doing that for several years. I've actually got several vehicles that do the same thing (my small car has a new rebuilt alternator). I've asked around a bit and one of the drivers at the company I work for, said something like the alternator not kicking on until its needed (or in driving conditions), or something to that effect. I can't swear to it though.

Bottom line, you should be completely fine as long as it does begin working after warming up for a couple of minutes or getting on the road.

I wouldn't worry too much about your ECU going bad. Mine only does it in cold weather (right around freezing and below), no problems the rest of the year.

kyncl

My only concern was the check gauges light. It was the first time it has ever done that. It does go to 14.2v after a minute or so.

atc250r

If the voltmeter drops below a certain level the ECU kicks the check gauges light on. I'd bet that if the engine temp one got too high or the oil pressure too low the same light would come on. I don't know for sure, its just a guess.

John

kyncl

I would guess that you are right also. I'm just concerned it is something that will leave my stranded, or worse yet, have to take it to someone to fix it when i'm out on the road. I try to fix all of my stuff myself.

John Faughn

It could be a lot of things , testing is the only way I spend money for parts , I would look at the ECU last , the least likely thing to go bad .
Load test the hole system , batteries , starter , ALT.
Clean all connections , to all of above , there may be corrosion that you can not see , use a preventative chemical to help keep corrosion from happening .
It sounds like [ after connections ] that the brushes are worn in the ALT. , there are kits available to replace , not too hard of a fix .
But test 1st .

kyncl

thanks for the advice. I will do some testing.

Dinner

Sounds like week batteries to me. My truck started doing the same this winter after a few nights of -20 Celsius without running. CEL comes on while I cycle the grids, gauge shows little less than the 12 (left line of the section). Truck cranks a little slower but once started gauge goes up to 14.5 +/-.

Boondock

Kind of off topic but how long have most people got out of their alternators?

I am at 119K and a 98 still with the original.

MARKY MARK

My alterator gave up a couple weeks ago with 97,000 miles. Voltage was dropping when I'd come to a stop but would go up with rpm's then a few weeks later, it wouldn't charge at all. Took it in and the shop said the alternator brushes were shot. They installed a remanufactured one.

Mark

blackimpala

I rebuilt mine @ 170,000 on my 96 CTD needed slip rings, brushes and diode pact. I put in new bearings just because. Cost me about $70. Works like a new one.
Floyd

surfram

Before you do anything else, check all of your battery cables including the grounds to the engine/frame. Is your passenger side battery overheating and spewing water/acid?