gen 1 light on with heat

[nighttrain2006]

gen 1 light comes on when heater fan is on ( the gen 1 light is very dim) not full red like on starting. is this normal?

 

[Mike_Pop]

Check your belts on the alternators, check the connections on the alternators. I had a similar problem and found that all the connections and belts were fine but I had a broken post on one of the alternator terminals. It wasn't found until I pulled on the wires.

Gen 1 is the driver's side alternator. I marked both of mine with a Sharpie for future reference.

 

[nighttrain2006]

thanks ill give the alt a good check, that alt looks very new. must have been replaced before i bought the truck. I have a 86 m1009 blazer

 

[jbolty]

FWIW

I just had to replace a diode set in one of my alternators (left one) and in the process of searching for information about them I found a mention of the exciter circuit somehow being wired off the heater circuit. Can't find the link now but I may have it at home.

 

[1stDeuce]

Hey, I was just noticing that exact thing... Even on civy chevys of this vintage, it looks like the fuse in the box that's labeled "HTR" is also the one that feeds power to the exciter terminal on the alternator. (Alt 1, or 12V alt on a CUCV)

Dim usually means it's not keeping up with draw... Does it get brighter as you turn on more 12V stuff?? Check the connections, do a load test across the forward battery. this is the battery that supplies 12V to the truck. Your alt should be keeping this battery above 13V with the engine running, even with the heater on high and the headlights on.

C

 

[nighttrain2006]

yes the gen 1 light gets slightly better with the more 12volt stuff i run, but is still very dim

 

[HeadWizard]

gen 1 light comes on when heater fan is on ( the gen 1 light is very dim) not full red like on starting. is this normal?

Ummmm.... don't use the heater fan?

Very sorry, I just had to.

 

[Mike_Pop]

RE: Re: gen 1 light on with heat

My recommendation:

Pull the alternator and take it to a shop that can test it and service it. I don't mess around with trying to figure out loads anymore. I let the professionals do it. It saves a lot of time and head scratching.

 

[NC Cucv]

Having a similar problem with my 1984 CUCV. When I turned on my heater the other day it stopped working and the gen 1 light came on. When I turn off the heater the gen 1 light goes off. And I have noticed that my volt reading does not seem to power up to the green as well. I have replaced my blower motor about 6 months ago, put 2 new optima batts in about 7 months ago. I also have had my gen 2 rebuilt after it locked up about 1 year ago. All belts are also new. Any suggestions
would be of great help. I am new to this sight and it is great, lots of helpful info.

 

[86Chev1028]

I went through the same exact situation. It would be dim and would get brighter when increasing the blower. It'd be off without the blower or lights on but would blink when using the blinkers. I drove it like that for quite a while right up until the GEN 1 light stayed on after I shut the truck down and removed the keys from the ignition.
I then got both alts rebuilt and all is happy and well again.

 

[sierrajcharlie]

Sounds dumb but pull the fuse and clean it up/replace. Had the same issue a year ago in my new to me unit. Read here to check the fuse and it solved my issue. The fuse looked fine til I tried to shine it up a bit, then it fell apart in my hands. I had checked the belts, got the alts load tested, load tested the batteries and a couple of other things before that! Cheap!

 

[pearc]

this is all good info that i need to check ,ny gen 1 light came on dim this am real dim could smell something like burnt fan belt stop and checked and all was good light went out till heater was turned on then gen 1 came on bright turn hearter off light goes off

 

[pbrstreetgang]

My truck is doing the same thing, and the fuse box is eating a fuse a day. It burns them up, melts them and the heater will only run for a little while before this happens. Where do I start looking?
I am going to pull my heater control box to see if that is the cause.

 

[Warthog]

Pull the purple wire off the blower fan and see what happens.

Also check the fan switch on the dash. They are known to get dirty and go bad.

The Heater and GEN1 exciter circuit are indeed on the same circuit. There are two brown wires on the left side of the fuse socket. One that goes to the fan switch on the dashboard and one that goes to GEN1. WHy they designed it this way I have no idea.

 

[jatonka]

Thanks, my M1008 lights the Gen 1 light bright as soon as I turn the fan on any position, I will start checking. Mine also doesn't run the fan in any position, I have been thinking maybe there is a critter nest in it but haven't had time to check, it's a spare CUCV for the future. JT

 

[choll]

I had a problem similar. I along with members who happened to be in Las Vegas spent hours trying to figure why my front battery was not charging after a hundred hours of trying to figure it out I converted it to 12volts. My heater fan did not work not a big deal didnt need it in vegas. To make a long story short i was working with the dash pad off while off i decided I was ging to work on the heater. Come to find out the fan switch was totally burnt, I replaced the switch now everything works as made.

 

[pbrstreetgang]

Thanks warthog, 6$, O'reillys, a new heater switch, and a cool wife to watch
Three kids on Valentine's day while i installed.
Gen 1 light off, no burnt up fuses, and I have heat!
Battery is also charging

Thanks again

 

[Warthog]

Another satisfied customer.

Sometimes us old farts happen to get it right....

 

[pbrstreetgang]

Back again. Same problem, different cause. Evidently when my heater switch was going bad it was melting fuses at one a week. pulled my fuse block apart and where the fuse goes in for the heater, the fuse connector on one side is not there (just chunks of metal) and the plastic is melted. I am going to wire to another (empty location) on the block but I need fuse connectors and dont know where to get them. This explains why the heat would come on, gen 1 light would go out if I wiggled the fuse in there, I just hadn't had the time to dig in look.

 

[Warthog]

The heater fuse has three wires. The orange wire on the right is the supply side (comes from the ignition switch) and the two brown wires on the left are the load side for the heater and GEN1 circuit.

I don't know where to buy new terminals but HAWKMAN may have a used fusebox for sale.

You also could bypass the box and install a in-line fuse.