Roscommon charging problem...

[ccf460]

Roscommon charging problem...Update.. fixed it!

I followed the directions to the letter. I thought my alternator was bad, it checked at 14.7 volts on a testing machine, but on the truck , I only have 12.1 volts. The guy at the parts store said sometimes a bad bulb in the dash idiot lights can cause a no charge condition? Anyone have a guess on this one?

 

[mudman]

Yes on Gen 2 though.

 

[Skinny]

My alternator wasn't charging due to a bad connection on the twist bulb. After some cleaning and filing, the lights comes on when the key is in the on position and goes out after starting like designed. I think I am going to replace my light bulb bases to keep any connection issues at bay.

Obviously we know the alternator isn't charging in the vehicle but yet bench tests ok. 12.7 volts sound like it isn't doing anything because that is battery voltage.

Does your gen light come on? Are you testing voltage at the charging terminal on the alternator or at the battery?

 

[ccf460]

I am checking on the alternator and at the batteries. I don't have any idiot lights on at all, with just key on, or running.

 

[mudman]

Whoa... "Back the Truck up"... ccf460!!!! You say you don't have lights with the key on, or do you? Every thing should light up with key on, but not started. Also you have one battery that helps the starting and you have the run battery!! I would start like this..Fully charge both batteries, and then go from there. Well I should start by asking you is it 12 or 24 volts first off. 24 volts= back battery is charged by gen 2 or passanger side Alt., used in starting. front battery is run battery charged by gen 1 or driver side Alt.. You will need to check for "Exciter Wire" voltage too.

 

[Warthog]

Mudman - He has done the Rosscommon Equipment 12v conversion. No 24v anymore.

OP - You will need to trouble shoot the GEN2 circuit to make sure the passengerside excitor circuit is functioning.

Start with the very bottom fuse. replace it even if it looks good.
Then the GEN2 light socket on the cluster. Have you ever removed and cleaned the instrument cluster?
Then the GEN2 relay under the dash

 

[mudman]

Sorry I'm an Idiot!! Once again!!

 

[ccf460]

Mudman: I have never had dash idiot lights 24 or 12 volts. I do recall one of the "gen" lights flickering at a low idle, that went away once given a tap of the go pedal ( back when it was a 24 system). I am wondering if gen 2 has always had a problem, but when I had 2 it seemed to get by on just gen 1? I will pull the dash and look at the bulb/socket condition and go from there,with what appears to be no voltage being produced while the alt. is on the truck, makes me think something on the truck is telling the alt. to do nothing.

 

[Warthog]

In the CUCV and most of the GM products of that time period, the GEN bulb is part of the alternator circuit. If it doent's light up when the key is first turned on, then the alternator will not be energized and start making electricity.

 

[mistaken1]

I don't have any idiot lights on at all, with just key on, or running.

There it is (as warthog has already noted).

You need to find out why you do not have the gen2 light with the key 'on' (as warthog has already noted).

 

[cpf240]

Isn't the Gen2 bulb 24v in stock form? If it has not been changed to a 12v bulb, that could be the problem.

 

[ccf460]

The "gen2" bulb base was corroded, and probably never activated gen 2 in 24 volt form. I cleaned the base, the light comes on with igniton, goes out when running, and putting out 13.4 volts!

 

[Warthog]

Glad to hear that. Always goo to clean all the connectors on the instrument cluster.

BTW - The GEN2 bulb (194 ~3w) is a lower wattage bulb so it won't burn as bright as the GEN1 (168 ~5w) when supplied with 24v.

When it has 12v supplied to it it will just burn a little dimmer but will still work