Ive got a 1978 pickup that runs great, but the other day the CHG dash light came on while on rough road. The light is still on, and gets brighter when I turn the fan knob. Also the heat/fan stopped working.

Is this an alternator charge issue or is is possible the fan or control knob are shorting out? How do i check this? Also, the fuel gauge and temperature guage are acting weird... operating fine then not really accurate..

I started to mess around with it and now the radio stopped working.. Any tricks to remove the dash panel around where the heat controls and radio are mounted?

Thanks for any help!

-rich

 

I would check for a bad or loose ground wire. Make sure there is a good connection at all ground points and check the ground from the engine block to the frame and body. It could possibly be a fuse link going bad. Look for a place on the power wires coming off the positive battery post that is maybe a 1/2 inch diameter by 1/2 to 3/4 long and check for 12 volts on either side of the fuse link. The CHG light is the charging light for the alternator and a bad ground would/ could make it come on. I don't think a fuse link would make the CHG light come on though it could cause the issue with radio fan etc.

 

Thanks mwisham!
This is very useful. My wiring knowledge is limited but I think I can trace the grounds and check the volts at fuses..

It's interesting that multiple switches and devices fail..

I'm gonna poke around the vehicle and will get back to this post later today..

Cheers!
Rich

 

Check the brake light bulb and see if its out. Also, there is a relay on the right kick panel side that can cause issues as well.

 

Just for clarification, I am talking about checking the fuse links not the fuses. These are two separate things. The fuse links are in the power wires near the positive battery post. The fuses are inside the cab under the dash on the left side.

 

You'll know if it's the alternator, very soon. At least the one time I had one go out, very strange electrical things started happening, but the end result was that it slowly died on the way home, to where nothing electrical was working.

Bad grounds cause very strange things to happen, also. Either those devices of yours share a common ground (hard to say without tracing the wires or looking at the factory schematic) or yes, it's probably your alternator failing.

Nice camper by the way!

 

THANKS FOR THE HELP everyone!

just found out that the brake warning light is not working, so ill check the bulb and then try to track down a short in relay on the right side..

i did check the fuse link, but it seems to be ok, though i didnt get the meter on it.

The main grounds in the engine compartment seem ok also --- time to chase the others.

still trying ot understand the wiring diagram...

The ELF camper is super strong, so we'll make it though to the other side..

 

ok, so i took the dash partially apart and checked all the wires and bulbs, then checked the easy to locate ground connections. Not sure which one fixed the charge warning light, but it turned off and the fan blower started working again.

Still the radio wasnt working. I messed with it for a while, nothing.... after driving around the block i slammed the door and the radio started working... irony...

thanks for everyones comments and suggestions. it was very useful to track your leads.

-rich

 

Well, you've definitely got some kind of loose or bad connection somewhere. Might be "fixed" now, might not. But as long as you're cool with knowing it could resurface at any time (like the next time you slam the door or hit a bump ), then you're good!

 

The early cylinder-style fuses seem to have a lot less reliable connections than the later blade-style. I was chasing an intermittently inop blower fan that ended up being a loose/corroded clip for the fuse.

 

The brake bulb and charge bulb are tied together. Replacing the bad brake bulb usually fixes it. Glad you got her done.