Wtf??
 

Hey again,

Did a cab swap on my '78 k20. I re-used my old harness.
Now when I pull the headlight switch out my gas gauge drops to below empty and none of the cluster backlights illuminate.

I'm guessing I'm having some sort of ground issue here but I could use some direction on where to start.

Is there a master cluster ground wire?

My other interior lights are working, I still need to pick up a new cab ground strap. To be honest I'm not really sure how the cab is getting negiyie feed but since my other interior lights are working I don't think the the root of the problem.

Ps. Same cluster and same wiring harness that was in my old cab.

Thanks
Spencer
Posted via Mobile Device

Re: Wtf??
 

If it worked in the other cab it should work in this one, I'd start with the above...... Sometimes there's no rhyme nor reason when it comes to electrical.....

Re: Wtf??
 

I had one doing the same thing, turned out to be a bad headlight switch.

Re: Wtf??
 

I'll pick up a strap and a headlight switch tomorrow
Posted via Mobile Device

Re: Wtf??
 

I did put in the headlight switch from the new cab and the new cab used to be in a propane truck so the fuel gauge was NFG anyways. Hmm...
Posted via Mobile Device

Re: Wtf??
 

Did you maybe miss a ground that ties in at the ground "spider"?

Re: Wtf??
 

there is a spot about a foot from the cluster plug they all go down to one
should be easy to find , if you want to see it look in my 78 below ,when I did the cluster swap
Posted via Mobile Device

Re: Wtf??
 

The printed circuits on the gauges wear out from age, and can cross circuits at the connector. I'd check that too, if you have contacts lifting or the layers are separating you will need to replace it.

Re: Wtf??
 

Do they all just go into a single spade? Any idea off the top of your head if it's a solid black wire or not?
Posted via Mobile Device

Ed.
I just remembered that I have a harness from a '73 laying around, I'll take a gander at it in the morning.

Re: Wtf??
 

crazy glue will reattach them paths to the board
the radio heater anything grounded there seems to go to one "crimp"
and it carries as one wire from there
Posted via Mobile Device

Re: Wtf??
 

Radio heater? What the heck is that?
Posted via Mobile Device

Re: Wtf??
 

I think he forgot a comma.

Re: Wtf??
 

yup I did , can't remember where they all go but I read here it was good to add grounds, I did, I was swapping clusters, and needed to add even another ground,anyway for the small gas gauge.
it stopped my gauge from bouncing too.
find a black wire on the cluster plug follow it back and you will find it for sure!
Posted via Mobile Device

Re: Wtf??
 

here it is

Re: Wtf??
 

thanks bro!

I haven't had any time to mess with it since I made this thread and I'm heading out of town this weekend, but hopefully by Tuesday I'll have er' back in the shop. I have a feeling that there's a ground dangling somewhere.


On a completely unrelated topic Motornut, how did you lose 3 trucks while parked?

Re: Wtf??
 

I didn't lose them lol they were "close" to where i left them,or where the drunks left em
now i just buy shorter trucks...seems to be working!
the 78 and 87 were hit parked at work
the 88 in front of the house

Re: Wtf??
 

naturally,,, smaller target, harder to hit ! makes since to me.

Re: Wtf??
 

yup sure is smaller lol so is my GA he missed behind it
(next morning,78 Jimmys further up)
and now i got this great pic when somebody wants to know where the door wires go lol

Re: Wtf??
 

Finally got some more time to mess around with it.
Attached a body ground - nothing
Tried a headlight switch - no difference
Started monkeying with the cluster harness - the plug into the back of the cluster wasn't in all the way. D'oh!!

Problem solved!

Now I have to find the .69 amp draw. How the heck do I pull glass fuses without breaking them?!?!
Posted via Mobile Device

Re: Wtf??
 

cool,small flat head from the end
Posted via Mobile Device

Re: Wtf??
 

That was the first thing I tried, but some of them are seized in there and end up breaking in half if I can get an end to budge. Guess I just gotta take it sloooooooooow
Posted via Mobile Device

Re: Wtf??
 

changing them old ones might be a good thing anyway
20s were hard to find at a Canadian tire store,was surprised at that
all kinds of newer, but a couple of mixed packs with 1 -20
Posted via Mobile Device

Re: Wtf??
 

Lol I shredded the 20a radio fuse today and all I could find was a 15 and a 30, I went with the 15. Should be good, I run a power amp anyways
Posted via Mobile Device

Re: Wtf??
 

So the under-the-dash light draws about .67 amps :|

I knew the dome light wasn't connected but I forgot about that one. What I did learn is that the constant power on my tach draws 3-4 ma though for some reason. :s
Posted via Mobile Device