Wtf?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

willett · 08-27-2013, 05:10 PM

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
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Restrorob · 08-27-2013, 06:25 PM

Quote:

Originally Posted by willett

I still need to pick up a new cab ground strap.

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.....

07XCSBZ71 · 08-27-2013, 06:59 PM

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

willett · 08-27-2013, 08:33 PM

I'll pick up a strap and a headlight switch tomorrow
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willett · 08-27-2013, 08:34 PM

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...
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mrolds88 · 08-27-2013, 08:41 PM

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

motornut · 08-27-2013, 08:54 PM

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
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MalibuSSwagon · 08-27-2013, 09:43 PM

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.

willett · 08-27-2013, 11:13 PM

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

motornut · 08-28-2013, 06:47 AM

Quote:

Originally Posted by MalibuSSwagon

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.

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
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willett · 08-28-2013, 01:13 PM

Radio heater? What the heck is that?
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mrolds88 · 08-28-2013, 02:34 PM

I think he forgot a comma.

motornut · 08-28-2013, 04:34 PM

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!
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motornut · 08-29-2013, 09:51 AM

here it is

willett · 08-29-2013, 03:15 PM

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?

motornut · 08-29-2013, 04:06 PM

Quote:

Originally Posted by willett

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?

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

jitteryguy · 08-29-2013, 06:20 PM

Quote:

Originally Posted by motornut

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

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

motornut · 08-29-2013, 10:16 PM

Quote:

Originally Posted by jitteryguy

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

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

willett · 09-04-2013, 04:12 PM

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?!?!
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motornut · 09-04-2013, 06:11 PM

Quote:

Originally Posted by willett

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

cool,small flat head from the end
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willett · 09-04-2013, 11:03 PM

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
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motornut · 09-04-2013, 11:23 PM

Quote:

Originally Posted by willett

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
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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
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willett · 09-04-2013, 11:27 PM

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
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willett · 09-05-2013, 09:12 PM

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
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08-27-2013, 05:10 PM	#1
willett Another Day, Another Dollar Join Date: Nov 2008 Location: North Vancouver, BC Posts: 1,316	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 __________________ -78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square"

08-27-2013, 06:59 PM	#3
07XCSBZ71 Registered User Join Date: Apr 2012 Location: Murphy,NC Posts: 212	Re: Wtf?? I had one doing the same thing, turned out to be a bad headlight switch.

08-27-2013, 08:33 PM	#4
willett Another Day, Another Dollar Join Date: Nov 2008 Location: North Vancouver, BC Posts: 1,316	Re: Wtf?? I'll pick up a strap and a headlight switch tomorrow Posted via Mobile Device __________________ -78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square"

08-27-2013, 08:34 PM	#5
willett Another Day, Another Dollar Join Date: Nov 2008 Location: North Vancouver, BC Posts: 1,316	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 __________________ -78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square"

08-27-2013, 08:41 PM	#6
mrolds88 Registered User Join Date: Jul 2011 Location: WV Posts: 946	Re: Wtf?? Did you maybe miss a ground that ties in at the ground "spider"? __________________ 72 GMC C2500 402/Th400 first truck (still have) 77 GMC C3500 CC dually Sold 70 C50 dump truck "Rusty" 87 K10 Suburban Sold 93 K2500 xcab 6.5TD 96 GMC K2500 Suburban 6.5 TD

08-27-2013, 08:54 PM	#7
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	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 __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350

08-27-2013, 09:43 PM	#8
MalibuSSwagon Registered User Join Date: Sep 2009 Location: Weare,NH Posts: 1,591	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. __________________ Eric 1992 Oldsmobile Custom Cruiser 1986 Chevrolet C10\|5.3L\|TKO600\|Shortbed\|Custom Deluxe 1983 Malibu Wagon\|TPI 305\|T5 5 speed\|3.73 non-posi

08-27-2013, 11:13 PM	#9
willett Another Day, Another Dollar Join Date: Nov 2008 Location: North Vancouver, BC Posts: 1,316	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. __________________ -78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square" Last edited by willett; 08-27-2013 at 11:20 PM.

08-28-2013, 01:13 PM	#11
willett Another Day, Another Dollar Join Date: Nov 2008 Location: North Vancouver, BC Posts: 1,316	Re: Wtf?? Radio heater? What the heck is that? Posted via Mobile Device __________________ -78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square"

08-28-2013, 02:34 PM	#12
mrolds88 Registered User Join Date: Jul 2011 Location: WV Posts: 946	Re: Wtf?? I think he forgot a comma. __________________ 72 GMC C2500 402/Th400 first truck (still have) 77 GMC C3500 CC dually Sold 70 C50 dump truck "Rusty" 87 K10 Suburban Sold 93 K2500 xcab 6.5TD 96 GMC K2500 Suburban 6.5 TD

08-28-2013, 04:34 PM	#13
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	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 __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350

08-29-2013, 09:51 AM	#14
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: Wtf?? here it is Attached Images __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350

08-29-2013, 03:15 PM	#15
willett Another Day, Another Dollar Join Date: Nov 2008 Location: North Vancouver, BC Posts: 1,316	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? __________________ -78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square"

09-04-2013, 04:12 PM	#19
willett Another Day, Another Dollar Join Date: Nov 2008 Location: North Vancouver, BC Posts: 1,316	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 __________________ -78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square"

09-04-2013, 11:03 PM	#21
willett Another Day, Another Dollar Join Date: Nov 2008 Location: North Vancouver, BC Posts: 1,316	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 __________________ -78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square"



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09-04-2013, 11:27 PM	#23
willett Another Day, Another Dollar Join Date: Nov 2008 Location: North Vancouver, BC Posts: 1,316	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 __________________ -78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square"

09-05-2013, 09:12 PM	#24
willett Another Day, Another Dollar Join Date: Nov 2008 Location: North Vancouver, BC Posts: 1,316	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 __________________ -78 K20 Cheyenne 454 long box, 4" lift, 35" MT's, '84 cab, '80 box "its hip to be square"

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