Author Topic: 1975 c-10 truck problems  (Read 7884 times)

Offline Slooby

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1975 c-10 truck problems
« on: February 25, 2011, 05:02:21 pm »
Alright I'm unsure of the problem but headlights are on when truck's ignition switch is off and truck stays running, started today and has got me stumped.

Offline beastie_3

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Re: 1975 c-10 truck problems
« Reply #1 on: February 25, 2011, 05:31:55 pm »
duh, pull the headlight switch to turn off the truck!

1. check grounds
2. check ignition cylinder

Offline slammed79

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Re: 1975 c-10 truck problems
« Reply #2 on: February 25, 2011, 06:46:29 pm »
But the headlight switch is on a constant hot circuit, so they will remain on when the truck is off.
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Offline beastie_3

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Re: 1975 c-10 truck problems
« Reply #3 on: February 25, 2011, 07:36:43 pm »
I was being funny.

Offline Slooby

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Re: 1975 c-10 truck problems
« Reply #4 on: February 25, 2011, 07:48:03 pm »
The headlight only come on no taillights, but the radio and all will shut off while the motor stays running when you turn the ignition switch off, all grounds are good.  I know because I have been working electrical bugs on this truck for a while.  Has new ignition module so I don't think it went bad but I have had faulted new parts quite often. 

Offline VileZambonie

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Re: 1975 c-10 truck problems
« Reply #5 on: February 25, 2011, 07:54:57 pm »
Unplug the Alternator Field terminal and see what happens.
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline txchainsawgogi

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Re: 1975 c-10 truck problems
« Reply #6 on: February 25, 2011, 09:51:00 pm »
duh, pull the headlight switch to turn off the truck!

1. check grounds
2. check ignition cylinder
'


wouldnt pushing it IN turn the truck off?

Offline beastie_3

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Re: 1975 c-10 truck problems
« Reply #7 on: February 26, 2011, 12:07:41 am »
duh, pull the headlight switch to turn off the truck!

1. check grounds
2. check ignition cylinder
'


wouldnt pushing it IN turn the truck off?

I thought the headlights were the problem....:)

Offline Slooby

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Re: 1975 c-10 truck problems
« Reply #8 on: February 26, 2011, 11:47:01 am »
Unhooked the feild terminal on the truck and nothing happened.  No change at all.

Offline VileZambonie

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Re: 1975 c-10 truck problems
« Reply #9 on: February 26, 2011, 01:39:34 pm »
How are you shutting the truck off? Unpugging the coil? Do the healights shut off when you do shut it off?
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              ⌠ŻŻŻŻŻ'   [☼===☼]
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline Slooby

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Re: 1975 c-10 truck problems
« Reply #10 on: February 26, 2011, 01:49:55 pm »
Stalling it out being as it's a manual, yes headlights stay on and if you hit the blinker it comes on as well.  Right now I'm a lost for where to start other than pulling the whole dang wiring harness out and rewiring it from scratch.

Offline slammed79

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Re: 1975 c-10 truck problems
« Reply #11 on: February 27, 2011, 01:09:00 am »
I re-did the wiring in my 74 in about a weekend. I found an unbutchered harness at the junkyard and went to town. Still gotta hook my dome light and courtesy lights up though, I've been meaning to get to that for over a year now.
74 C10 Long bed 350/SM465 Lowered on 20's

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Offline roger97338

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Re: 1975 c-10 truck problems
« Reply #12 on: February 27, 2011, 02:17:29 am »
Have you tried, you know, jiggling the light switch? Start with the easy stuff.

Offline VileZambonie

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Re: 1975 c-10 truck problems
« Reply #13 on: February 27, 2011, 11:36:57 am »
Stalling it out being as it's a manual, yes headlights stay on and if you hit the blinker it comes on as well.  Right now I'm a lost for where to start other than pulling the whole dang wiring harness out and rewiring it from scratch.

So your headlights are always on or only on with the ignition switch on? What comes on if you hit the blinker?

You obviously have a short to voltage but if you can be as clear as possible with the details it would be more helpful.
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline Slooby

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Re: 1975 c-10 truck problems
« Reply #14 on: February 28, 2011, 06:03:42 pm »
I figured out what the blinkers where from, I forgot I pulled the flasher relay.  But I'll have to check to see if the headlights are on when the ignition is on, but it's never been like that before, but when the ignition is off the headlights do stay on.  I'm wondering if it has anything to do with the problem I had back about a month ago when it had an existing push button start someone installed because they where to lazy/cheap to purchase a new clutch safety switch.  They crossed the wires and finally grounded out frying the starter solenoid and the battery.  I didn't think to check it because I figured he might have new what he was doing and I didn't have any issues until that day.  So I ripped it out, traced, and pulled the added wires being as he just added new wire to the battery and starter.  I'll probably start on it this weekend agian or just wait being as I go out for a few weeks due to the military and just start tearing it down and get a new/updated harness to rid the glass fuse box.  I plan to start getting the frame ready for bagging it.