Author Topic: Starting problem on 79 GMC C15  (Read 4466 times)

Offline Chase.Craddock

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Re: Starting problem on 79 GMC C15
« Reply #15 on: July 16, 2020, 01:54:32 AM »
On the solenoid, there should be two small posts horizontally from each other...do you have the starter wire hooked up correctly? Looking at it from the back, there should be a pink wire going to the post with the 'S'.
The solenoid I got only had two post on it one for the ground and one going to the battery


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Offline Chase.Craddock

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Re: Starting problem on 79 GMC C15
« Reply #16 on: July 16, 2020, 02:01:39 AM »
You could have high resistance in one or both cables. It would be hard to check resistance without a load on it. If either cable looks suspicious, corroded  or you have "repair" ends on them then replace. Make sure ground cable is attached to block or intake manifold boss. Do not attach it to an exhaust component or piggy back it to another wire.
I have a ground cable going from the battery to the Solenoid and they way the guy before me wired it is was against the header so it was burnt up a little bit, I ordered a new one, but I figured as long and it wasn’t completely ruined it would still be getting a good enough connection, then I have a ground cable that’s coming from the battery connecting to the block. Is that wired correctly?


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Offline VileZambonie

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Re: Starting problem on 79 GMC C15
« Reply #17 on: July 16, 2020, 05:21:27 AM »
 :o

Your solenoid is case grounded. You should have the Posititve B+ cable going to the solenoid as well as the fusible links. The S terminal should have the signal wire from the ignition switch Purple. Sounds like you've got something a miss
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline JohnnyPopper

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Re: Starting problem on 79 GMC C15
« Reply #18 on: July 16, 2020, 05:47:07 AM »
 :o right?

Wonder what is clicking...
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline VileZambonie

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Re: Starting problem on 79 GMC C15
« Reply #19 on: July 16, 2020, 05:56:18 AM »
Fusible links popping like popcorn?  ;D
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline JohnnyPopper

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Re: Starting problem on 79 GMC C15
« Reply #20 on: July 16, 2020, 06:00:05 AM »
Best guess  ;D
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline bd

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Re: Starting problem on 79 GMC C15
« Reply #21 on: July 16, 2020, 07:43:03 AM »
Post a pic of the starter clearly showing its connected cabling.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline mikes78k20

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Re: Starting problem on 79 GMC C15
« Reply #22 on: July 16, 2020, 12:54:57 PM »
Post a pic of the starter clearly showing its connected cabling.

I second that.
Clearly something is wrong with the way you described the connections. There should NOT be a ground connection on the starter motor itself, only the heavy gauge positive battery cable and the smaller gauge start wire....and both on the solenoid.
The ground connection should be on the alternator adjustment slotted thing and then a cable from the engine block to the frame and another from the frame or engine to the body.
No such thing as too many grounds.
« Last Edit: July 16, 2020, 12:56:50 PM by mikes78k20 »

Offline Chase.Craddock

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Re: Starting problem on 79 GMC C15
« Reply #23 on: July 16, 2020, 08:00:43 PM »


black is ground wire to battery
red is to ignition switch
when you turn the key
solenoid engages flywheel but does not turn

When I bought the truck this is how it was wired and I replaced the ground wire to the battery today


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Offline MIKE S

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Re: Starting problem on 79 GMC C15
« Reply #24 on: July 16, 2020, 08:53:08 PM »
That is a very odd looking starter. Can you give us the part number of the starter you ordered from rock auto. Also if that is the ground wire on your starter post which it shouldn’t be, were is your positive cable attached too. Although I see your using a 1998 motor so I believe that’s probably a later model starter. Possibly a gear reduction starter. To be clear does it just click or does it click and make a wirr noise without turning the engine?
« Last Edit: July 16, 2020, 09:06:08 PM by MIKE S »

Offline bd

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Re: Starting problem on 79 GMC C15
« Reply #25 on: July 16, 2020, 09:23:54 PM »


black is ground wire to battery

So, the black cable pictured connects to the negative terminal of the battery?  I concur with MIKE S.  Where is the battery's positive cable connected?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline JohnnyPopper

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Re: Starting problem on 79 GMC C15
« Reply #26 on: July 16, 2020, 09:35:45 PM »
Chase,

Please get your nomenclature right  :o

Battery 12v + positive (RED) or B+
Battery 12v - negative (GROUND-BLACK) or B-

Where is the "yellow wire" going to? It's probably the fusible link that runs the electrical system.

I forgot what year your truck is, but usually the upper 12+ is linked to the starter winding.

"how did it ever work before?"
 
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline VileZambonie

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Re: Starting problem on 79 GMC C15
« Reply #27 on: July 17, 2020, 10:46:24 AM »
I highly suggest you disconnect the battery and correct the wiring. On the B+ stud at the solenoid, you should have the POSITIVE battery cable along with your fusible links. The small stud should be live during cranking only.
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                         /  _ _ _\_
              ⌠¯¯¯¯¯'   [☼===☼]
              `()_);-;()_)--o--)_)

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