Author Topic: Wiring 101  (Read 3151 times)

Offline bd

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Re: Wiring 101
« Reply #15 on: August 02, 2020, 10:46:13 PM »
Regarding the choke, read through GM electric choke operation.  The choke OPS should have two prongs and three wires, pnk/wht (ckt 350, choke power from the CHOKE fuse), lt blu (ckt 78, choke heater element), and dk blu (ckt 931, instrument cluster choke indicator lamp).  I don't have a factory diagram of the 1989 choke circuit that definitively shows which bulkhead connector cavities serve which wires.

See the two images below for the engine oil pressure gauge wiring.  The gauge OPS has one prong with a single tan wire (ckt 31).
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 kjnmontana

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Re: Wiring 101
« Reply #16 on: August 03, 2020, 09:04:43 AM »
So, the three wires off the bulkhead circuits going to the two prongs on the choke OPS (does it matter how they are paired?). How does the choke wire tie in with the choke OPS?
KJ

Offline bd

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Re: Wiring 101
« Reply #17 on: August 03, 2020, 09:27:58 AM »
Did you study the article (GM electric choke operation) previously linked?  The two blue wires share one terminal of the choke OPS, the pink w/white stripe wire connects to the remaining terminal of the choke OPS. 

Only two wires route to the bulkhead pass-through connector - pink w/white stripe and dark blue.  The light blue wire connects to the choke heater element on the carburetor.
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 kjnmontana

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Re: Wiring 101
« Reply #18 on: August 03, 2020, 11:28:35 AM »
I did study the GM electric choke operation diagram and noted that the light blue wire connected the choke heater to the choke OPS.

What is confusing is that you stated the light blue wire is associated with circuit 78 as well as being used to connect the choke heater to the choke OPS.

As it stands, I have the two blue wires (circuits 78 and 931) coming off the bulkhead pass through connector as well as the pink/white coming off circuit 350. These will be connected to the two prong choke OPS as you described.

According to GM choke operation diagram, the light blue wire is then used to connect the choke heater and the choke OPS which makes it seem like the choke OPS has a forth wire being connected to it.

You also said “Only two wires route to the bulkhead pass-through connector - pink w/white stripe and dark blue.  The light blue wire connects to the choke heater element on the carburetor.”  I clearly have the light blue wire coming out of the bulkhead pass through connector as well so I’m struggling with the light blue wire’s routing.
KJ

Offline bd

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Re: Wiring 101
« Reply #19 on: August 03, 2020, 01:55:57 PM »
Perhaps there is more to the story for 1989 models.  I did not find a wiring diagram that illustrates the 1989-specific choke heater circuit.  Where does the wire that connects to the choke heater run?  Did you trace it?
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 kjnmontana

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Re: Wiring 101
« Reply #20 on: August 03, 2020, 02:07:06 PM »
That’s the problem, the electric choke heater wire wasn’t connected when I dove into the wire cleanup and the choke OPS connector was fried and hanging off the OPS sender fitting making it darn near impossible to see how it was configured...
KJ

Offline bd

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Re: Wiring 101
« Reply #21 on: August 03, 2020, 03:39:23 PM »
So use a test light and meter to decipher what those wires do.  Keep a cool head, apply some logic and before you know it, you'll have your answers.  Determine which wire illuminates the instrument cluster choke lamp when grounded, which has ignition power, where the "extra" blue wire goes inside the cab, and why.  It shouldn't be too difficult to sort out.
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 kjnmontana

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Re: Wiring 101
« Reply #22 on: August 03, 2020, 04:23:55 PM »
Unfortunately the instrument cluster is pulled from the dash as is the majority of the cab’s wiring so circuit continuity checks are limited. I was able to see the other side of the bulkhead pass through connector and saw only the dark blue wire exiting the 78/931 circuit slot and terminating at the instrument cluster loom connector leading me to believe it is the circuit 931 choke indicator lamp source. Not sure what the other wire does/did, but I can now complete the the choke OPS and choke heater connections. Thanks
KJ