Distributor wiring (aka what’s up with these wires?)

[blindbug]

So I’ve got 2 funny wires coming off my fuse box, and I THINK one is just a rigged up version of the other.

See this image for the (2) wires, yellow and pink/black.



The pink wire jumps over to this doodad above my accelerator pedal



And then the orange wire comes out of said doodad and through the firewall, which you can see in the first picture of the fuse panel:



The orange wire makes its way across the engine bay and almost to the distributor where is has been cut, stripped, and left to cause electrical fires in heaven.



Ok, now back to the fuse panel, where we get to trace this yellow wire hanging out in the WDO section of the accessory options area. It goes through the firewall straight from the fuse panel:



And then heads across the engine bay straight to the distributor, after mating up with the red wire to the left hand side of this plug:



My questions are:
1. What’s the doodad that I reference above the accelerator?
2. I THINK that the yellow wire is a rigged up replacement for the pink wire (well, orange wire) but I’m not sure.
3. Where should the orange wire be going, since it’s all cut off and junked?
4. Could any of this cause me to have a bit of trouble starting (quite a few cranks and have to lay the pedal to it, then have to give it a bunch of fuel once started or it chokes itself out)?

Thanks in advance for any advice or help you can give!

[blindbug]

Oh yeah:
1986 C10 with a 350 v8 from a 75 C20


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[bd]

So, a 75 350 in an 86 chassis.  Which transmission is in it?  The "doodad" is a detent switch.  The orange wire originally ran down and plugged into the driver side of a TH 400 automatic transmission.  The yellow > red > pink is a questionable substitute primary ignition power lead to the HEI distributor.  The HEI should receive power directly from the ignition switch via a 12-gauge pink wire (circuit #3), not the power window fuse.

[blindbug]

To be honest, I’m not sure if the transmission is the original or if it was swapped as well. It is an automatic, if that helps at all. That may explain why this truck doesn’t always kick down to a lower gear when I hit the pedal at a reasonable speed? Where would I look to know if it should’ve been connected but isn’t?

The yellow > distributor wire I would like to fix, could you direct me to where the pink wire from the ignition switch would typically travel from/to? I could find it, just want to make sure to get the right wire.


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[bd]

Refer to the factory 1986 Wiring Manual for full details.



The factory HEI feed - 3 (mm)² (12-gauge) pink, circuit #3 - occupies the firewall bulkhead connector cavity indicated above.  Note that the image is from the terminal side of the connector.  With the ignition switched on, probe the cavity using an incandescent test light clipped to a shiny bare metal ground to determine whether the circuit is viable.

To determine the transmission, compare the shape of the oil pan to Automatic Transmission Identification.

[blindbug]

You’re the man, bd. This gives me the info I need to try my hand at fixing this right! One question though, should circuit #3 be constant, during ignition, or after it’s started up? I think constant, but it’s coming from the ignition so I’m unsure. I thought that the WDO on the panel was constant.

I will take a look at the trans and report back, probably tonight.


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[bd]

...should circuit #3 be constant, during ignition, or after it’s started up?  I think constant, but it’s coming from the ignition so I’m unsure.  I thought that the WDO on the panel was constant.

With the ignition switched on, probe the cavity using an incandescent test light clipped to a shiny bare metal ground to determine whether the circuit is viable.

If the ignition feed was connected to constant power the engine would run indefinitely.  No?  You wouldn't be able to shut it off.

As wired from the factory, circuit 3 (ckt 3) is 12.6 volts with the ignition switch in the "start" and "run" positions, only.

...Could any of this cause me to have a bit of trouble starting (quite a few cranks and have to lay the pedal to it, then have to give it a bunch of fuel once started or it chokes itself out)?

With the distributor powered through the "WDO" fuse, you should expect difficult starting.  'WDO' is 12.6 volts with the ignition switch in the "run" position, only.  There is no ignition power while cranking!  You are lucky if it starts, just as you "cease" cranking.

[blindbug]

As a temporary fix, should I move the yellow wire to the right one position to the ign/acc section? Basically, is there a spot that I can move it that will emulate how it should be sending power to the distributor?


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[bd]

To determine whether reverting to the proper power source corrects the starting issue, temporarily move the yellow wire to one of the "IGN" cavities in the upper half of the fuse box.  But, don't plan on this being a long-term solution.  The distributor primary feed should rely on the slow-acting fusible link rather than a fast-acting fuse for circuit protection.

[blindbug]

Well, I was double checking, and the wire that goes to the distributor doesn’t actually go to the plug I thought it went to. It was super late and I was frustrated at some other electrical issues so I can’t tell you exactly where it leads yet.

However, I did take a picture of the transmission pan, and it looks like it is a TH350. Not sure what that means for the wire that’s supposed to go to a TH400 tranny, but here’s a picture of the pan.

[bd]

The transmission is a TH 350.

You can leave the detent switch and associated wiring alone or remove it.  It has no application beyond a TH 400 transmission.  If you decide to leave it alone, unplug the pink/black power wire from the fuse box.

If you follow the pink wire from the distributor to the bulkhead connector, I'll bet it connects as shown in the schematic diagram, posted above.

For the difficult starting complaint, check that the choke plate in the air horn of the carburetor closes completely when you initially step on the throttle with the engine dead cold.  Check the cold idle RPM on the high step of the fast idle cam, and check the ignition timing.  While you're at it, remove and inspect the spark plugs, cap, rotor and perform a tuneup.

[VileZambonie]

and order a new transmission pan while you're at it 

[bd]

A cool sand-cast pan would look really nice!