Where does the positive on the choke connect?

[hatzie]

This is where I guess the oil pressure switch is, but I don't think there are any prongs coming out of this connector or whatever this is supposed to be... I'll go out in a little while and see if I can pull that off to see what I'm working with exactly..

The switch you have looks quite different from the one called for in the parts books.  The plug for that switch is obsolete.

Get the correct AC Delco D1811 oil pressure switch and install it in place of that switch. The D1811 switch has 1/4" disconnects.

[Irish_Alley]

lol yeah sorry thats the one for the tbi motors, right hatzie?. theres another guy on here that has OPS issues and i think hes a tbi

[Irish_Alley]

hatzie whats the difference in that ac del one and PS134 from duralast?

[bd]

None of these diagrams list positive or negative..

Okay, so the dark blue, is hot, but gets grounded in the ops and turns on the choke light. The pink/white is hot and goes to the ops, then a light blue positive goes from the ops to the choke heater.

I think some of my confusion is my lack of understanding of how and what the ops actually does.. Like, how does the oil pressure switch determine the choke is on or off. Looking at the diagram, why is the dark blue turning on the choke light and not an oil pressure light?

The choke OPS is a simple normally open ON-OFF switch that responds to engine oil pressure.  Its contacts are either "open" when there is zero oil pressure, or "closed" when oil pressure rises above 3 - 7 PSI. 

Ignition power sourced directly from the CHOKE fuse (pnk/wht wire) connects to one terminal (or contact) of the OPS.  Both the dash telltale (dk blu wire) and choke heater (lt blu wire) connect to the opposite terminal (or contact) of the OPS.  The choke OPS contacts never connect to ground; the contacts are permanently isolated from ground.

The dash telltale has 12 volts of switched ignition power applied to one terminal of the bulb.  The opposite terminal of the bulb connects to the choke heater at the OPS.

When there is zero oil pressure the OPS contacts are 'open' and the dash telltale grounds through the choke heater, illuminating the telltale.  There isn't sufficient current flow through the telltale to "heat" the choke heater, so the choke is unaffected.  Once the engine is running and oil pressure builds above ~5 PSI, the OPS contacts close, connecting 12 volts to both the choke heater AND the "ground side" of the choke telltale in the dash.  With 12 volts connected to the choke heater, the choke bi-metal spring (thermostat) begins to relax and the choke plate begins to open.  At the same time, 12 volts applied to the 'ground side' of the dash telltale, balances 12 volts to both terminals of the bulb, and the telltale extinguishes. 

So the choke telltale routinely illuminates only when the ignition is switched ON and the engine isn't running.  It will also illuminate with the engine running if the CHOKE fuse blows or the OPS fails open.  It will never illuminate if the telltale is burned out, the choke heater is burned out, the choke heater is not properly grounded or is otherwise disconnected. 

Does this help sort out the confusion on circuit operation?

[m3talc0re]

This was the crap 10a fuse that was in the choke slot. I replaced it with a new 20a fuse.

[Irish_Alley]

why? the wires for the choke prob cant handle 20 amps so they will burn up before that fuse

[m3talc0re]

I think I understand you bd. So with my choke being connected directly to the pink/white + right now, with the key on, the coil is going to relax faster since it's not waiting to get power from the oil pressure building up and closing that circuit.

I wish I could get all the correct color coded wires to fix all this with XD I'll need to get a new switch and connector. And is that AC Delco D1811 the correct replacement switch?

[m3talc0re]

Digging on Google trying to find the fuse diagram shows 20a on the choke heaters... I can't seem to find one specific to my truck, though.

[hatzie]

lol yeah sorry thats the one for the tbi motors, right hatzie?. theres another guy on here that has OPS issues and i think hes a tbi
hatzie whats the difference in that ac del one and PS134 from duralast?

That's what it looks like.  The Metripack mating plug for that switch is obsolete so if it's gone it's better to just go with the 1/4" disconnect part. 
Standard Motor Products S-939  or BWD PT5590 are replacement moulded plugs with pigtail wires for the Delco D1811 and equivalent switches.  Cut the butt splices off and install with uninsulated butt splices or solder with adhesive lined heatshrink tube to cover each join.

The Duralast PS134has 1/4"NPT threads.
  The AC Delco D1811 has 1/8"NPT threads.
  The Standard Motor Products PS135 or BWD S383 or Autozone Duralast PS115 are drop in replacements for the Delco D1811 threaded in 1/8"-27 NPT...  They are all right around $10. O'Rileys sells Delco & BWD parts. I'd stick with the Delco or BWD or Standard Motor Products parts.

Digging on Google trying to find the fuse diagram shows 20a on the choke heaters... I can't seem to find one specific to my truck, though.

It'll be in the owners manual. I believe that 20A is correct for some odd reason.

[m3talc0re]

Going to Autozone, it tells me the Duralast PS115 will not fit my truck, but the PS134 is an exact fit.. Are they just wrong?

[hatzie]

Going to Autozone, it tells me the Duralast PS115 will not fit my truck, but the PS134 is an exact fit.. Are they just wrong?

O'Rileys stocks the BWD plug and the Delco and BWD switches.

The Delco switch # I quoted is equivalent to the GM part number from the 1979-1984 GM Light Truck Parts Books.

I stated specifically why the Duralast PS134 should not work on your truck.  You're welcome to go buy whatever you like.  I'd pull the existing switch and measure it with a caliper if you're worried. 
1/4-18 NPT is 0.540" effective outside diameter.  This is the thread on the PS134
1/8-27 NPT is 0.405" effective outside diameter.  This is the thread on the PS115

[m3talc0re]

My bad, I read it wrong and thought you said the 134 was the drop in replacement XD

[Stewart G Griffin]

i believe 20A fuse is correct for the choke.  It does seem a little high, but based on diagrams and the fact that i had to change one out recently, i believe it is 20amps.

[Irish_Alley]

what does the fuse box say for the choke fuse?

[m3talc0re]

I think mine just says "choke", lol