Unknown wires

[Mitch2372]

I have a 1985 GMC K1500 with a 305.   In the process of pulling the engine, I thought that I had labelled all vacuum lines and wiring harnesses.   However, after pulling the engine and starting to clean up the engine compartment, I discovered two wires that are not labelled.   They both come from the driver's side firewall and are long enough to reach the passenger side.  The first wire is pink with a black stripe.  The second is solid green.  I have attached pictures of each.  Any help would be greatly appreciated.

[VileZambonie]

Engine coolant temp sending unit and electric choke

[LTZ C20]

Green is for coolant, pink for choke.

[Mitch2372]

Thank you for the replies.  I have attached the pictures of my actual choke and the corresponding pigtail.  I have also attached one of what I think is the temp sensor in the t-stat housing.  It has an oval connector with two pins inside. 

[Mitch2372]

Ok, I think the green is for the engine temperature switch that goes to the factory gauge.  I forgot I bypassed that with an aftermarket  gauge.  I think the original switch went in the drivers side block and looked like this attached picture.

[LTZ C20]

Your choke and connector look to be correct. Those two go together.

The green wire goes with the type of sensor you posted in reply #5.

The one you pictured in the intake manifold is a temp sensor yes, but it is for later models with an ecm far as I know, it's the type my TBI engine uses. Do I understand you correctly that you used this newer style sensor  for an aftermarket temp gauge?

[Mitch2372]

Hey LTZ, thank you for your reply.   The sensor in the tstat housing is actually OEM, I just need to find the corresponding pigtail.  My truck has the 5 pin module, so it is not quite computer controlled.  I replaced the original temp switch from the drivers side head with an aftermarket gauge, not the sensor in the tstat housing.  Any ideas on the pink/black wire?

[LTZ C20]

Oh ok, I got it now.

Wait a second, didn't Vile say the pink wire was for the choke originally? I think there was a mix up some where. We have 3 wires here that are in question:

1- A green wire with a white plastic connector. That has been found to belong to temp sensor in drivers side cylinder head.

2 - A pink wire with black stripe and a black plastic connector. That WAS stated to belong to the choke. Here's the problem:

3- What looks to be a green or blue wire with a grey plastic connector and a piece of tape that you say has been labeled already as the choke wire.

So now we have to determine which wire is actually correct. So seeing as how the engine is out of the vehicle, it will be easier to do the following:

Using a small flat blade screw driver, in fact it needs to be pretty small or a small pick tool, depress the locking tab inside both the pink/black wire and the wire with the tape on it. The locking tab is a small piece of metal that is built into the back side of the metal terminal INSIDE the connector. It should be accessible from either the front or back of the connector. Once you see it, all you have to do is push the screw driver or pick tool at it and it should bend down and the plastic connector should slide off of both wires.

Now, take the plastic connectors you removed over to the carburetor and see which one actually fits properly and matches the shape of the plug on the electric choke.

Once you have that figured out, label the correct wire as needed, bend the locking tab back up on the metal terminals and reinstall the plastic connectors on each wires, most times they make a small click noise when seated, if they don't click it's ok, as long as they won't pull back off with a gentle yank.

Now we need to consult the wiring diagrams for your truck to figure out where the other wire goes.

[Mitch2372]

The inside of the pink wire connector has a male spade terminal.   The choke also has a male spade terminal, so I don't think that  will work.   The blue wire labeled choke is a female that pairs pretty well with the male connector on the choke. 

[LTZ C20]

Ok, I looked up your truck, in the 1985 Chevy/GMC wiring manual, V8 engine with federal emissions (that may or may not be important,  pretty sure it's not). On page 9, smack dab in the middle of the page, above the words V8 engine, federal emissions, RPO  blah blah blah. There is a group of wires and sensors, they are labeled with a circuit number and color.

1- LIGHT BLUE wire, circuit 78, CHOKE HEATER.

2- PINK/BLACK wire, circuit 39, CARB FUEL SOLENOID or CARB ACCELL PUMP FUEL SOLENOID.

Now I haven't had to work on a electro q-jet really, so not sure which, it appears in the diagram that that the pink/black wire comes FROM the Carb Fuel Sol  and goes TO the Carb Accell Pump Fuel Sol. So there should be another plug some where, my guess is near the carb, on top of the engine, that matches the shape of the black plastic connector that's on the end of the pink/black wire.

The diagrams are kinda small to read on my phone, the circuit numbers might be wrong (not super important) what is important is the wire colors.

The diagram can be found in the technical pages, 1973-87(91) GM Pickup Manuals, edited by Irish_Alley, scroll down to Wiring Manuals, scroll down to 1985 Chevy, click and open, go to page 9, observe wiring for visual assurance.

[Mitch2372]

I probably should have stated this earlier, but it has an aftermarket carb that the previous owner installed (see pic).   Maybe this explains why there is no corresponding connection for the pink wire?

[LTZ C20]

Well then.... that does put a bit of a damper on the situation. Is that an Edelbrock replacement for the original q-jet? That's what it looks like.

[Mitch2372]

I believe that it is supposed to be an Edelbrock replacement. 

[LTZ C20]

Then the Carb Fuel Sol/Carb Accell Pump Fuel Sol theory should still apply.

[Mitch2372]

It's an Edelbrock replacement but I don't believe it is an exact replacement.  I believe there was a sensor on the passenger side front of the OEM carb that is not present on the Edelbrock.   So is this pigtail not used now?