What are these wires for?

[Ardee83]

So i purchased this truck a while back, it had a 305 I put in a 350 but these wires have always been hanging from the firewall and one coming up from under the firewall around the transmission area.....ever since I owned the truck they have never been hooked up to anything..... I would like to remove them if they no longer serve a purpose I just have no idea what they go too any help as always is greatly appreciated

[Gregski]

Ardee, hate to be the dingleberry who has to ask, but tell us more about the truck, year, model, trans type, specs, etc. I know you swapped the engine, but tell us about the original machine.

[Jeramy]

wires for electronic spark control and feed back Rochester carb. my 81 also has those same wires hanging uselessly under the hood since previous owner installed a vacuum advance distributor and an edelbrock carb. or atleast im pretty sure of the second picture being that

[Ardee83]

So the original build sheet shows it was a 305 which is what I pulled out and it had a 700r4 which it still has, been replaced with a rebuild but still a 700r4. It's a 1983

So I should be able to take off the carb and electronic spark control since all that has been upgraded

[1970pelle]

From the one picture of the firewall and Dist. your holding a connector. The connector in your hand and the grommet the goes into the fire wall can be removed. Drop the glove box down and you will see a silver box sitting on top of the HVAC unit. You can remove the ESC module (electronic spark control module) and wiring harness. then pull the grommet off the harness and plug the hole left in it from the discarded wiring. Reinstall the grommet in the firewall. Then look around and you most likely will find some of the ESC harness still hanging around. Maybe still connected to relays or control boxes that are not doing anything. But cluttering up your engine compartment, get rid of the stuff.
I have done it to my last 3 square body trucks. Cleans it up nice under the hood.


Ken

[Liberty]

I think in the 83 the ESC was still above the gas pedal. In my 82 thats where its at.

[Ardee83]

Awesome on it tomorrow! Will give me something to do until the new throttle cable arrives. Any suggestions for the wire and plug coming up from under the firewall? I am going to trace it down tomorrow and see what it leads too

[Ardee83]

Ok a little more help is needed. The esc was in fact located above the glove box. I removed the connector and pulled the wires through the firewall. There are 2 wires one is pink and leads into a connection in the distributor the skinny pink one on the left hand side. The other is blue and leads into a sensor located on the passengerside just in front of the starter. Before I completely remove them I wanted to make sure they are no longer needed...... I am tracing the connection coming from under the firewall now

[Jeramy]

one down by starter is knock sensor

[Ardee83]

Can it be removed?

[Liberty]

Try starting the truck without them, if it runs you are good to go.

Here is a pic I found involving wiring going to the HEI dist.

[Ardee83]

Awesome diagram! Thank you! Next question is for the wires that are coming from under the firewall..... the lead into the transmission I tried my best to take a picture. I have had the truck for 2 years and when I made this post found out they were not connected to anything..... can they be removed or where do they need to be connected if they do?

[Ardee83]

For the above post a little more information. It would be the connection that leads into the transmission as shown in red. If they can be removed I will remove them, if they need to be hooked up, I need to know where they go.

[Liberty]

I think that needs to be on something to activate the lockup.

[Ardee83]

So i would like to hook this wire back up, can anyone tell me where it is supposed to connect?

[Ardee83]

Anyone still have the stock wiring ran on their ride that they can show me where this is supposed to connect too from the transmission? I may no longer have the connection I can't seem to find it

[Liberty]

I'll check and see if my TH350 has the same wire or not.

[bnoon]

There should be a two wire switch/solenoid on the firewall with a vacuum hose going to it. Second picture circled in yellow in the first post of this thread. http://67-72chevytrucks.com/vboard/s...d.php?t=227308

[bnoon]

BTW, if you don't have one of those, all you do is buy one from a salvage yard (or Summit Racing) and hook it up. Cheap compared to the gasoline you're spending not having lockup on the highway.

[Ardee83]

Awesome! Thank you for that post. The truck no longer has that and it makes sense as to where it would go since it was just setting inside the plastic sleeve against the firewall. I will pick one up and get it installed correctly. Thankfully I rarely drive in OD but it will be nice to have when I do. Thanks for everyone's help as always

[Ardee83]

So to continue with the lock up wire not being connected.... when I am driving in OD the transmission seems to slip and the rpms will jump and the fall right back where they were. This happens very quickly. After reading some of the other forum posts with people having the same issues, they were advised to unplug the lock up wire. Could mine be slipping because its not hooked up? What could be causing it to slip?

[bnoon]

Originally Posted by Ardee83

So to continue with the lock up wire not being connected.... when I am driving in OD the transmission seems to slip and the rpms will jump and the fall right back where they were. This happens very quickly. After reading some of the other forum posts with people having the same issues, they were advised to unplug the lock up wire. Could mine be slipping because its not hooked up? What could be causing it to slip?

No, the transmission will simply be in 4th gear without lockup. It will not cause any other issues. You can test to make sure you're getting voltage to the solenoid, and run your ground wire to a temporary switch (or just hold the ground wire to ground while driving to lock it, then unground it when you slow down to unlock it). That way at least you know it works before you spend money on a new vacuum lockup switch.