Patro46

Last wiring issue in my LS swap. The swap is taking place in a 1974 Corvette. The pcm has two large 10 gauge wires leading from it. One of them connects to the starter's "S" terminal. (Solenoid)

The other one is the same 10 gauge size, purple in color and leads to a single round extension, though I don't have the extension nor do I know where it goes (or went).

First issue. The 74 Corvette has all starter control wiring as well as factory wired for the neutral safety switch. This said, I've been told I needed to connect the purple wire with the ring terminal to the starter solenoid. Why is this required if I already have a starter system intact operating off the ignition switch? I don't have a problem hooking it up, but it doesn't operate off my factory ignition switch so it leaves me a tad confused as to why it's needed.

My son had a 99 Camaro SS, and the second wire in question leads up from the passenger side, is a purple 10 gauge factory wire, and heads toward the radiator support. Is this the power lead for the fans?

THANKS!

noskcaj

iTrader: (2)

I think this should be in the electrical section, but it depends on if the pcm is a 98 or a 99+. Here's a link to the pinouts for either pcm -

http://www.norotors.com/index.php?topic=3164.0

The pcm will have two different connectors, one of them has a red connector and the other is blue, I think the pcm is labeled on one side as well. Trace the wire back to the connector and it should have a little number next to it.

As far as the starter solenoid, I did a swap into a 240sx and I did not use the pcm for starter solenoid, just wired as Nissan had and works great.

gagliano7

You can just use your starter wires from your vette. That is what I did with my 5.3 in my 1992 chevy pickup. That purple wire is for the starter from the original car that the ls1 came from.

JakeFusion

iTrader: (7)

Moved to the conversion section.

lsxRanger94

Correct.

74modified

I used the Corvette wiring for my the starter on my 74.
Just remember that the 74 was the last year for points ignition, and the original starter wiring is a lot different than later model cars. It has voltage coming back from the starter to the original coil.

lsxRanger94

Wasn't 74 a crossover year for HEI?
The points wire is one you eliminate out of original harness as a LS engine only has 1 small post on the starter solenoid.

74modified

Maybe I need to clarify. I have a 74 Corvette that I swapped in an LS. The stock 74 has a points, mechanical tach drive distributor. 1975 started using HEI. There are two (2) power wires going to the original coil. One for power in "start" and one for power in "run". This sometimes gets people confused trying to use the original ignition wiring to power the ECM. They end up with no power depending on ignition switch position.
http://img.docstoccdn.com/thumb/orig/122040706.png

lsxRanger94

I looked it up. GM put HEI in mid 1974 model year. So build date may of 1974 and later. You may have an earlier build date or GM is wrong.

74modified

The OP said he has a 1974 Corvette. What you are not realizing is the CORVETTE, not a Camaro or Impalla or other GM had a mechanical tachometer. It wasn't as easy as just changing the engine wiring harness. They had to change to a different tach and dash harness as well. It changed in the Corvette in 1975. But really it only matters to the OP as you are not working on a 74 C3 are you?
http://www.vettefacts.com/C3/1975.aspx

http://en.wikipedia.org/wiki/Chevrol...vette_%28C3%29

http://www.corvette-c3.eu/php/techni...orvette-c3.php

http://www.harchelroadmotors.com/C3Corvette

http://www.musclecarclub.com/musclec...istory-3.shtml