I have an LS in my '88 with a Hawk's harness. The only mention in their directions is connecting one wire to the blue wire on the low pressure switch which I've done. However, I don't have any power to the heater and I've got these plugs leftover from my factory harness. My engine bay was empty when I bought the car so I don't know where these go or what they do. Any help?

 

The big red wire is the battery feed to the blower motor high speed relay. The small red wire is half of the fuse holder for the underhood light.

 

Thanks for the info! I figured that one of them might be for the hood light. For the blower motor wire, what did the other end look like? There is a connector there, but did the other end go directly to the battery or was it tied into the original factory engine harness?

 

It went over to C100. If memory serves, it was 1 of 2 wires crimped into 1 connector pin.

Easiest thing to do for it now would probably be to run a similarly large wire to the starter with a high-current connector at the end to mate with what's in the pic; put a fusible link and ring terminal on it at the other end, and connect it on the batt cable terminal. Use the BIG FAT WIDE kind of terminals, not the little tiny weenie ones that are the same as the red & blue ones except to fit #10 - 12 wire. Like this one; even better if you can find insulated ones. Otherwise, if you have to use bare ones, use some insulating tubing and tape it up real good.

 

I connected that red wire to the starter for power, but still nothing. Is there a separate ground as well?

Edit* So it doesn't look like the factory ground in the harness is actually grounded anymore, so I will have to create a dedicated ground. Also, it appears that my relay may be bad as well. I've got a new one on order and will try that later this week.

 

I would discourage using those spade terminals with the colored insulators. Those only crimp the wire strands and provide no support of wire for strain relief. And the style of crimp is undesirable, leaving wide margins on the sides.

If you need a spade terminal then consider looking at the FASTON terminals with F crimp. It has wire and insulation crimp compatible with common Metri-Pack 280 uninsulated crimp tools. Overlay with one of the soft pvc boots, or use heat shrink. If you want to be a little fancier, FASTON also has a line of spade connectors compatible with hard plastic cover that look like a single plug connector.

FASTON terminals catalog

The series name designates the width of spade it connects to (250 series is 0.250 inch).

 

So I fixed my ground and determined that my relay is fine. I'm getting power to the relay (red wire) and I've confirmed continuity of the wiring going to the blower motor (purple wire). The blower will spin if independently powered, but I can't trigger the relay to fire with the interior controls. I assume that's the orange wire going into the relay (and the black is ground). Giving an additional ground to the black wire didn't do anything either. What's my next step in troubleshooting?

 

For anyone that reads this in the future, my problem ended up being a bad connection at the resistor. Either one of the pins was bent or there was some corrosion. Also for high speed, I had to ground the original plug going to the blower motor ground as well as run a new ground for the blower.