Starter relay conundrum

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Kern Dog

Build your car to handle.
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Here is a new one that I've never seen before....
It pertains to a 75 Power Wagon of mine but since the electrical systems on cars and trucks are so similar, I figure that it applies here.
(I did post this in the Truck forum as well)

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The truck is a 75 W 200 Power Wagon (1978 Grille) that was built as a 440 4 speed. I converted it to a 727 in case I needed the Wife to drive it to help me push cars around the yard.
Yesterday, it wouldn't start by the key but it would by jumping the terminals on the starter relay. It always started fine before as long as the battery was up.
Okay, bad relay, right? I went to the NAPA store and got a new one...$34! Holeeee crap. I know about inflation but jeeez! Rock auto does have them for less than half that but I wanted it now. I'm doing tree work out back and need the truck for it.
This morning, I swapped it in. Functionally, these truck relays are the same as the car relays but they have different mounting tabs on the housing.

Truck:

Relay truck.png


Car:

Relay car 1.png


Here is where it gets weird. The old relay that I took off didn't have the spade at the bottom right corner like the new ones have. The truck also has no wires going to the transmission neutral safety switch. Normally when you don't have those wires, you have to "ground" that spade on the relay to complete a circuit.

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For some strange reason, the truck has started fine for almost 7 years without the wiring or the spade to ground the circuit.
Does anyone know why? I sure don't.

I swapped in the new relay and it still wouldn't start by the key. Then I attached a temporary ground to the spade in the lower right corner and it started like normal. How did it start before all this time?

01 face 2.png
 
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Look at the original relay, generally early manual trans relays have the missing terminal actually still present but instead of having a external wire connected it connects to the case like this one...

SR6570-331744326.jpg
 
It was somehow mysteriously grounded and lost its ground I bet.
 
Look at the original relay, generally early manual trans relays have the missing terminal actually still present but instead of having a external wire connected it connects to the case like this one...

View attachment 1716205561
Yup and I "just bet" that the mounting points got dirty enough that it lost the ground. OR that little bit of solder melted.
 
Notice when I mentioned 'early" well on passenger cars that year was 69...In 70 they started using a clutch safety switch...
But your truck just by being a truck might have been enough to not get the extra safety but being a 4x4 it definitely doesn't get one, with a 4x4 when your in rough terrain guys will intentionally start the truck in gear with the clutch engaged to help get out of a "sticky" situation...
 
Wow. I’m impressed, I expected to get pages of wrong guesses!
Thank you. I went out back at 12:20 to get the relay from the truck…
A29A1F12-0C73-416F-9ADB-DC447422CEA5.jpeg


Now under better lighting and reading glasses for a better look-see…

655C6421-9190-4B87-9C73-C47534B8D905.jpeg


I now see that grounding plate.
I thought that it might have had a spade on it that broke off but it looks so cruddy, it wasn’t likely. Now looking closer, it looks untouched, maybe original?
Kooky.
Thanks again!
 
If you have the spade connector on your new relay you could run a wire to the NSS on the automatic trans (middle terminal IIRC) and gain a bit of safety. All it does is make the ground path when in Park and Neutral.

As a kid I jokingly turned the key on my sister's boyfriend's VW Bus. Imagine my surprise when it lurched forward and ALMOST hit a parked car in front of it.
 
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