Littlefuse 3961573
 

Hello. I'm rebuilding my 1970 C10 short bed. I got tired of doing body work, so I switched it up and started working on my wiring. (idiot lights, to gauge package, repair cracked and cut wires, ect. I should say that Its a AC truck, however I took the AC out long ago.
On the wiring harness that goes to the starter, dist, and temp and oil pressure, the po had two wiring harness's jerry rigged together. On the firewall was what I think was a relay. Its marked Littlefuse Inc, and numbered 3961573.
To make a long story short, while trimming that double harness of stuff I thought I didn't need, I now can't find where that connector goes to the mystery relay. (Wires green and blue I think) I guess my question is, was that relay for the air conditioning? Do I need it now? I've used search, looked at all of the diagrams, and read all of the threads, but cant find the answer. Can anyone help?
I don't know if this was clear or not. I hope so.

Re: Littlefuse 3961573
 

A Google search of Littlefuse 3961573 comes up with numerous hits indicating that it is a TCS relay.

TCS (Transmission Controlled Spark) is an early emissions system that was introduced around 1970 and doesn't show up on a lot of the wiring diagrams. In addition to the relay, the TCS system originally had a 2nd temperature switch on the engine, a switch on the transmission, and a solenoid valve plumbed inline with the vacuum hose going to the distributor advance.

Unless you have local emissions inspections that require you to have all that stuff hooked up, you can delete all the TCS parts and their associated wiring.

Re: Littlefuse 3961573
 

Thanks, I googled it as well, even went to the little fuse web site. I saw something about transmissions, and figured I didn't need it, but then one of the things I read was talking about regulating temperature. I was unsure after that. Never did like thing cluttering my firewall. I can't even be sure those wires were attached to anything. That wiring harness was a mess. It ran great though, so, who knows?