What is this?

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Mar 4, 2014
This box is under my dash on my 1971 FJ 40.
It's next to the signal flasher
I googled the part number and it came up as a speed marker. I went to some web sites they state the speed marker is in the speedo cable.
I'm lost with this thing and what it does. It's not on any wiring diagrams.
ImageUploadedByIH8MUD Forum1419089118.719672.jpg
Checked the fische. It is a speed marker relay, not the speed detector. I think they were combined in later years. So the detector must have a switch that controls this relay to illuminate a maintenance light (if it works the way the later speed markers/detectors did). If there is another purpose, I don't know it.

Is there some sort of EGR or maintenance light on that vintage truck? I don't know where it is exactly, but the fische indicates that there is an EGR light for that vintage. Just out of curiosity, is that a California truck (original destination)?
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My brother bought the truck new in NJ. So it's not a Cali truck.
There's no check engine light or EGR light. I guess the speed marker connects to the sensor in line with the speedo cable. There's not much on this stuff in the manuals I have.
Thanks for your reply

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