Test tool STP-6

[yam700]

Hi, I received this tool from a friend. It looks like a ball point pen but I think it is a test light of some sort. On the casing it says Snap-on STP-6. Would like to know more about it. Let me know if you need a picture.

Many thanks in advance!
Rob

[agmechjake]

I show a STP-7 in a 1973 catalog as a firing indicator for spark plugs. STP-6 is probably an earlier version

[yam700]

That is interesting, just need to figure out how to use it! Thank you for the reply, any other info would be great.

Thanks,
Rob

[agmechjake]

That is interesting, just need to figure out how to use it! Thank you for the reply, any other info would be great.

Thanks,
Rob

You hold it next to a spark plug wire and it should light up if the plug is firing. I don't know what yours look's like but that is usually how they work. Post a pic.

[yam700]

You are right! That is the coolest, I just fired up the truck and clicked the pen top and held the tip near a plug wire and it flashed in tune with the wire. I was a gm tech for 17 years and gave up the stress of flat rate to become a forklift tech. This tool will sure help with my no starts. When I find my camera I will post a pic.

Many thanks for your help for now,
Rob