Over speed warning light

[Tripmiester]

Hey guys

Anyone know how the overspeed warning light is activated on the mechanical side?

I am installing my cluster, and I have the light socket on the cluster wiring harness, Along with the speed warning tube. The wires go to the engine harness not sure what it supposed to do in the engine bay. Any help would be great. Thanks guys.

[ray_mcavoy]

I believe the over speed light was only functional in the medium duty trucks with engine governors. It was activated by a vacuum switch on the distributor.

The light is present in all of the gauge type clusters and was simply left unused in the 10-30 series trucks and other applications that didn't have an engine governor. These clusters also have provisions for a tandem lock light that was only made functional as needed in the larger tandem axle trucks.

Some amount of wiring may be present (especially if you're converting from warning lights) because the over speed light circuit uses the same wiring that was otherwise used by the oil pressure light on the warning light clusters.

[Tripmiester]

Ok thanks for that info! I see those 2 and I will block them off with a piece of duct tape, how about the other hole opposite the tach light socket. Was that for a vacuum gauge? I am not using one, so tape it off as well?

Thanks
Steve

[ray_mcavoy]

You're welcome! Yes, that hole opposite the tach light was used for an optional vacuum gauge so you can tape that one off as well.

[AcampoDave]

You can use the overspeed light for a "dummy" light. Easy to do with a tee and a sender for the oil pressure or even a second temp sensor made for a light. I've even seen a thread where someone made and emergency brake indicator with it.