Tandem Lock Light
 

So my '71 C10 has a heavy truck cluster in it with the Tandem Lock Light. Yesterday that light came on and has remained on since. Out of curiosity any ideas as to what would be causing that light to come on?

Re: Tandem Lock Light
 

Stomp on your brake pedal really hard. The light will go out.

Re: Tandem Lock Light
 

Scott I thought that was how to re-center the shuttle valve (to extinguish the brake light that had tripped) once the leak that caused the pressure differential between front and rear systems had been repaired? I thought the tandem lock light had no purpose when a medium duty cluster was installed in a light duty truck?

Re: Tandem Lock Light
 

As far as I know there is no purpose for that light in a light duty truck. Just curious as to what would activate it all of the sudden. I'll dig a bit tomorrow.

Re: Tandem Lock Light
 

He has a heavy cluster in a c10...it IS the brake light that is coming on ;). The tandem lock is in the same spot in a heavy cluster that the brake light is in the 1/2 ton cluster.

Re: Tandem Lock Light
 

Check to see if all of a sudden your truck now has an extra axle on the back end of it.

Seriously though, I never knew our smaller trucks used the same lenses that the big trucks have, unless it was just some kind of fluke. But what may really has happened is that someone might have install a dash cluster from a big truck. I would love to see a picture of that.

Edit: leddzepp, looks like we were both responding at the same time.

Re: Tandem Lock Light
 

Ahhhhh, touché.

Re: Tandem Lock Light
 

The cluster is out of a medium duty truck as it has the tandem lock light and an overspeed light. Without these illuminated it looks just like any other light duty cluster. I didn't realize it was a medium duty cluster until I pulled it and was replacing bulbs.

I don't have a good picture of it now, but can post one in the AM.

Re: Tandem Lock Light
 

Of course after being on for 3 days straight, the light is out this am. If you look close at the 7-8 o'clock range of the fuel gauge you can faintly see where the light is located.

http://i66.photobucket.com/albums/h2...pslzcigzip.jpg

Re: Tandem Lock Light
 

Thanks for the picture. I'll have to check on my Cluster. I took one out of a 2-Ton for the Vacuum Gauge.

I like the Tach by the way.

Re: Tandem Lock Light
 

I'm searching for an Air Pressure gauge (not vacuum, but air system pressure) if anyone sees or has one in these clusters!

Re: Tandem Lock Light
 

That's what I was looking for myself, an Air Pressure Gauge in some local junk yards, but decided to grab the Vacuum Gauge while I was at it.

Re: Tandem Lock Light
 

No problem and thanks!