TAND 'M LOCK light help!..

[1966chevroletpu]

I just wanted to know what this light on my instrument panal (TAND'M LOCK light) was for, the thing is when i first bought the truck the light never went on, until one year later. now the light is on, and its been on ever since...can anyone help me wit this...thanx

[LILRED66]

This should not be on. Check behind the dash cluster to make sure you haven't plugged the light socket into the wrong location.

The tandem lock light is functional on the big bolt (C50/C60/C80) trucks with tanden rear axles, so your C10 shouldn't have this light coming on.

[1966chevroletpu]

thanx i must of plugged a bulb into that hole then...thanx for the help.

[66trkbldr]

do they all have this, or just the tandem trucks, one of my trucks has this{with gauges} and one doesnt{idoit light},both c 10. just thought that maybe somebody swapped it out!

[kris's66lwb]

they should cuz the guage clusters didnt change from the c10 of the c80 they just hooked up different lights i thinks correct me if i am wrong

[LILRED66]

I believe the warning light dash did not have the tandem lock and the gauge dash did have the tandem lock. I believe that is because the big bolts had the gauge cluster.

[63 & 64 Bowties]

I don't have any info on why a C-10 would have a tandem lock light, but I can tell you for sure what a tandem lock is, if that helps. Being a 60 year old ex-truck driver, I'm very familiar with tandem lock.
It would only be in tandem trucks (3 axles.) In normal driving conditions, only the front tandem drives (2nd axle of 3) When you throw a switch labeled "power divider" it engages the power divider in the rear axle (3rd axle of 3) and engages the driveshaft between the two rears (sorta like lock-out hubs on a 4x4) and both rears (#2 & #3) now drive (pull.) It's used in mud, or on snow/ice. The warning light is on the dash because, just like 4x4,'s you don't want to drive on dry pavement with the tandem lock engaged.
Hope that helps.

[1966chevroletpu]

yup i think thats it 63 & 64 bowtie, thanx for the info. Ive always wanted to know what that was, an thanks for your help again LILRED 66..

[factorystock]

Tandem conventional models were known as M 60 and M 80. This M 80 had the 34,000 lb rear ends with the tandem lock feature.It shared the same dashboard with pickups, but had a lot more gauges. M 80's came with the big 409 V8 5 speed with 3 speed auxilary transmissions and air brakes for dump truck service.

[63 & 64 Bowties]

Boy, you couldn't drive that thing on the road these days. Not like that. No sideboards, no tarp, and the load spilling over the sides.

[LILRED66]

Man, that is a cool rig. I need one like that for my commercial general contracting business. What a nice attention-getter.

[jchav62]

On my 62 I have a gauge cluster from a 63 big truck. It has gauges instead of idiot lights and it has a 'Tandem Lock' light and an 'Over Speed' light. When my right blinker is on, the tandem lock light blinks, and when the charge light comes on it says overspeed...or vice versa...

[LILRED66]

jchav62:

Look behind the cluster, to make sure the right blinker light socket is in the correct hole. It appears you have it installed in the Tandem Lock hole, instead of the blinker. Also, the blinker and Tandem Lock holes will have a cardboard tube from the socket hole in the back bezel to the front bezel. Sometime these fall out of place and allow the light to bleed over from the adjacent light socket hole. Try the same thing with the overspeed socket hole. I hope this helps you get your holes/sockets/cardboard tubes straight.

[63 & 64 Bowties]

Originally Posted by LILRED66

Man, that is a cool rig. I need one like that for my commercial general contracting business. What a nice attention-getter.

Here ya go:
63 D60 dump truck on ebay
or
61 GMC dump on ebay

[LILRED66]

63 & 64 Bowties:

Thanks for the links. Both look like decent rigs. The '63 is actually a '64, according to the windshield, dash, body badges and VIN. It has a factory tach, also.