Emergency Drive Light ... ?

[Fast79Chief]

Got an issue with my Emergency Drive dash light being lit all the time. This may be normal or a sign of something wrong? When the selector inside the glove box is in the OFF position, the light is clearly lit. When in the ON position the light is much brighter. Is this normal?
I have a 79 Chief with Quadratrac.
Thanks.

[mx71]

This isn't normal. It shouldn't be on when you aren't locked.

[Fast79Chief]

So If thats the case, I'm wondering if the light activation switch on the transfer case is partially engaged enough to make contact? Is there a way to verify that my Emergency Drive is totally OFF when the vehicle is running down the road?
Thanks

[toothofwar]

Check the wiring from the top side of the quadratrac case up to the main harness. The light gets its ground from the case when the switch in the case is activated. (Locked in e-drive). If the wire has a nick in it, it could be partially grounded giving a dull glow. When you engage the e drive, it gets the full ground path and glows bright. You could also disconnect the wire at the case and see if the light is still glowing. If so, then the wire is grounded and needs further troubleshooting.

Sent from my SAMSUNG-SM-G891A using Tapatalk

[Fast79Chief]

Good info tooth!
I'll try that. I still would like to know if there is a way of testing a 79 Chief to see if the Emergency Drive actually engages and disengages.
I do have 4 jackstands if that would enter into it?
Just dont full understand just what it does mechanically when you flick the vacuum switch in the glovebox, and if it can be tested up on a lift?
Thanks.

[Cecil14]

There is a procedure in the TSM for testing the differential in the case, it uses a torque bias between the front and rear outputs. In e-drive, these should be locked together (spin the same speed, always). In normal operation they can spin different speeds. Disconnect one driveshaft (chocks, parking brake, etc.) and try to turn that output. You'll have to look up the torque spec, you may need someone standing on the brakes to create enough resistance.


aa

[mx71]

You can lock it then drive in tight circles on a dry road. It'll have a problem doing that if it's locked.

[Fast79Chief]

You can lock it then drive in tight circles on a dry road. It'll have a problem doing that if it's locked.

Thanks 71. If I do this on dry blacktop, will it damage the unit in any way? Of course I'll take it very easy, but it sounds like it will very noticable between locked and open?
I just want to make sure, even if I cant get the dash light to go out, that the unit is NOT engaged when the dial is in the OFF position.
Thanks again.

[Fast79Chief]

If anybody knows the answer to this question, let me know please. I seem to recall reading a very old article about the mid-70's Quadratrac, and it actually stated the percentages of drive force that this transfer case sent to front and rear axles. It stated the 'bias' when locked and open. Is it true that my 79 Chief when in the OPEN position is still getting like 35 percent power to the front axle?
If anyone has info on this old article or one like it, please share the source with us.
Thanks a lot.