wait to start light not lighting

[RLDSL]

The wait to start light on my '92 f350 won't light up.
I put 12 volts to the wire at the controller end and the dash light came on.
I've replaced the glow plug controler glow plugs. checked wires to glow plugs, all good, cleaned ground connection for glow plug controller and put back on with conductive grease, .
Glow plugs working fine, They come on when cold and cycle at times appropriate for temp.Truck starts great. just no light.
Any ideas?
Thanks----------Robert

 

[MIDNIGHT RIDER]

If your truck is like my 85, the glow plug indicator light gets its power from the cold side of the glow-plug relay that is on the right fender-well. If your plugs are working, the cold side of the relay should have power when they cycle, thus sending power to the light.

Put a jumper to the indicator wire at the relay and see what happens. Of course, unhook it from the relay first, or you will also be powering the plugs.

These indicator lights must be pretty much bullet-proof cause mine has been working for some 20 years.