rear defrost...

Ok, I'm chasing down a problem somewhere, but haven't gotten there yet. Rear defrost isn't working.

93 S10 Blazer

Got power to plug in rear at tailgate just before Driver side plug. Power to hatch strut plug. Power to bottom of strut. Power to top of strut without defrost window wire plugged in. When I plug it in at the window at top of Driver side strut, it goes dead. If I leave it unplugged, power. Went to other side, passenger side to check plugs there. No power yet. I cleaned the ground on that side. Pulled the plug out of the body hole and tried checking, but nothing. I did have power there the other night so, not sure what I did. I'm trying to check both sides of the window to make sure it has power. But what does it mean when you unhook something and it has power, then hook it and it has none? Is there a short somehwere or ?

Any ideas.
Thank you.

It is more or less not enough power.
Does the indicator light come on or stay on or go out when you plug them in?
The rear defogger is controled by a rear defogger timer relay located on right of brake pedal support bracket.
Check for good power to it and power out of it to rear defogger.
Good luck

It is more or less not enough power.
Does the indicator light come on or stay on or go out when you plug them in?
The rear defogger is controled by a rear defogger timer relay located on right of brake pedal support bracket.
Check for good power to it and power out of it to rear defogger.
Good luck

Thanks MT. The indicator light on the side of the dash works and goes on normally and stays on for the period of time it is timed for. Just not getting anything at the rear window. This is when I get power to the driver side of the plug/wire rear window. When the timer runs out, no power, but that's normal I think. Shouldn't be any power to it if not calling for it? Plugging in and unplugging doesn't affect the defog switch any. it just runs it's normal timer period then shuts off.

If the defog relay is bad, would it still get power to the back plug? Test light was about half lit, not full as if you connected to both sides of the battery. Weak signal. Could it be that?

Yes - you have a poor connection between defog relay and your test point- look for a connector that is corroded, a frayed or thinned out wire- that is only holding on by a thread- you are able to show voltage- but not pull any type of amps- classic poor connection, burnt contacts, typ of scenario..