gday, got a 93 EB XR8, yesterday jumped in and my power windows wouldn't work, checked the circuit breaker, that was ok, I find I also had no Rear Demist, no power mirrors, no heater fan and no wipers.
I checked for 12v at the demist and accesory relys, no probs there, took the battery out and checked the main battery feed Plugs for corrosion, all ok there.
Had the car sitting with the ignition on while I was studying the wiring diagram and the wipers started working, got in the car and p/windows, mirrors etc where again working?
So I close the Bonnet, lock the car with the smart lock pad, come back to the car 15 mins later and again the same problem, stayed that way on the 50 k round trip I had to do.
Got home and locked it with the key, woke this morning and it all works once more.
Got to work locked it with the smart lock pad, reopened it with the key and now the same porblem.
Has anyone seen this problem before? Could it possibly be a smart lock issue?
Any help would be appreciated.

I dont see how. UNless your blowing the Smartlock fuse and that one fuse controls all those things then possibly yes. But Smatlock runs off is own computer chip so maybe its either a central locking issue or BEM issue.

doubt he blowing the smartlock fuse
the power windows would not runn of that circut

sounds like their is a dodgy wiring connection somewere. to the inside of th car,
you said u checked the battery terminals for corrosion.. what about the actuall vbattery clamps ( ie were the wire is ) what are they like.

Yeah their clean as frank, I took them little plates off and cleaned them in works sand blaster then wire wheel, soldered new ends on the main pos and neg leads, and made sure all the small neg/ pos are clean.
Was only a stab in the dark with the Smart Lock, the wiring diagram shows blue/yellow from SLM to Fan/Wiper relay, I think now is just coincidence that the fault was there after locking with the keypad and not with the key.
Thanks for the replies....

Sounds like a dodgy earth in the system.

Not all the acc's that you describe are on the same loom, which makes it all a bit strange.

Power windows are on a different loom to the rear demist, but may be earthed at the same point?

Yep i reckon it's the dodgy earth, earthing and then not.