1992 Silverado p/u very strange problem

[pfindlay]

I have a 92 Silverado 2500 pickup (350 fuel injected, 4L80E trans) which has developed the strangest problem.

I pull a trailer with an antique car on it. When pulling up a hill, sometimes the alternator light will flash a few times and then the gauges and speedo will all flick and the transmission go into a neutral. As soon as I back off on the throttle it goes back into gear and all is normal again. If I back off as soon as I see the alt light flash I can usually avoid the subsequent symptons. It seems to happen at higher revs, such as if I have pulled it into second to pull up the hill. No memory codes are stored during this event.

I've never had this happen without a load on the back. I've disconnected all trailer wiring and it still happens, so it is not related to the trailer itself.

I'd be interested in hearing any thoughts on what could be causing this problem. Electrical? ECM? Transmission? Why does it always begin with the alternator light?

Just yesterday the SES light came on and a code 32 was read, but I don't believe this is related to the problem.

Peter