Friend persuaded me to wash engine bay... now no alternator

Last weekend my friend was over and he said that I should wash the engine bay as it was very dusty.

I was apprehensive so i didn't go crazy and just used a hose on low and some detergent. Then I put the car away in the garage. (1995 456GT)

I just went to start the car and I noticed that the battery light stayed illuminated. 11.72 volts at the battery with the engine running. The belt is tight and the alternator is turning.

I have a spare 456 alternator on the shelf but I though I'd check on here to see if there was anything else to check before I replace the alternator?

The existing alternator is about 5 years old and probably has 12,000 miles on it.

Any thoughts greatfully received.

 

The alternators was working fine when I put the car away. I wonder if it's a coincidence.

So, it's in with the new alternator next weekend I guess?

 

Thank you. I will try this next.
I was surprised that a relatively small amount of water from my cleaning could kill an alternator. It is quite protected from above as the plastic covers look to protect from above and the sides.

Where these alternators are unprotected is from below, where they seem to be entirely open to the elements. Certainly any decent puddles of water in the road after or during heavy rain would soak the alternator way more than my light cleaning of the engine bay (I avoided spraying water on the actual engine as much as possible.)

I will try electrical contact cleaner today and report back.

 

Electrical contact cleaner made no difference, so I changed the alternator today and everything is working again. It was lucky that I had a spare on the shelf.

Now to get the faulty one refurbished.