Now that I have accidentally posted this in the wrong forums, I finally have the right one and I hope you can help.

This is weird.

The multi-switch harness plug started to go on my 99 Expy, you know, melting from too much current, and the turn signal wasn't working right.

So, I pulled it all apart and ordered a new switch. I added the headlight relay and I repaired both the harness and plug with epoxy and harness wrap. All good.

I put in the new switch and the wipers do not function properly; however, they do with the old switch. I spoke to the auto parts place and they said it must be defective, so they sent another. It does the same thing.

I put an ohm meter on the plugs and it seems as if the way it determines the mode for the wipers is to vary the resistance across 4 terminals.

The values on the replacement switch (only measured 1) is completely different than on the original one.

I am told and verified by the switch label, that the multi-switch is the same for the Expy and Excursion (label had 2000-01 Excursion). When I mentioned that to the parts people they said it was all the same part.

I think they may look the same, but electrically they appear very different.

When I turn the replacement switch on for wipers, they won't come on in delay and when they are set to full on and then off, they won't turn off until the key is switched off. When the key goes back on, they stay off, but still function in this weird way.

I'm thinking that Ford changed the way they did this and the replacement part isn't correct. Since the original switch works for wipers properly, then I know the GEM is good, right? I have no other electrical issues, no water on the GEM, none on the fusebox, etc.

Can anyone shed some light on this?

As usual, thanks in advance!

 

It sounds like the wrong switch to me...it should be an exact swap. I have had experiences where they have the wrong part number in their computers. So either try a different brand of switch if they have one, if not then try a different parts store.

 

A few years back I replaced the multi-function switch in my father's Lincoln. The part came from a local independent auto parts dealer. Worked fine except when the headlights were on, the blue "brights" light was on as well and stayed on whether it was the lowbeams or highbeams. Replaced with a legit FoMoCo part and all was fine.

Might be a the manufacturer of the switch as well. Just a thought.