vrracing

iTrader: (1)

The car has the relay mod and three new Mazda 6 switches (singles from the back seat) in custom vacuum formed cases. Everything has worked great for a year.

Then they stopped. We replaced one badly corroded relay in the passenger side. It was upside down and not sealed so car wash water must have gotten to it as it rarely rains in Austin.

Still didnt work. We found that when we'd used the window, the input voltage would drop from 12v+ to around 3v. This is measured from the lead to the door ground without the switches or motors in the circuit.

Hooked the door light to power the windows as an experiment and it did the same thing (12v -> 3v).

No fuses blew.

More monkeying around and they started working.

Then a week later they stopped. We put four new sealed relays and it still doesnt work.

My Googling says that given Ohm's law that there is resistance (usually corrosion) in the circuit somewhere. My guess as to why it is intermittent is that powering the windows puts enough load in the wire that the corroded or weak part of the circuit heats up and the resistance increases.

My youngest had a 91 MR2 and they were famous for electrical issues in the doors because the loom at the hinge flexed and the wires broke. I've never seen a reference to anything similar in the 7s but there are a LOT of window problem threads so I might have missed it.

Any suggestions on how to use a basic DMM to identify the culprit? I've read there are some special load type DMMs that are ideal for this kind of work but I dont have one of those.

Thanks

Jim

AGreen

iTrader: (11)

You likely have a faulty door ground. Try installing a temporary ground strap with some alligator clips to see what happens.

vrracing

iTrader: (1)

I'll do that, A. Thx.

Why do you think it is the ground?

jesseluck

iTrader: (2)

I couldnt make a good ground in the passenger side so I tapped into a door handle wiring.

SIDEWAYZE_FC

iTrader: (1)

I think this might be part of my power window problem on 88 vert. drivers door window works great but passenger side is like half the speed. just assumed it was gummed up in the window rails or something.

vrracing

iTrader: (1)

Sideways, you may need to do the relay mod and clean your switches. You may also want to look at the nylon 'pulley' at the top to make sure it isnt so worn that the cable is binding.