Nissan Repair: 98 Altima Power Window - doing the impossible, nissan altima, motor amps

Question
QUESTION: Wow, I'm glad to have found this forum, because I definitely need an expert here.  The wife's 98 Nissan Altima driver's side power window started acting up the other day -- would only go down, no sound or activity when pulling switch up.  I'm not a complete rookie, and have replaced power window motors/regulators before.  When I got her door panel off, I pulled apart the connector between the switch and the motor.  I put a multi-meter on the switch side of the connector and got 12 volts when pressing switch down, and -12 volts when pulling for up (just as expected).  I pulled the motor and regulator, then put a separate power supply on the motor and the motor turned clockwise.  Reversing the pos/neg wires from the battery reversed the motor direction (again, just as you would expect).  But when the motor is connected to the switch, (but not to the regulator, so no load) with the multimeter probes inserted into the connector, I only get a voltage reading when the button is pressed, I get nothing when it is pulled up. Now I know it isn't possible for the switch and the motor to work properly separately, but not to work when plugged together - but since that's what is apparently happening, I'm hoping you have some thoughts on the matter.

ANSWER: Hi Jim -

Funny, I just finished working on an Altima last week. Was a 2002 model though.

What you describe seems to be a defective motor. I am not sure how you hooked it up the second time, but when you connect it as a unit, it takes you through all these relays and limit switches. Because it takes a lot more (motor)amps to get the window up the track as opposed to down, a failing motor would probably trip the high limit switch and cause the window not to work. However it will still run unloaded. I believe this is what's happening. In any case replace the motor and you should be god to go -

Hope this helps -
aloha
Calvin

---------- FOLLOW-UP ----------

QUESTION: Calvin~

Thanks for responding so quickly.  Perhaps you're right, and it's a defective motor, but just for the sake of discussion... I actually did buy a replacement motor, but never fully installed it.  I connected the motor to the plug leading to the switch (remember the connector shows +12 volts when the button is pressed, and -12 volts when the button is pulled up, so everything seems good up to that point.)  When I connected the new motor (with no load, not even connected to the regulator, just holding the motor in my hand) the motor would spin when the button was pressed down, but did nothing when the button was pressed up, just as the original motor did.  Thus I'm not discounting it entirely, but I'm not convinced that both the original and brand new motors are defective.  I did not consider the different amp requirements for up vs. down, though -- is there a fuse or relay somewhere that might inhibit the current on the "up" mode??  Could such a problem originate in the switch itself such that it shows voltage when the switch is pulled, but doesn't have enough amperage?

Answer
Hi Jim -

No problem. just happened to be on line.

I did not realize you had a second motor. I agree with you that it would be highly unlikely that both motors are defective. I'd say 90% of the time these go out, it is the motor. the Altima I just fixed was the same. Had power only one way (down).

Anyway, the relay is integrated into the switch, so now I would look at replacing the switch, with the new information you just gave me. Perhaps I have been "lucky" all these times replacing the motors. I did not get into circuit testing as deeply as you did. Perhaps i should start doing that - LOL

Aloha
Calvin