The essentials of Power Window System troubleshooting

[Doctor J]

The purpose of this "masterpiece" is to explain the main differences between power window systems used in early and late 80s Toyotas and to provide troubleshooting guide for these who will attempt to tackle electrical problems in power window systems.
Although the troubleshooting guide is written specifically for second generation Camry [1987-91] power windows repair it can be used for similar models [Cressida, Corolla]

The system used in late 70s and early 80s used 3 brush reversible motors. In such motors, three brushes were spaced 120 degrees apart with one brush was connected to the ground. The power window switch [single pole double throw] used to connect power to the either one of two “positive” brushes which let the motor to turn either clockwise or counterclockwise.
Therefore if motor runs in one direction only it can indicate bad switch, bad “positive” wire from switch to the brush or the defective motor itself.
If motor is not moving at all the power supply to the switch and ground wire from the motor must be inspected first. Note:3 wires are going out of the motor below.

I have had such system on my 79 Supra and never have problems with it.
The newer system used on 2nd generation Camry, used 2 brush conventional motor similar to one used on 81 and later GMC cars. In such system the reverse motion of motors was achieved by switching the polarity applied to the brushes. The motor itself and its control circuit are insulated from the ground.
Therefore if motor rotates in one direction only [window goes up but not down or wise versa the motor is good and don’t have to be replaced.
Although this system is a lot more complicated then the old one,12 V test light and few jumper wires are needed for voltage tests and/or simple analog Ohmmeter is needed for continuity testing.
The single common ground wire of conventional color [W-B] goes from the master switch to the point “D” on the body. The Power wire [light blue], on the other hand, comes to all switches [4 places] from Power Main relay and 12 V are present only with Ignition ON [Hot at Run, using GM terminology]. Therefore, if all windows are not working either from master switches or from on the door switches:

• Pull the master switch out of the door, leave wires connected;
• Install “parallel” ground to the ground wire [you can do it by pushing the paper clip into the cavity where the white/ black wire is coming out, until it touches back of its terminal [aka back probing] and then attaching this clip to the good ground using the jumper wire
• Turn ignition ON
• If windows are working, then fix the common ground wire[front door –kick panel]

If this does not help, verify that power is present on the thick blue wire.
If no power is present, check the relay or circuit breaker.[in this case some other circuits will be affected]; such problem in most cases caused by mechanical failure[frozen motor or jammed window regulator; in this case the system will work until the jammed window will be allowed to operate].
If all windows except the one in the drivers door are operating from their own switches, but not from the master switch :

• Check that power is present on the blue wire at the master switch with ignition ON
• If not , repair the power wire to the master switch
• If yes remove and inspect master switch assembly

If window operates from master switch but not from its local switch, check for the power at blue wire at the local switch:
· If no power is present repair the blue wire
· If power is present inspect the local switch
· The quick way to check the local door switch is done by unplugging the connector and then installing jumpers between the wires: plain green and the green with the stripe and plain red and the red with the stripe by jumping the terminals 1 to 2 and 3 to 4, on the local switch connector leaving the blue wire [terminal 5] alone. [EWD90, Pages102-103]

If one or two windows are not working either from master switch or its local switch and power is present at the blue wire similar to above test, note the following:

“When all switches in NEUTRAL position BOTH wires from the each motor are connected to the common ground wire by master switch”

Therefore using the diagram, locate the pair of wires from local to the master switch and check each wire for continuity:

• If no continuity, repair the wires
• If there is continuity, inspect the motor [apply power to red and green wires]
• If motor is good inspect the switches.

This method should help to make the troubleshooting process easier

[shayzj]

Thanks Doc. Most informative.

Shay

[Kep]

Thanks Doc, great DIY

Kep

[nuron]

I'm just curious, will motors from newer Camrys or other models work? I feel like all of the Gen 2s are nearing the end of their working life like mines have recently.

http://seattle.craigslist.org/kit/pts/962260114.html

[Doctor J]

Iam not aware of part interchange info, but in the way they are controlled they are the same

[es250nut]

Dr. J, Might I suggest this addendum to your Guide:


If a Window will only go down from both the master and local switch but not back up check the continuity of the red based wire and master switch for that window from the drivers side door. (In a gen2: Front Right = Red/blue, Rear Left = Red/Yellow, Rear right = Red/Black)

Conversely if a window will only go up from both the master and local switch, but not back down check the continuity of the green based wire and master switch from the drivers side door. (In a gen2: Front Right = Green/blue, Rear Left = Green/Yellow, Rear right = Green/Black)

[Doctor J]

Thanks for letting me know; I was writing my guide four days after repair, during which I did not have chance to write notes [it was done at 8 pm on Sunday, and the car has to be ready by Monday, 6 am].
In the near future I would have another opportunity to diagnose this system, so I going to take good notes and pictures, and most likely will re-write procedure.
"Seat belts" is my current project; will post it after doing my "article review' for postgrad class [you know, writing is not what I like to do].

[aussie_gen1]

Great idea for an article. I had problems with one-way windows from the master switch on my gen 1 soon after I got it, so I pulled the window switches apart and cleaned them thoroughly, not a problem since. Quite a crap buildup after 20+ years of use, like any switch I guess. It feels really good to have a 25 year old car with perfectly working electric windows though (touch wood)