Login|Contact Us
Question and Answer

Jeep

Ask a Jeep Question, Get an Answer ASAP!

  • Ask A Question
  • Browse Answers
  • Meet The Experts
  • How JustAnswer Works

Jeep Grand Cherokee: 1993 Grand Cherokee. the rear window motor

 

Customer Question

1993 Grand Cherokee. the rear window motor went out. took the regulator out and replaced the motor. now, the motor only operates in the down direction. i jumped the motor to voltage and it does work in both directions. i back probed the switch and both sides of the motor connector and there is 12.5v at each step. then i disconnected the motor and jumped it from the switch and it works in both directions. it just quits working in the 'up' position when i plug the motor in. i've tried two switches and i get the same thing. i've been on this thing all morning and i need a break and a new perspective. any thoughts?

 

Country: United States
Make: Jeep
Model: Grand Cherokee
Year: 1993
Engine: 4.0

Already Tried:
swapped switch, jumped motor to voltage, jumped motor to switch. pulled my hair out.

Submitted: 258 days and 6 hours ago.
Category: Jeep
Value: $18
Status: CLOSED
Picture
Expert:  molurch replied 258 days and 6 hours ago.

 

 

which door?

 

 

Customer replied 258 days and 6 hours ago.

sorry, left rear

Picture
Expert:  molurch replied 258 days and 6 hours ago.

 

 

Thanks for using J/A / Pearl
My answer is below.

Please understand, the site makes me post the following:

"Please only rate my answer if you are satisfied with the service I have provided.
If you feel the need to rate "Poor Service" or "Bad Service", please stop and reply to me via the REPLY TO EXPERT button with the issue you have, because this will result in a negative mark on my feedback record.
I will be happy to continue further and do everything I can to provide you with the service you seek.
Instead, please simply reply to me via the REPLY TO EXPERT link with the issue you have.
I am happy to continue further and do everything I can to provide you with the service you seek."
My answer may not be to your liking, but is a correct & honest answer.
Many times the only fix will be by Dealer or Shop, so please do not hold that against me.


------------------------------------------------------------------------------------------------------------

sounds like you have one "leg" missing.......


The Circuit for the Power Windows is "Reversal Rest at Ground"
Meaning that the Voltage & Ground "reverse" at the switch
There are "2" wires at the Window Motor
with Switch up......one wire will have 12 Volts +.....the other wire will have Ground -
with Switch down.....the wire that had 12 Volts + now has Ground - ..... the wire that had Ground - now has 12 Volts +

 

TESTING at the Window Motor:

 

Use of a VOM is needed to test
The way it works:
Ignition On
Switch held in Up position
One wire will have 12 Volts +
One wire will have Ground -

 

Switch held in Down position
The wire that had 12 Volts + is now Ground -
The wire that was Ground - is now 12 Volts +

 

If Voltage or Ground checks good at motor, replace motor.
If Voltage or Ground does not check good:
Check Switch Voltage & Ground.
Check for broken wires at Door / Kick Panel Boot

 

 

 


If you need further, please ask "before" you Rate my Answer...............

 

If not, please rate my Answer as Excellent Service, as that is how a recieve a small portion of the Deposit................thank you

 

 

 

 

 

Customer replied 258 days and 4 hours ago.

okay. so here's what i did.
i probed the switch for B+ and Ground. both of which were good.
then i used wire piercing probes on the motor side of the connector. with the switch in one direction, no voltage, with the switch in the other direction i got about 5.6V. i checked the switch and both wires switch from power to ground when you operate the switch. the condition is the same with two different switches. the drivers front switch is dead. is this one of those deals where if the gang switch is dead, then the corresponding single switch wont work right?

Picture
Expert:  molurch replied 258 days and 4 hours ago.

 

 

with the switch in one direction, no voltage, with the switch in the other direction i got about 5.6V.

??
very low
vehicle starts & runs?

is this with the Window Motor unplugged?
If not what is it with it unplugged?

 

 

Customer replied 258 days and 4 hours ago.

vehicle starts and runs. i've kept a charger on the battery while i'm testing. the B+ wire going into the switch has 12.5V.

with the motor unplugged, i get 11.87V in the same direction, no V in the other.

Picture
Expert:  molurch replied 258 days and 4 hours ago.

 

 

with the motor unplugged, i get 11.87V in the same direction, no V in the other

 

Remember.......one wire shows Voltage +, one wire shows Ground - with switch up or down.
If you are getting 11.87v to one wire & Ground - to the other, then the Motor has to move
"unless" it is all the down or all the way up & switch is to one of those positions
or
the Motor is bad

or

you do not have Voltage + at the Motor or a Ground -

 

 

 

Customer replied 258 days and 4 hours ago.

okay. i think i overlooked something.

i'm probing the back of the switch with a dual test light. the one wire shows ground and hot when switched. the other shows hot only. there is voltage on both wires when there should be. its the same with two different switches. it cant be the wire because its carrying current and has continuity. so do i have 2 bad switches?

Accepted Answer

Picture
Expert:  molurch replied 258 days and 3 hours ago.

 

 

the switch works in both directions. with the motor unplugged, there is ~11V in either direction.
ok


i checked it with a dual test light. both wires switch from ground to power.
ok


with the motor in the full down position, the voltage drops.

with the motor in the full up position, there is full voltage.

you are only pointing out Voltage +
There has to be Ground -on the other wire for the Motor to move, at the same time the first wire gets Voltage +


You originally stated:
the motor only operates in the down direction

If the Window Motor does NOT operate in the Up direction & you have Voltage on one wire, then there is NO Ground - on the other with Switch held in the Up position.

 

the front gang switch is inoperative for the left rear window

 

I missed that..............sorry........

Do this
Key On
Should have VIOLET wire & BROWN wire at the Rear Door Window Motor
With Switch held in Up position, check to see which wire has Voltage +
Supply a "brief" Ground - jumper wire to the "other wire" while holding switch in Up position
Window should move

 

If so, then you will need to "back probe to find the broken wire or connection of the wire that you connected the Jumper Ground to

 

 

 

 

 

 

 

Expert TypeMechanic
Category: Jeep
Pos. Feedback: 95.8 %
Accepts: 352
Answered: 8/2/2012

Experience: Chrysler Warnty, Heavy Line Mech, Mobile Electronics. Sales, Installation & Repair for 30 years

Ask this Expert a Question >
 
Tweet

15 Jeep Mechanics are Online Right Now

Ask Your Question Now
Jeep Questions Date Submitted
Grand cherokee laredo: I have an after market command starter 3/28/2013
grand cherokee limited: i have the same problem with my jeep. 3/28/2013
cherokee: 1997 jeep cherokee 4.0 wont start from key but can 3/28/2013
4.7 liter v-8 jeep grand cherokee: my girlfriend was driving 3/28/2013
grand cherokee: 2009 jeep grand cherokee w/3.7l engine had 3/27/2013
grand cherokee: my daughter has a 2001 jeep grand cherokee, 3/27/2013
cherokee sport: i have a 2000 jeep cherokee sport hand new 3/27/2013
Jeep Liberty Limited: i use a 2003 jeep liberty. It gives me 3/27/2013
RA-JM 3/27/2013
jeep grand cherokee: hello I have a 03 jeep grand Cherokee 3/27/2013
RSS
Next 10 >
Ask A Jeep Mechanic
Type Your Jeep Question Here...
characters left:

Top Jeep Experts

See More Jeep Mechanics

In The News

Nbc
Washington Post
New York Times
Cnn
Learn More

How It Works

  • Ask an Expert
  • Get a Professional Answer
  • Ask Followup Questions
  • 100% Satisfaction Guarantee
Learn More
close
Find Expert answers related to your question.
Sign up using email
We will never post anything without your permission.
Already have an account? Sign in

Ask a Jeep Mechanic

Get a Professional Answer. 100% Satisfaction Guaranteed.
191 Jeep Mechanics are Online Now
Type Your Jeep Question Here...
characters left:
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.
Truste
Contact Us | Terms of Service | Privacy & Security | About Us
© 2003-2013 JustAnswer LLC