Windscreen wiper fault finding

[malcb]

Just reconnected the wipers on a '76 FJ45 and they don't work properly.

I get the low speed on the first pull, wipers stop if I pull the knob to the second position. Wipers don't park either.

Anyone know what I should look for, wiring was cut at the screen and I reconnected each to same.

 

[malcb]

Did another search and found Coolermans wiper science page. Think it's the ground connection at fault first off, high speed might be something else.

Thanks, something to work with now.

In case anyone else can't find the link IH8MUD Forums - View Single Post - The dumbest question i ever asked, wiper switch

 

[FF LC FREAK]

Just reconnected the wipers on a '76 FJ45 and they don't work properly.

I get the low speed on the first pull, wipers stop if I pull the knob to the second position. Wipers don't park either.

Anyone know what I should look for, wiring was cut at the screen and I reconnected each to same.

Mine do this if I plug the loom into the switch backwards. But that is on a 71 and it can plug in either way. I don't know how much difference there is between the two. Just something to think about.

 

[malcb]

Thanks, plug was missing but I think the wire reversal Mark mentions has something to do with it, probably same effect as you found.

Excellent write up Mark, when I looked at the schematic I was wondering why park switch put +12V on the brushes - if I understand the last line of you write up it prevents the motor coasting? Always amazes me how clever and yet simple the design on these vehicles is.

Looking at the mechanism today made me think of a triple wiper mod but it's not going to happen unless I widen a 40 series for an 80 series frame......

 

[bsmith123]

checking the wipers

"Did another search and found Coolermans wiper science page. Think it's the ground connection at fault first off, high speed might be something else."

You can troubleshoot this by shooting the lo/hi wires from the windshield back to continuity to ground. set to low ohms ---one lead of your meter on the wire the other to ground then pull the switch and check all the wires until you see the low ground
set switch to high then do the same on high
no ground in either of the pos is bad and shoot back from here to the ground to find the prob

for the motor side
find the blue wire and shoot continuity to the top contact of the park switch

then

find the blue wire that runs to the top contact on the park switch on the motor and run a wire from battery pos to that wire for the motor then run a ground wire and touch the remaining wires one at a time to find which wire makes it run on high or low---this will make sure the motor is not the prob


now that you know which is hi and low on both sides

for park check the continuity through the switch from blue black to the middle contact

from blue to the top contact

pull up the center contact until it touches the top and you should have continuity between blue and blue back---this is the park position

let go and you should have continuity to ground on blue black

it is this ground that allows the wipers to run in the off position until the park switch opens


sheesh I think I got that right but you can see the methodology anyway---

find the high and low grounds off the switch
in off shoot through the 2 wires for continuity that would connects the low brush through the switch to the park switch ground in off

then check power to the motor and run the motor in low and hi

then check the function of the park switch

 

[malcb]

Thanks,

Hopefully I get to try this tomorrow, otherwise Monday, better see where I put the blades.

 

[malcb]

OK.

First the bullet connector wiring that crossed on Mark Coolermans 71 doesn't seem to need reversing on my 75, will check the 76 which is 100% stock with no PO hacking. (I am the second owner, PO even give me the bit of the front bumper that got torn off on a tree stump, only thing missing is whats turned to rust and dropped of )

Other wise the wiring was as described by Mark in his writeup.

Park needed a better earth to work reliably. Hi speed didn't work but the wiring checked out, then it suddenly did but not smoothly - found if I wiggled the wire where it goes into the motor it went better = brushes?

No bad for a 34 year old vehicle which hasn't been running for at least 7 years.

While working on my wipers I happened to pick up the rear window wiper from a Fiat that someone had changed last week. Noticed that the wiper motor would actually fit inside the windscreen frame, gearbox is all wrong but I might have a look at the possibilities of fitting such a unit. Also noticed the park function was built into the Fiat unit, only single speed though.

 

[lobo loco]

OK.

First the bullet connector wiring that crossed on Mark Coolermans 71 doesn't seem to need reversing on my 75, will check the 76 which is 100% stock with no PO hacking. (I am the second owner, PO even give me the bit of the front bumper that got torn off on a tree stump, only thing missing is whats turned to rust and dropped of )

Other wise the wiring was as described by Mark in his writeup.

Park needed a better earth to work reliably. Hi speed didn't work but the wiring checked out, then it suddenly did but not smoothly - found if I wiggled the wire where it goes into the motor it went better = brushes?

No bad for a 34 year old vehicle which hasn't been running for at least 7 years.

While working on my wipers I happened to pick up the rear window wiper from a Fiat that someone had changed last week. Noticed that the wiper motor would actually fit inside the windscreen frame, gearbox is all wrong but I might have a look at the possibilities of fitting such a unit. Also noticed the park function was built into the Fiat unit, only single speed though.

If it's any consolation, I have the exact opposite problem on my '78...Wipers work on hi-speed ( I use the term loosely) & they park OK, but nothing on low speed...but then again I'm not sure what low speed really is as they have never worked on low since I've had the truck, but I can safely say if they are moving...I could never tell! Took the motor apart and the brushes are fine...lubed up the shaft of the motor, polished the armature a bit with 600 grit paper. Put it back together and everything still works the same. No low speed. I tried another wiper motor I had received with a bunch of other cruiser junk and it works the same way, so I'm reasonaby sure it's the switch or somewhere in the wiring. Anybody know a way to jumper the motor to test out the two speeds? I tried to decipher the schematics but switch pics have me a bit lost. Right now I'm thinking it may be the switch, but didn't feel like doing the under the dash contortion thing to find out. If I ever get the desired results, I will test the spare motor and offer it and the arms assembly up for sale to one who is in need.

 

[bsmith123]

"Anybody know a way to jumper the motor to test out the two speeds? I tried to decipher the schematics but switch pics have me a bit lost. Right now I'm thinking it may be the switch, but didn't feel like doing the under the dash contortion thing to find out. If I ever get the desired results, I will test the spare motor and offer it and the arms assembly up for sale to one who is in need. "


Yes a couple posts back
but on a 78 maybe the wire colors are different

no matter you can do this

if your connectors are intact separate the connector at the motor
pull the switch to low and on the connector that has the wires going back to the switch shoot for a ground (Continuity)
If you are not familiar with this then set your meter to the lowest ohms setting and touch bare metal with the black lead and the wire with the red lead
when you find the wire with continuity to ground that should be the low speed position--verify by going to hi and back to low and watch it go open in high and continuity in low



now look at where that wire goes on the motor connector. Run a jumper to ground from that wire on the motor connector
Set your meter to VDC and on the connector side check for 12 volts with the switch in low.
You can also shoot the motor connector wires to the top contact on the park switch for continuity to find the power wire.
Now make a jumper to go from batter pos and touch it to the corresponding wire on the motor connector

Now they should run in low---same procedure to find HIGH just shoot to ground at the switch in high to find the right wire to ground


Dont have a meter? well go buy a cheap one! Or in a pinch you could do this with one of your side lights use the ground side of the light to connect to the wire going to ground through the switch for low or hi pos. Then jumper power to the light ---if it lights you have found the wire, if not wrong wire, in this circuit you are not gonna mess anything up putting power to it as long as you dont put power straight to the ground---it has to go through the light!


in the schematic above that would be

motor side connector
LW to ground or battery neg
L to 12 vdc (battery POS)

with those jumpers the motor should run in low

switch the ground to LR for HI

L without the park switch is the power wire

Have a good read on Coolermans wiper science and have a good look at the schematic. Note that park is voltage on both hi and low at the same time and look at the switch schematic the little gray box is the solid metal contact as you move it it connects the posts on top and bottom. all the way left is off, then to the right low, and finally high

if you need it I can give you step by step to shoot through the switch but since it is only happening in low I think you will be good

Hope that helps

 

[malcb]

I would just add if you wipers park the low speed must be OK as the circuit makes the park on the low speed brush.

Least that is how it looked to me.

 

[bsmith123]

"but then again I'm not sure what low speed really is as they have never worked on low since I've had the truck, but I can safely say if they are moving...I could never tell! "


Good Point!

Low should be okay as far as wiring and the motor if they are parking, but it could be a damaged or dirty contact on the low contacts in the sw as opposed to the contacts in the off pos. Might just need to clean up the switch where the sliding contact meets the #1 and 4 contact

 

[Coolerman]

bsmith123 has been doing a great job explaining how all this works so I stayed out if it.

Here are a couple of things to check if you get intermittent function.

First, pull the motor apart and look for poor connections at the brushes. Don't forget the jumper on the back of the board...

Second, the commutator could be burned, pitted, or coated with a poorly conductive coating. It needs to be cleaned, and lightly sanded or use a tool designed just for this purpose. Don't forget to dress the brushes. This can make the motor run like new.

 

[lobo loco]

First, let me thank you all for the info and your help. And yes, I have a good digital VOM, and know how run continuity checks. I went thru the whole thing again today and still no real change. Pulled the switch out of the dash...checked continuity across the contacts on the switch..all are good and have continuity as they should back to the blades in the connector from the solder joints on the top of the switch. Also pulled the motor apart again and checked everything, brushes are good, dressed the contact area with a hand held dremel sanding drum, checked the leads, springs, etc...no binding anywhere. All check out good....but still no low speed. Park OK, wipers run on the high speed (2nd) position, park when turned off. When I move the switch out to the 1st position (low) after being parked, the blades move about 1/2" then stop and nothing more. BTW, I have the blades flipped out from the windhield, so there is no drag on them. I'm at a loss as to what the heck is keeping the low speed from running. Any more ideas?

 

[bsmith123]

jumper

Try jumpering the low speed terminal on the w/s connector to ground that will rule out wiring and switch for sure. A meter can prove it bad but does not really prove it good as it only takes a strand of wire to get continuity. Bypassing half of the circuit will prove where the prob is and cut your t/sing in half

Did you get continuity to ground through the windshield connector with the switch in low?

check the adjustment of the contacts on your park switch too, could it be parking in low?---see if there is power on the park wire in low (low and park wire swapped?)

let us know how it goes

 

[lobo loco]

Try jumpering the low speed terminal on the w/s connector to ground that will rule out wiring and switch for sure. A meter can prove it bad but does not really prove it good as it only takes a strand of wire to get continuity. Bypassing half of the circuit will prove where the prob is and cut your t/sing in half

Did you get continuity to ground through the windshield connector with the switch in low?

check the adjustment of the contacts on your park switch too, could it be parking in low?---see if there is power on the park wire in low (low and park wire swapped?)

let us know how it goes

Too late today to tear into it again, but here's some additional info I found from my last attempt. At one point, I removed the gearbox cover and ran the motor with it off. No change this way, so I doubt that park was being activated. I should note that there are three fingers(contacts) on mine and two of them rest on portions of the ring gear that have interuptions on them... the interruptions are of different length ( one contact makes contact all the way around), not sure why there are two as it would seem like one would do to park the things. On the other motor I have which is an earlier type I believe, there are only two contacts. Another bit of info...a friend came by today with his 77 ( brought me the two diff carriers from his truck!! as he put ARB lockers on each end and I needed a set of spiders to get rid of my Lock-Right...but this is another topic completely) Anyway, I asked him to turn on his wipers so I could judge the two speeds and my motor is definitely running on the higher speed equivalent to his hi-speed, as slow is only about 25% slower. I may well have to settle for the hi-speed only, but this thing has me perplexed and something I really want to figure out, before I start buying parts to swap. I'll try to snap some pics as I'm wondering if the motor I have is even the right one for the truck or something the PO threw in to make the wipers work. Again, thanks for the help.