How to check a switch using a multimeter and a function matrix?
Thread Starter
Melting Slicks
Joined: Oct 2005
Posts: 2,056
Likes: 8
From: Redruth Cornwall
How to check a switch using a multimeter and a function matrix?
Using one of Willcox's repair procedures but am having a few problems trying to test the switch.
Its a 79 wiper switch that I have repaired and I just want to check out the connections etc because it didnt work when I re fitted it...lol.
In the function matrix there are x's in various boxes. Am I to assume I should get continuity between the x's only depending on switch position?
At the mo I seem to be getting continuity between more than just the x boxes
Also, on a 79 did any come with non intermittent wipers?
Its a 79 wiper switch that I have repaired and I just want to check out the connections etc because it didnt work when I re fitted it...lol.
In the function matrix there are x's in various boxes. Am I to assume I should get continuity between the x's only depending on switch position?
At the mo I seem to be getting continuity between more than just the x boxes
Also, on a 79 did any come with non intermittent wipers?
Burning Brakes
Joined: Aug 2005
Posts: 1,164
Likes: 1
From: Europe, France
I suppose you're testing the switch without any device/accessories connected to it.
In this case, you should logically only get continuity where the x's are, and nowhere else.
That means your multimeter should indicate an infinite resistance where you have no x's in the function matrix.
If you get continuity, something is probaly wrong.
Sorry, can't help you about the non-intermittent wipers...
In this case, you should logically only get continuity where the x's are, and nowhere else.
That means your multimeter should indicate an infinite resistance where you have no x's in the function matrix.
If you get continuity, something is probaly wrong.
Sorry, can't help you about the non-intermittent wipers...
Thread Starter
Melting Slicks
Joined: Oct 2005
Posts: 2,056
Likes: 8
From: Redruth Cornwall
Thats what I thought. Will strip down the switch again and see if I made a mistake somewhere.
From what I can see, all the switch does is ground the wires thus completing the circuit.
Does the following sound right. Im looking at the function matrix now.
Wash = Ground and terminal 94 ( pink wire connected to the washer )
High speed = Ground and terminal 92 ( purple wire connected to #3 terminal on the wiper motor )
Low speed = Ground + terminal 91 ( gray wire ) and terminal 92 ( ie grounding both terminal #1 and #3 on the wiper )
Off = Ground and terminal 91 ie low speed terminal?
Not sure why the off position has grounded out the low speed terminal as in the wiper testing article on the Willcox site, it says if you apply power to the the center (#2) terminal of the wiper, it should park when the grounds are removed from the outer 2 terminals, #1 and #3.
Also, not sure if it makes much difference but my wiper motor looks a little different to the one shown on the willcox test instructions.
Am I correct in thinking the black cable to the left of the 3 wire connector is the ground cable?
Does that make sense?
From what I can see, all the switch does is ground the wires thus completing the circuit.
Does the following sound right. Im looking at the function matrix now.
Wash = Ground and terminal 94 ( pink wire connected to the washer )
High speed = Ground and terminal 92 ( purple wire connected to #3 terminal on the wiper motor )
Low speed = Ground + terminal 91 ( gray wire ) and terminal 92 ( ie grounding both terminal #1 and #3 on the wiper )
Off = Ground and terminal 91 ie low speed terminal?
Not sure why the off position has grounded out the low speed terminal as in the wiper testing article on the Willcox site, it says if you apply power to the the center (#2) terminal of the wiper, it should park when the grounds are removed from the outer 2 terminals, #1 and #3.
Also, not sure if it makes much difference but my wiper motor looks a little different to the one shown on the willcox test instructions.
Am I correct in thinking the black cable to the left of the 3 wire connector is the ground cable?
Does that make sense?
Last edited by jotto; Oct 5, 2009 at 10:53 AM.
Burning Brakes
Joined: Aug 2005
Posts: 1,164
Likes: 1
From: Europe, France
Maybe you could send a PM to Durango_Boy or ...Roger...
http://forums.corvetteforum.com/memb...rango_boy.html
http://forums.corvetteforum.com/memb...6--roger-.html
I noticed there are very good at solving electrical issues, amongst other things...
http://forums.corvetteforum.com/memb...rango_boy.html
http://forums.corvetteforum.com/memb...6--roger-.html
I noticed there are very good at solving electrical issues, amongst other things...
Thread Starter
Melting Slicks
Joined: Oct 2005
Posts: 2,056
Likes: 8
From: Redruth Cornwall
Maybe you could send a PM to Durango_Boy or ...Roger...
http://forums.corvetteforum.com/memb...rango_boy.html
http://forums.corvetteforum.com/memb...6--roger-.html
I noticed there are very good at solving electrical issues, amongst other things...
http://forums.corvetteforum.com/memb...rango_boy.html
http://forums.corvetteforum.com/memb...6--roger-.html
I noticed there are very good at solving electrical issues, amongst other things...
Instructor
Joined: Jul 2008
Posts: 123
Likes: 0
From: Allentown PA
Yes, I believe the one black wire on the wiper motor is a ground.
With your wiper switch removed from the wiring harness, connect one lead from your multimeter to the ground terminal of the switch. Use an alligator clip so it stays put. You will touch the other lead to the other pins momentarily to check for continuity. Start with the switch in the OFF position. If I am reading my '79 schematic right you should get continuity when you touch the other meter lead to the LOW terminal and continuity when you touch it to the DISABLE DELAY WIPE terminal. Now confirm there is NO continuity on ANY of the other terminals, if there is not, the switch is good so far. If there is continuity on any of the other terminals STOP and find the problem. Repeat test with switch in each of the other positions such as MIST, LOW, HIGH, etc.
With your wiper switch removed from the wiring harness, connect one lead from your multimeter to the ground terminal of the switch. Use an alligator clip so it stays put. You will touch the other lead to the other pins momentarily to check for continuity. Start with the switch in the OFF position. If I am reading my '79 schematic right you should get continuity when you touch the other meter lead to the LOW terminal and continuity when you touch it to the DISABLE DELAY WIPE terminal. Now confirm there is NO continuity on ANY of the other terminals, if there is not, the switch is good so far. If there is continuity on any of the other terminals STOP and find the problem. Repeat test with switch in each of the other positions such as MIST, LOW, HIGH, etc.
Racer
Joined: Sep 2007
Posts: 286
Likes: 0
From: Pensacola Fla
wipers
Yes,you could get a 79 Corvette without the intermittent wipers if you did not order RPO ZX2,Convenience Group,includes other features right side visor mirror,dome and courtesy light delay,headlight warning buzzer,low fuel light,underhood light and floor mats.I think you can still find non intermittent wiper switches,but you will have to more then likely get a used intermittent wiper switch if you needed one if you can find one.
Safety Car
Joined: Oct 2007
Posts: 4,358
Likes: 1,724
From: Seattle Area Washington
Thats what I thought. Will strip down the switch again and see if I made a mistake somewhere.
From what I can see, all the switch does is ground the wires thus completing the circuit. Correct
Let's assign the chassis ground it's correct circuit number, that is 150.
Does the following sound right. Im looking at the function matrix now.
Wash = Ground and terminal 94 ( pink wire connected to the washer ) Correct, circuit 94 & 150 connected
High speed = Ground and terminal 92 ( purple wire connected to #3 terminal on the wiper motor ) Correct, circuit 92 & 150 connected
Low speed = Ground + terminal 91 ( gray wire ) and terminal 92 ( ie grounding both terminal #1 and #3 on the wiper ) Correct, circuits 91 - 92 & 150 connected
Off = Ground and terminal 91 ie low speed terminal? Correct, the reason circuit 91 & 150 are connected in the OFF position the wiper motor needs to continue to run until the wiper motor has finished it's cycle and parked.
When the wiper motor comes to a stop in its HOME or park position a set of internal contacts open (opening the circuit path between Shunt & Series windings).
Willcox was a very good supporter of this forum for many years, I just disagree with Ernie. Circuits 91 & 150 are connected in the OFF position period.
My wire colors are for a 1977, but same park switch was used 75-82
Not sure why the off position has grounded out the low speed terminal as in the wiper testing article on the Willcox site, it says if you apply power to the the center (#2) terminal of the wiper, it should park when the grounds are removed from the outer 2 terminals, #1 and #3.
Also, not sure if it makes much difference but my wiper motor looks a little different to the one shown on the willcox test instructions.
Am I correct in thinking the black cable to the left of the 3 wire connector is the ground cable?
Does that make sense?
From what I can see, all the switch does is ground the wires thus completing the circuit. Correct
Let's assign the chassis ground it's correct circuit number, that is 150.
Does the following sound right. Im looking at the function matrix now.
Wash = Ground and terminal 94 ( pink wire connected to the washer ) Correct, circuit 94 & 150 connected
High speed = Ground and terminal 92 ( purple wire connected to #3 terminal on the wiper motor ) Correct, circuit 92 & 150 connected
Low speed = Ground + terminal 91 ( gray wire ) and terminal 92 ( ie grounding both terminal #1 and #3 on the wiper ) Correct, circuits 91 - 92 & 150 connected
Off = Ground and terminal 91 ie low speed terminal? Correct, the reason circuit 91 & 150 are connected in the OFF position the wiper motor needs to continue to run until the wiper motor has finished it's cycle and parked.
When the wiper motor comes to a stop in its HOME or park position a set of internal contacts open (opening the circuit path between Shunt & Series windings).
Willcox was a very good supporter of this forum for many years, I just disagree with Ernie. Circuits 91 & 150 are connected in the OFF position period.
My wire colors are for a 1977, but same park switch was used 75-82
Not sure why the off position has grounded out the low speed terminal as in the wiper testing article on the Willcox site, it says if you apply power to the the center (#2) terminal of the wiper, it should park when the grounds are removed from the outer 2 terminals, #1 and #3.
Also, not sure if it makes much difference but my wiper motor looks a little different to the one shown on the willcox test instructions.
Am I correct in thinking the black cable to the left of the 3 wire connector is the ground cable?
Does that make sense?
Not sure why the off position has grounded out the low speed terminal as in the wiper testing article on the Willcox site, it says if you apply power to the the center (#2) terminal of the wiper, it should park when the grounds are removed from the outer 2 terminals, #1 and #3.
Also, not sure if it makes much difference but my wiper motor looks a little different to the one shown on the willcox test instructions.
Am I correct in thinking the black cable to the left of the 3 wire connector is the ground cable?
Does that make sense?[/QUOTE]
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