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I’m trying to get my wipers going on my ’68. The prior owner of my car said the wiper motor was shot. The car has 35,000 miles. This motor has 4,000 miles on it despite being installed 20 years ago. Records indicate the dealer in ’95 burned up another new motor due to a bad ground before installing this one. The currently installed, non-operable replacement is a 1969+ motor. I’ve never seen these wipers operate, but I presume the engine must be running given the vacuum controls. I’ve been following Willcox’s instructions. http://repairs.willcoxcorvette.com/w...-schematic.pdf
I manually opened the wiper door to do this testing. The wiper motor had been disconnected; I reconnected it.
Wiper Override Switch – Verify not overriding – It is turned clockwise (if I were lying on the floor facing UP at the switch). It’s not overriding the system.
Wiper Switch - Test for Ground – The dark blue wire is grounded; I used an ohmmeter to touch the dark blue wire and the shifter – it pegged the needle. The black wire is NOT grounded; doing the same ohmmeter test achieved no reading. I jumped the black wire to the transmission shifter to create a temporary ground. I started the car and turned the wipers on low and high. Nothing happened.
Wiper Motor Connector - Check the wires – They are in the correct positions
Main Harness - Check the wires (where the wiper motor connector connects) – They are correct. The red wire is hot when the engine is off. The black is a solid ground (using the ohmmeter, touching the ground and the spark plug wire chrome covers pegged the needle). I started the engine and tested the Brown wire for power; I received no reading. Is the Brown to provide power when the engine is running or if the wiper motor is running? Regardless, I got nothing.
Limit Switch – It works. I pulled the covering assembly off and tested it with button pushed. Full continuity.
Wiper Solenoid – How do you get to that and what is the test? Should I bother given what I’ve said above?
Switch Connector Installation – Properly oriented – bumps on female and male housings are on opposing ends.
Override Switch Ground – Black wire entering switch is a solid ground. Instructions say the ‘bracket’ should be grounded. Bridging the bracket as well as the nut connector to the shifter did NOT achieve a ground. Instructions say to ‘clip a ground to the side’ and touch to a known ground. Clip it to the side of what? And then do what?
Where to from here? I have a new motor in a box but don’t want to just drop it in to burn it up, too.
I think the 68 motor has 3 wires and the 69 and new are 2 wire. How many wires does your have. If 2 you may have to refer to a 69 diagram. This is just a guess.
DocRebuild's has a great electrical chart for your year 1968/ look up, OOSOEZ.COM for 68'
I highly recommend them as I'm rebuilding my 1970 and so far they have helped me a great deal for electrical identification and simplicity.
I believe 68 wiper motors are wired different that any other year. that probably why it has a 69 motor in it.
That said you must first do a motor test. follow the willcox instructions to see if that motor works. If it does then check all grounds, 68+69 motors must have a motor housing ground wire, and ground wires to the main on off switch HOUSING and to the speedometer tach and ignition switch housings. The ground wires must connect to the housings and not a terminal on the switch. do you follow me here.
The 3 wires on the motor and the back of the on off switch change functions depending on the switch position so checking for ground or continuity is a waist of time in my opinion.
There is a relay under the radio and console. follow the testing for this relay. this relay must also have a housing ground wire.
You see the pattern here, do the motor test first then check the ground at the on-off switch.
The shifter handle is not a good place to check your grounds, I use the
door latch POST in the door jam.
Some of the members here a very good at finding problems in wiring so hang in there.
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Stop!!! The 68 is definitely wired differntly than all others. It has a constant +12 looking for a ground. You need to order a 68 motor and start from there provided the wiring is still all 68. You will start frying wiring and components if you or at the minimum alot of fuses!!
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Is the new motor a 68 motor? When you get the 68 motor do the bench test that you'll find on the wilcox site. Take an ohm meter and check that the wiper door limit switch is 0 ohms when the switch is closed. Ill post the diagrams and links I have tonight. Theres a relay under your center console and a relay on the back of your tach. Hopefully the limit switch was turned off when the dealer started messing with it and everything else works. There is also a troubleshooting addendum in the aim which is very helpful. You will need to check the wiper switch housing for ground, you will have to remove the small housing around it, it has one screw going straight up. If you need a new wiper switch buy a used one. I got mine from 1960fi. His names George. Works better than a new chinese switch that broke the second time I turned on the wipers to test everything
Welcome to the joys of the 68!
Last edited by Rescue Rogers; Feb 17, 2017 at 07:55 AM.
Yes, the new motor is a rebuilt '68. I will do a bench test on it using the Willcox video. I'll also test the resistance of the wiper door limit switch (my understanding is that it should show continuity when the button is depressed and zero when not depressed) - I did this once, but I'll do it again. You mention the relays under the center console and on the back of the tach; should I test these before installing the new motor? If so, I presume I need to pull the center bezel / instruments and the tach bezel. Have you seen any instructions on how to do that? It seems I'll have to loosen or remove my shifter console to get the center bezel loose. I presume by your comments around the limit switch that I should make sure it is not depressed when and if I install the new wiper motor. Is that correct? You say I need to check the wiper switch housing for ground, requiring that I remove the small housing around it. I'm trying to understand that better. The switch housing is primarily a composite mounted to a metal bracket. The wiper switch mounts to the back of metal bezel with two screws. That metal bezel attaches above the center instrument bezel with three screws (one running vertical and two horizontal - my horizontal screws are missing). My understanding is that ALL of these connections are used to ground the switch. When you say "check the wiper switch housing for ground" are you saying remove the switch from the bezel and test the housing? Or are you saying remove the switch from the bezel and then disassemble the housing to reveal a ground point? or something else? If I am checking the grounding of the switch, doesn't it need to be attached to the point where it receives the ground? or am I verifying the ground coming from the wiring to the switch?
I've inserted a picture below to help. Sorry for my ignorance.
Some have suggested running a patch power and ground wire to the motor to test the existing motor in place. Rescue Rogers, are you saying this may result in frying some parts?
Just a couple of photos on my 1970, may help, may not:
Console wiper switch
Wiper actuator on tach 1970
This under the shift console
1970 <br/>I had to drop the steering column to ease out the dash. Disconnect the speed cable under the car and disconnect the tach cable so it allows you to gain access to disconnecting the cables from above (space for your hands is limited) press a small tab ( on both ) to then disconnect speed & tach from above. This allows space to disconnect electrical connections.
1970. To take apart the console you have to start at the emergency brake, remove ( I think I have a photo or Alan does ) the bolt 5/16" I believe located under the rear deck center compartment area.
Btw, undo screws on side of console(s) before this step.If you have power windows you have to lift (after removing rear bolt) the emergency console slowly and disconnect (two) PW connections and then slowly slide the console back from the center strip enclosing the brake lever, it will come off
If you look to the left on this picture just above the insulation on the wall you'll see a hole, that is the bolt that must be removed to start the sequence.<br/>Remember to set the parking brake also you'll have to remove the shift **** (keep in Park ) to remove the center console going forward.
I hope these help, you may find removing your drivers seat helps access the dash area better.
Also be very careful there are two tabs on the birdcage right to the left of the steering wheel,
THEY ARE EXTREMELY SHARP cover them with a piece of material (towel) and wrap tape on them, you'll be glad you did.
Speedometer/ See the small tab where the cable connects, this needs to be pressed to allow the cable to release. Also the black straps need to be straightened to relieve the harness.
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Originally Posted by NRAROX
Yes, the new motor is a rebuilt '68. I will do a bench test on it using the Willcox video. I'll also test the resistance of the wiper door limit switch (my understanding is that it should show continuity when the button is depressed and zero when not depressed) - I did this once, but I'll do it again. You mention the relays under the center console and on the back of the tach; should I test these before installing the new motor? If so, I presume I need to pull the center bezel / instruments and the tach bezel. Have you seen any instructions on how to do that? It seems I'll have to loosen or remove my shifter console to get the center bezel loose. I presume by your comments around the limit switch that I should make sure it is not depressed when and if I install the new wiper motor. Is that correct? You say I need to check the wiper switch housing for ground, requiring that I remove the small housing around it. I'm trying to understand that better. The switch housing is primarily a composite mounted to a metal bracket. The wiper switch mounts to the back of metal bezel with two screws. That metal bezel attaches above the center instrument bezel with three screws (one running vertical and two horizontal - my horizontal screws are missing). My understanding is that ALL of these connections are used to ground the switch. When you say "check the wiper switch housing for ground" are you saying remove the switch from the bezel and test the housing? Or are you saying remove the switch from the bezel and then disassemble the housing to reveal a ground point? or something else? If I am checking the grounding of the switch, doesn't it need to be attached to the point where it receives the ground? or am I verifying the ground coming from the wiring to the switch?
I've inserted a picture below to help. Sorry for my ignorance.
Some have suggested running a patch power and ground wire to the motor to test the existing motor in place. Rescue Rogers, are you saying this may result in frying some parts?
Connecting the wrong motor to your system would cause some serious problems for it, connecting your rebuilt 68 motor wont hurt the motor if the wiring is still connected properly and hasnt been messed with.
Disconnect the battery when you install the motor and you wont have to worry about shorting anything or it turning on when it shouldnt. Dont connect the wiper transmission so the motor will just run. It may not park once it gets running with out the transmission connected but you want to get it running first.
Dont pull the dash just yet. The solenoid on the tach is for the door operation. If the door doesnt open you can manually open it and troubleshoot that later.
The switch when not depressed will read HIgh resistance because its open, depressed it will read 0, dead short across. there should be a wire coming up from your heater motor to the wiper motor. Thats the first ground
I would install the motor after the bench test and see what works. turn the wiper service switch both ways after each test to make sure its not in the open position. You can test the service switch to see when it grounds and put a white dot where you can see it. and the dot would be the on position. The wiper door should operate and then the motor will start once the limit switch if fully depressed. This gives the motor 1 of its grounds. Ground #2
If it doesnt start, check the limit switch. You may need to adjust the door actuator to get the plunger to fully depress if the previous owner messed with it.
If it still doesnt work attach a new ground from the switch housing to the birdcage behind the dash. The switch housing grounds to the metal cover which grounds on the center console, but if its cracked the ground can be comprimised. Its just better to run a wire from where the screws hold the switch housing to the metal cover to the frame. You should be able to connect the wire there and either reach through the opening or take off the passenger side dash and find a suitable bolt to attach a clamp to. You can run a test wire from the switch to test the motor at this point,but the switch must be grounded to get the system to work, ground number 3. In the switch diagram link you can see how the switch grounds the wiring for the motor speeds.
If it still doesnt work I would take the shift housing off of the center console and look and see if you can see the relay. you can pull the side radio access panel on the left side and see if that helps. IF neither give you reasonable access you will need to pull the passenger side dash off. Not super necessary but it make it easdier to get everything back together. pull the center gauge console out. You can take out the side screws but the hard part is getting the 2 studs at the bottom center. They are what attaches the gauge console to the center console. You may not have to disconnect everything from the gauges, it may lay down flat on the center console, just lay a towel between the 2 to keep anything from getting scratched. Once thats disconnected you can unscrew the 4 screws holding the center console down. You should be able to lift it just enough without disconnecting the vent and heating controls to look under it for the relay. Its bolted to the floor at the front. I didnt bother testing mine, it looked original so I just replaced it. I think both that and the solenoid on the tach were cheap and I just replaced both because of all the work to get at them. You might be able to lay on your floor and see up under the dash enough to see the tach solenoid. If you take out the seats it makes it easier to get under the dash.
Okay. I think I'll start by pulling the existing motor and bench testing IT to make sure the problem isn't elsewhere. Thanks much and thanks for the link.
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Originally Posted by NRAROX
Okay. I think I'll start by pulling the existing motor and bench testing IT to make sure the problem isn't elsewhere. Thanks much and thanks for the link.
I've been updating my post. please re read it. I've been adding to it.
You can test the motor, if its 69+ you might as well sell it or give it away when your done. The 68 motor is what you should be bench testing then installing. The 68 has many different grounds. The motor housing is grounded, but the motor it self is live as soon as the key is on. It won't work until the wiring is provided a ground through the limit switch to the service switch to ground on an early 68. Its the old school rotary switch that needs to have a good ground as well. The wiper switch is live and the switch positions provide the ground through the housing. No wires on it go to ground directly. It isnt designed to be opened. The relay has its own grounding wire.
Last edited by Rescue Rogers; Feb 17, 2017 at 09:15 PM.
'Very helpful guys. Many thanks. Two open questions:
Grounding the Dash Service Switch - Since the dash service switch creates a ground via it's bezel, is this switch grounded when it is detached from this bezel (as it might be found in testing)? One wouldn't think so. I'm trying to understand what has to be tested 'in place' if one is trying to understand what is really going on in the system.
Override Switch Ground – Willcox instructions say the ‘bracket’ should be grounded. In testing I cannot detect that the bracket or the nut connector is grounded. It appears that where this override switch is attached the material is nylon or plastic. How could it ever achieve a ground? Could this be part of the problem?
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Originally Posted by NRAROX
'Very helpful guys. Many thanks. Two open questions:
Grounding the Dash Service Switch - Since the dash service switch creates a ground via it's bezel, is this switch grounded when it is detached from this bezel (as it might be found in testing)? One wouldn't think so. I'm trying to understand what has to be tested 'in place' if one is trying to understand what is really going on in the system.
Override Switch Ground – Willcox instructions say the ‘bracket’ should be grounded. In testing I cannot detect that the bracket or the nut connector is grounded. It appears that where this override switch is attached the material is nylon or plastic. How could it ever. achieve a ground? Could this be part of the problem?
Yes, if the single wire switch is not connected to the frame it will not function, you can test it for short from the wire connector to the case. If its still mounted, check from the wire connector to the frame
post a pic of which switch you have. the early switch grounded to the frame and the later one didnt. You need to make sure it is grounded. If left in bypass it will kill your battery so mark the on position with a white paint pen.
when was your car produced, post the vin or look it up so we know if its early or late production
Last edited by Rescue Rogers; Feb 18, 2017 at 02:52 PM.
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heres some pics of what it shpould look like for an early 68
early 68 bracket and over ride switch and maintenance switches rotary switch with ground in upper right corner case ground that goes to heater blower ground washer wiring and plugs
The wipers are working. I performed some more tests patching in a ground in a couple places without success. I went to pull the wiper motor and found a harness cable disconnected. I also found a loose ground wire on the motor itself. I reattached the harness and tightened the ground. I patched a ground from the dash switch to the 'door open' button in the door hinge. Turned on the key and 'BAM'. They ran.
I found that with the override switch on (to stop the wipers) and the ignition key off, a small spark occurs when the wiper dash switch housing is grounded to the instrument housing. I presume that is that small power drain that everyone refers to as caused by the override switch. Correct? Hopefully something else isn't going on.
I'll bench test my new '68 motor soon and then swap it in. For now, I have wipers.
Now I need to figure out how to properly mount the dash switch bezel, the bezel beneath that, and the horizontal air vent that fits between them. I'll shoot a few pictures and post something soon.
My car was built in December 1967, Rescue. My override switch panel is configured differently. It has the two vacuum overrides on each side and the wiper override in the middle position.
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Congratulations. I hope it keeps running. Does the wiper door work and the headlights open? That would be the next fun and exciting problem to solve. Hopefully everything is working for you
1968 Wiper Troubleshooting
