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Discussion Starter · #1 ·
John, Guys

I'm finally starting to reassemble my 72 and have two current electrical problems. Well actually several but I'll start with these. First, I think my wiper/washer motor may be shorted out. When I turn on the ignition it starts running on low speed in both the off and low speed setting. When I turn it to high speed it runs on high. Also, if I connect the wires to the washer terminals the washer runs constantly. Using my multi meter I found that I have continuity between all leads and between the leads and the motor housing. I assume this means that there is a short inside the unit.

Secound, I assume my front (head light) harness must have been modified by someone even though it is in pretty good shape because it is different than the wiring diagram. On the diagram the running/side marker lights have a power wire in and then they connect to a brown wire which appears to be connected to a series of wires that connect to the brown wire on the head light connector and runs back through the firewall connector. Mine are different, mine have a power wire that comes into the marker light and other side has a connector on it that was grounded out to the rad support. Should I leave it that way or should I splice it back into the brown wire at the headlight socket?

Thanks in advance.

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72 Chevelle and a 70 Chevelle with a crushed roof
ACES # 4051 MCC # 448
TC # 1549 81/70 Cruisers
 

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If it's the same in 72 as it was in '68 and '77, the wiper motor is switched via ground. When both terminals are grounded, you get low speed. When only one terminal is grounded you get high speed. I think your trouble is in your switch.

Disconnect the wiring and ohm the switch in each different position. I think you'll find the problem.

As far as your lamp harness is concerned, if it works reliably and isn't ugly, leave it alone. If you're all for originality, then change it back.

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'68 El Camino, 357, L31 Vortec heads, 700R4,
8.2 10-bolt, 3.55 gears, Auburn Pro Posi.

[This message has been edited by cjlandry (edited 07-21-2002).]
 

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Rick
Chad's right about the ground controlling the wiper. Sent a couple of things to your email including a picture of the 72 wiper switch. Labeled the contacts as to which was which. That should help you figure out if it's the switch or not.
 

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Discussion Starter · #4 ·
Thanks Guys/John

the switch is fine, if I remove the unit and use my meter to ohm the three connector posts on the wiper unit I have continuity between them. I have another old motor that is burned out and I checked the same three leads on it and there is no continuity between the three. Don't know if that is because that motor is cooked or not. I can get a rebuilt unit from advanced auto for about $50 so I think I'll swap it out and see what happens.

I have so many under dash electrical gremlims I'm not going to waste a lot of time on this motor.

thanks again

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72 Chevelle and a 70 Chevelle with a crushed roof
ACES # 4051 MCC # 448
TC # 1549 81/70 Cruisers
 

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You're supposed to have continuity between the three terminals. You're reading across the windings.

The one that shows no continuity is burned because the windings are open.

Don't buy a wiper motor. Yours is good and you can't return electrical parts for a refund.

I'll post a little later how to test your motor after I check which terminal is hot.

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My Web Page (updated 06-21-02)

"Long Live Freedom!"

Chad Landry
TC Member #643
ACES Member #4556
'68 El Camino, 357, L31 Vortec heads, 700R4,
8.2 10-bolt, 3.55 gears, Auburn Pro Posi.
 

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Discussion Starter · #6 ·
Ok, thanks

Did I neglect to mention that if I test ohms between the terminals and the housing of the motor I also have continuity. That is why I thought it was shorted out. If I have a reading between the terminals is it shorted out to the housing, therefore getting it's ground at all times via the ground strap to the firewall.

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72 Chevelle and a 70 Chevelle with a crushed roof
ACES # 4051 MCC # 448
TC # 1549 81/70 Cruisers

[This message has been edited by Professor_SS (edited 07-22-2002).]
 

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The only thing that puzzles me is that you get low speed when the key is on, but it goes to high speed when you switch it to high speed. It has to drop ground from one terminal to go high speed.

Turn the key on and find which terminal gets 12 volts. Disconnect the other two terminals and see if it stops. If not, you probably do have an internal ground.

But you should check the park circuit. This is a major PITA and all I can tell you about it is that you have to pull the washer assembly to see how all that works. It's not fun. I can't begin to describe the operation with text.

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My Web Page (updated 06-21-02)

"Long Live Freedom!"

Chad Landry
TC Member #643
ACES Member #4556
'68 El Camino, 357, L31 Vortec heads, 700R4,
8.2 10-bolt, 3.55 gears, Auburn Pro Posi.
 

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Discussion Starter · #9 ·
Ok guys, after having some time to talk to the kid, and play with this I have the following

1. I found out that my boy who helped dad by cleaning up the wiper motor/washer unit a few months ago soaked it in the parts cleaner, I thought I smelled kero.

2. I broke a plastic post off on the wiper switch and removed the switch to do some repairs, which of the three screws does the black wire with the eye on it go? I may have put it under the wrong one? maybe I grounded the switch because if I ohm the the leads (the three main leads to the motor section of the wiper) I have one that has power, but both have a ohm reading to ground on the other two with key on no matter where the switch is set (off, low, high) but it I have no continuity if the switch is off.

3. I still have continuity between all three terminals on the motor and the motor housing, still think there must be an internal short in the motor....

4. I hate car wiring... give me a small block to tear down any day cmpared to running this stuff to ground (pun intended)!

as always thanks

rick

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72 Chevelle and a 70 Chevelle with a crushed roof
ACES # 4051 MCC # 448
TC # 1549 81/70 Cruisers
 

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Discussion Starter · #10 ·
sorry hit the wrong thing and quoted instead of edited... I'm going to have a stiff drink now and go hide in the garage for awhile before a lightening bolt hits me or a christmas dwarf attacks me!!!

*Edit*
Ya know Rick, I should have deleted all of this for you but just like to point out one thing. You sure have a problem with dwarfs.

[This message has been edited by John_Muha (edited 07-24-2002).]
 

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The black ground wire should function correctly reguardless of which wiper switch mounting screw it is attached to.

This may help.

68-72 hideaway wiper circuit. CLICK FOR DRAWING
1. Wiper switch. (grounds the three attached wires as follows)
Light Blue- grounded in Low-speed and Hi-speed positions.
Black- grounded in Low-speed and Off positions.
Dark Blue- grounded when pushed for washer pump operation.

2. Run solenoid. The Light Blue wire is grounded to lock out the park (mechanically prevents the wipers from being driven to the park position) and close the run/park switch.

3. Shunt winding. This winding is parallel to the armature winding.


4. Series winding. This winding is in series with the armature and shunt windings.

5. Run/Park switch. Closed when the run solenoid is energized (Light Blue wire grounded) or when the run solenoid is de-energized and wipers are not in park position.


6. Wash pump start coil. When the Dark Blue wire is grounded this coil latches the wash pump for one cycle.

7. Shunt winding resistor. Grounds the shunt winding during high-speed operation, bypassed (Black wire grounded) during low-speed and park.


8. Wiper motor fuse (25 amp) in fuse block. Has +12 VDC when ignition switch is in run or accessory position.


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