Best way to test wiper motor?

MoparMuscleMan440

Active Member
Joined
Jun 9, 2021
Messages
28
Reaction score
13
Location
Butler, Pa.
I now am having an issue with my wipers not working on my '87 Fifth Ave. I checked the fuse in the block, and it's fine. I know there are lots of things it could be,( ie; switch, motor, wiring,etc.), so I think I would like to start with the motor itself. Since there is a 4 conductor plug that goes to it, and a 4 or 5 conductor jumper block of some sort below it, ( I assume is tied to the intermittent circuit ), I would like to connect a hot and a ground to the terminals, just to see if the problem is in the motor, or somewhere else. So, to be brief, am I to assume that the red on that connector is 12v+, and the black is the ground? I can't find a wiring diagram that is clear on this. Anyone got an easy way of testing motor without removing it from the car? I want to be sure that I connect power to this puppy the correct way, so as not to accidently burn it up.Thanks.
 

Aspen500

Well-Known Member
Joined
Feb 14, 2015
Messages
7,148
Reaction score
2,854
Location
Rib Mountain, WI
May sound silly and cave man like but, with the switch turned on, smack the motor (not TOO hard) as a quick check, and see if anything happens. Many times at work, when the complaint is wipers or heater fan inop, we'll smack it first before getting out the wiring diagram and DVOM (and now days, hook up the scanner too). More often than not, it starts working. Of course, we replace the part then. Same method can work on an alternator or starter. If the brushes are worn, they may stick, and smacking it knocks them loose so they contact the commutator. If it doesn't make a difference, then we do a proper diagnosis.
 

MoparMuscleMan440

Active Member
Joined
Jun 9, 2021
Messages
28
Reaction score
13
Location
Butler, Pa.
Got the problem taken care of. Seems that the tab on the one securement or mounting stud that is used for the ground, suddenly wasn't making the ground contact, due, I suppose, to a light rust coating that developed over time. I attached a grounding wire, and viola, working once again! Wish my lighting problems were that easy to tackle, but one step at a time, I guess. Anyway, thanks for the input.
 

LSM360

Well-Known Member
Joined
Nov 28, 2011
Messages
838
Reaction score
331
Location
Melbourne, Florida
Got the problem taken care of. Seems that the tab on the one securement or mounting stud that is used for the ground, suddenly wasn't making the ground contact, due, I suppose, to a light rust coating that developed over time. I attached a grounding wire, and viola, working once again! Wish my lighting problems were that easy to tackle, but one step at a time, I guess. Anyway, thanks for the input.
If it's easy enough, would you post a pic of where you attached grounding wire? I think mine has same issue. I was thinking of tack welding a wire to body of motor and attaching other end to fire wall???
 

MoparMuscleMan440

Active Member
Joined
Jun 9, 2021
Messages
28
Reaction score
13
Location
Butler, Pa.
Sorry I didn't see your post sooner, LSM , or I would have gotten back to you about your wiper problem right away. Been pretty busy. Well, I can tell you exactly what I did to correct it, without a pic, it's pretty simple. I simply made up a wire with a blue open face crimp connector attatched to each end, fastened one end under the head of the retaining screw that holds the metal motor housing of the wiper motor in place, and, in this case, fastened the other end under the head of the bolt of the starter relay for a good ground contact. I soldered the wires to the crimp connectors, just to be on the safe side. Just make sure the wire you use, is going to be long enough to reach your targeted grounding point. I used a length of 16 gauge speaker wire, but whatever you have on hand will do. You can also use the reinforcing bars for the engine bay, as your grounding point, since it's a little closer to the wiper motor. I used the starter relay instead, it just seemed easier at the time. I would advise against tack welding a wire to the body of the wiper motor, ..... could burn a hole through the body of the unit and ruin your motor. That's pretty thin gauge metal. Also, that kind of heat, wouldn't do it any good either.
 

Mikes5thAve

Well-Known Member
Joined
Mar 3, 2020
Messages
1,501
Reaction score
609
Location
Canada
I was going to say, that grounding had been the only problem I ever had.
On mine I ran a wire to an existing screw on the motor. The rubber mounts stop it from getting a perfect ground through the studs which is what thst little ground tab tries to get around.
 
Back
Top