2005 GMC Yukon 5.3L - Rear Wiper Motor Intermittently Not Working
Affiliate Disclosure: As an Amazon Associate, we may earn commissions from qualifying purchases from Amazon.com.
General Information:
Customer came to the shop with a complaint that the rear wiper blade was not working. The customer says they do not use it often, but it works when they do use it. They also said that before it stopped working completely, it went crazy on them and would not turn off until they pulled the fuse. After replacing the fuse, that’s when it would not work again.
First Thoughts:
It’s an old vehicle, more than likely the rear wiper motor has gone bad, right? It’s not uncommon for older parts that rarely get used to go bad. In this case, my mind went to the motor shorted out internally causing it to not turn off, then finally give up when the fused was pulled out then returned.
Diagnostics:
I decided to make sure the rear wiper motor was getting correct readings at the plug before calling it a bad motor and I’m glad I did.
All of the readings were correct, except for one.
The connector for the rear wiper motor has five wires. ( The list is in random order)
Power
Ground
Signal from the switch
Door Ajar Signal (The wiper motor doesn’t work when the door is open.)
Signal for the washer fluid
I checked to see if the motor was getting power, and it had the correct reading. I check to see if there was a signal from the switch that turns the wipers on and off and there was a reading*.
* I did not know what the correct voltage was on the signal wire. I just assumed that it was correct since there was a voltage that change when I turn the switch from on to low to high.
I had a reading for the door ajar wire and I had a reading for the washer fluid wire.
What I thought was weird is that on the ground wire, I was reading around 1 volt instead of having a ground. When I unplugged the connector to the rear wiper motor, it jumped up to 12 volts. I knew then that my problem was not with the motor, but a circuit issue.
The Yukon has a bad ground. Done? Kinda. I had to chase down the bad ground.
The easiest thing to do is to find a wiring diagram and figure out where the ground starts. The wiring diagram led to the right rear quarter panel. There I found the ground’s starting point and a splice where the ground splits off to different components.
I took a voltage measurement at the starting point of the ground and found it actually had a ground. Next, I took a measurement at each wire after the splice. Each wire at the splice had a ground. At that point, I knew there had to be a bad connection somewhere. I chased the ground wire, took multiple voltage readings and found a connector at the crease of the rear door and body of the car.
On one side of the connector, it had a ground, and on the other side, it had voltage. I found my problem. I opened the connector and there it was, corrosion right on the pin for the ground.
Why did this happen? I’m not really sure. There were spots where you can see that rain water had been running close to the plug for a while. It probably got into the plug and caused the corrosion.
How should you fix it? There are different ways to fix it. You could bypass the connector, buy a new connector, or buy a connector rebuild kit and put new terminals in the place of the bad ones. Luckily, this connector has empty spaces where you could put new terminals in, instead of using the corroded space. I would also try to seal the space that was leaking water, so this did not happen again. It probably just needs new weatherstripping.
End the end, this didn’t take took much time to diagnose, and the customer did not have to pay for a part they did not need.
Proper diagnostics can save time and money for you and the customer.
Disclaimer and Disclosure:
Due to factors beyond the control of DiagnosticMechanic.com, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. DiagnosticMechanic.com assumes no liability for property damage or injury incurred as a result of any of the information contained in this website. DiagnosticMechanic.com recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this website. Due to factors beyond the control of DiagnosticMechanic.com, no information contained in this website shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this website is the sole responsibility of the user and not DiagnosticMechanic.com.
DiagnosticMechanic.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. In many of our case studies, articles, and tool reviews, we may earn a small commission when readers purchase products through our links.