2004 Yukon power seat will not move forward

[ta6point6litre]

So I just bought a 2004 GMC Yukon Denali and one of the many little things I need to fix is the front drivers side power seat. All the other power seat functions seem to work except I cannot move the seat forward. I originally thought it might be the switch. If I disconnect the harness for the motor and apply voltage with my power probe the seat does move forward and backwards, so I know the motor works. I tried another switch but it did not make a difference. Any ideas?

 

[ivin74]

Did you buy the switch new or used?

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of folks here with deep experience on these trucks, and they will chime in with suggestions and perspectives.

When you directly connected power to the motor, bypassing the wiring harness, did you apply both a 12v connection and a ground connection to the motor? I'm asking, because disconnected or poorly connected ground wires can create issues, and you want to make sure that you have both a good 12v power connection and a good ground connection to the motor. Perhaps, the ground connection through the harness has an issue with it. (or perhaps, the motor is directly connected to ground through its housing, but I doubt it.)

 

[OR VietVet]

Welcome to the Forum from NH.

Lots of folks here with deep experience on these trucks, and they will chime in with suggestions and perspectives.

When you directly connected power to the motor, bypassing the wiring harness, did you apply both a 12v connection and a ground connection to the motor? I'm asking, because disconnected or poorly connected ground wires can create issues, and you want to make sure that you have both a good 12v power connection and a good ground connection to the motor. Perhaps, the ground connection through the harness has an issue with it. (or perhaps, the motor is directly connected to ground through it housing, but I doubt it.)

Good call, Joseph.

 

[ta6point6litre]

Did you buy the switch new or used?

The switch was from eBay and it was used.

 

[ta6point6litre]

Welcome to the Forum from NH.

Lots of folks here with deep experience on these trucks, and they will chime in with suggestions and perspectives.

When you directly connected power to the motor, bypassing the wiring harness, did you apply both a 12v connection and a ground connection to the motor? I'm asking, because disconnected or poorly connected ground wires can create issues, and you want to make sure that you have both a good 12v power connection and a good ground connection to the motor. Perhaps, the ground connection through the harness has an issue with it. (or perhaps, the motor is directly connected to ground through its housing, but I doubt it.)

Actually, at first the power seat on the driver side did not work at all. I did some online research and found a bunch of people saying the main harness under the seat can cause this problem. I unplugged it and did see some corrosion on the ground pin. After I plugged it back in everything worked except the seat forward control.

 

[OR VietVet]

May need to clean the connector or replace connector.

https://www.rockauto.com/en/moreinfo.php?pk=1929912&cc=1425327&jsn=2346

https://www.rockauto.com/en/moreinfo.php?pk=82553&cc=1425327&jsn=2347

https://www.rockauto.com/en/moreinfo.php?pk=1217580&cc=1425327&jsn=2349

 

[ta6point6litre]

Figured it out. Before I unplugged the main harness under the seat I had removed the power seat module from the plastic case. I did not realize the 2 plugs that connect from underneath were not completely pushed all the way back in because they are pretty hard to see. Now everything is working properly.

 

[OR VietVet]

Basics win again. I would lose track of how many times we here have told posters to recheck any recent work done in the area of the current problem.

 

[Joseph Garcia]

Thank you for reporting back with the results of your issue resolution. Very much appreciated.

We have added to the knowledge base (watch out for these two hard-to-see connectors when working on seat electrical systems), and re-affirmed best troubleshooting practices (re-look at any recently performed work, to see if it is somehow related the current issue).