Seat not working?

Tiny
JERVAIS
  • MEMBER
  • 2008 GMC YUKON
  • V8
  • 2WD
  • AUTOMATIC
  • 105,000 MILES
My driver seat does not work all of the time. Sometimes It goes into exit seating mode (slides all the way back) but then it will not work when I try to move it back up. Sometimes it works, sometimes it does not. What could that be?
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Wednesday, July 6th, 2016 AT 8:17 PM

36 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
If this vehicle has had the air bag deployed then the seat module must be reprogrammed because there is a code stuck in memory. check around parking brake where harnesses are and see if any are chafed or cut that may be a problem. finally scan for codes as it may show a code. Here is a guide to help us with the CAN scan

https://youtu.be/InIlnsjOVFA

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.
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Thursday, July 7th, 2016 AT 6:13 AM
Tiny
CHRIS EMERY
  • MEMBER
  • 10 POSTS
  • 2007 GMC YUKON
  • 6.2L
  • V8
  • AWD
  • AUTOMATIC
  • 151,000 MILES
I have read the posts here about this problem. Driver power not working. Adjustable pedals not working. I have pulled off the power seat switch and there is some power to the switch.
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
  • 33,699 POSTS
What does "some power" mean? Check the red wire to the power seat switch. It should have 12 volts all the time. To be most accurate, that should be measured by back-probing the wire with the connector plugged in. Alternately, a test light works better for this test, but if all you have is a digital voltmeter, that will be okay too.
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
CHRIS EMERY
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  • 10 POSTS
Red does have power. What I meant by "some power" was there was not any power to any of the other wires, just the one.
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
CARADIODOC
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Dandy. Now the potential problem is there can be a break in the wire with just one tiny strand left, and that is enough for a digital meter to detect 12 volts, but it's not sufficient to pass the amount of current needed to run a motor. If you tested the wire with a test light, those draw more current and we can believe it. To be safe, and to insure we are not glossing over a clue, test that wire while the switch is plugged in and you activate one of those switches. Either that 12 volts is going to stay there, or it is going to drop close to 0 volts. If it drops to 0 volts, we have to treat that red wire as not having 12 volts. This may seem like overkill, but it is exactly the type of mistake that sends experts down the wrong path.

There are actually 12 switch contacts built into the driver's seat switch assembly, and we know they did not all fail at the same time. Also, there are three motors, and they also did not fail at the same time. That only leaves the ground circuit as the source of the defect. We can use any of the three circuits for testing. I am going to pick the forward/backward switch, just so I can tell you which wires to probe. These next tests must be done with the switch plugged in.

Back-probe the tan and the light green wires. Both will have 0 volts when the switch is released. Now, while watching one of those wires, move the switch in one direction, then the other direction. In one of those directions you should find 12 volts on the tan wire, and 0 volts on the light green wire. In the other direction, you should find 12 volts on the light green wire and 0 volts on the tan wire. If you find 12 volts on both wires at the same time, regardless of which way you push the switch, the ground wire has a break. If that is what you find, measure the voltage on the black wire while the switch is pressed and you have that 12 volts on the tan and light green wires. If you find 12 volts on the black wire, there is a break in that wire or where the wire is bolted to the body, near the base of the left "B" pillar. If you find 0 volts on the black wire, either there is break inside the switch, (very uncommon), or that terminal is not making good contact.
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
CHRIS EMERY
  • MEMBER
  • 10 POSTS
  • 2007 GMC YUKON
  • 6.2L
  • V8
  • AWD
  • AUTOMATIC
  • 151,000 MILES
Driver's power seat, adjustable pedals not working.
When you push memory seats positions, mirrors will adjust, but the seat or pedals do not. I have power at the seat switch.
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
CHRIS EMERY
  • MEMBER
  • 10 POSTS
12+ volts on the tan wire when switch pushed forward. 12+ volts on the green wire when pushed to the rear. 0 on both when idle.
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check routing of harness under seat as that has been a problem on earlier models also check for good connection at switch. You may have to take that area off to check it the pedal ground is non HVAC on right hand side see if it is a good connection. Finally have a mechanic scan for codes. One other thing check grounds on engine for no corrosion's. I have also included a tip which others have found see picture.
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
CHRIS EMERY
  • MEMBER
  • 10 POSTS
Seat Switch plug
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
CARADIODOC
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What did you find on both wires when the switch was pressed one way? If you found 12 volts on both at the same time, you should have also found 12 volts on the black wire. Check that black wire. If you see any voltage, even if it's less than 12 volts, (but not 0 volts), there is a break in that black wire.
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
CHRIS EMERY
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  • 10 POSTS
The current alternated between the two seat switch positions when activated. When you say black wire, do you mean the gray with black
Stripe. When I connect the purple + and gray /black (-) I get 12+. Is this correct in what you asking?
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
CARADIODOC
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There's no purple wire on my diagram. I suppose there could be a white tracer on the black wire, but that isn't shown on my diagram.

To double-check, your test light clip lead or meter negative probe should be on ground, meaning a paint-free point on the body. This way we're taking voltage readings AT a point in the circuit, as opposed to between two points. Those are just two different ways of doing this, but we have to be sure we're both doing it the same way.

Measure the voltage on your black / white wire while you activate the switches. Do you see anything other than 0 volts at any time?
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
TOMMII
  • MEMBER
  • 2 POSTS
  • 2007 GMC YUKON
  • 5.0L
  • V8
  • 4WD
  • AUTOMATIC
  • 80,000 MILES
Drive side power seat just stopped working and is locked in a position for wife who is shorter than me
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
Do you hear the motor trying to run when you pull the switch? Check fuses.
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
CHRIS EMERY
  • MEMBER
  • 10 POSTS
Just checking, did you get the picture I attached of the power seat plug showing the wire colors? Just want to make sure I'm working in the right spot.
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
TOMMII
  • MEMBER
  • 2 POSTS
The motor does not run. Reading the manaul the dsm fuse operates the seat and remote start. The remote start still works but I will check the fuse
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
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I see eight wires in it, which is correct. Check where the wires go to. The wires must go to the three motors under the seat. There is another version that is for heated / climate-controlled seats. I don't know how many wires are in that plug.
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
JOHNNYT73
  • MECHANIC
  • 924 POSTS
IF you can get to the connector for the motor under the seat. Get a test light and see if when you pull the switch that you are getting power to the motor.
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
CHRIS EMERY
  • MEMBER
  • 10 POSTS
Ok, Here is the results,

with - line grounded on frame and using the + tip to check current at each wire.
With each switch activated individually.(8 positions)

Purple - Hot

Tan - Seat forward 12+
Lt Grn - Seat back 12+

Grn/Wht - Seat back Recline 12+
Gray/Blk - Seat back forward 12+

Yellow - Seat bottom back up 12+
Lt Blue - Seat bottom back down 12+

Dk Blue - Seat bottom front down 12+
Dk Green - Seat bottom front up 12+

I also noticed that when activating a switch and "holding" that position, not only did that corresponding
wire show 12+, but all other positions showed 10.7 volts at the same time. Apparently, no ground at the switch?
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
  • 33,699 POSTS
Yup. Without going back to the diagram, if you have 12 volts on multiple wires when a switch is activated, you're missing the ground. As I recall, the ground wire is bolted to the "B" pillar next to the driver's seat. I suspect you'll have to pop off a plastic trim cover and / or pull up the carpet.

A better way to verify this, without even having to worry about wire colors, is to measure the voltage across the two wires right at a motor's connector. If you're finding 10.7 volts on the ground wire, you're going to find the remainder of the 12 volts across the motor. That will be less than two and a half volts, which is not enough to make a motor run.
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Tuesday, September 3rd, 2019 AT 6:25 PM (Merged)

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