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DTC codes P0974 and P0700

Tiny
AGGIE826
  • MEMBER
  • 2008 GMC SIERRA
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 11,500 MILES
Truck starts and seems to run okay; I am afraid to take out on a long drive and ruin transmission. I erased the codes, but they went out and came right back without driving the truck. I need a wiring diagram that will help me to trouble shoot the circuit for transmission solenoids. Does the truck need to run through a drive cycle to erase the code? Vehicle VIN 1GTEK14J08Z302940. Where is the TCM located on this truck? Before this happened, the truck would not engage the 4-wheel drive so I drove it in 2-wheel drive because I could not find the problem to fix the 4-wheel drive not engaging. Please help me solve this problem. 115,000 miles
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Wednesday, June 22nd, 2022 AT 5:15 AM

7 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,772 POSTS
Hi,

I would be happy to help. I need some clarification. First, as you are likely aware, the P0700 is a generic code that simply means there is a code stored in the transmission control module (TCM). The code that is of interest is the P0974. However, I need to know which model transmission you have to proceed.

If you look at pic 1 below, it shows the options that were available on your truck. Pics 2 and 3 show where and how to identify the transmission type. This is what I need.

Let me know so I know which direction to go.

Take care,

Joe

See pics below.
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Wednesday, June 22nd, 2022 AT 4:48 PM
Tiny
AGGIE826
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  • 18 POSTS
I believe it's the 4L60E could not find the identification plate.
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Friday, June 24th, 2022 AT 4:39 AM
Tiny
AGGIE826
  • MEMBER
  • 18 POSTS
Please help, thank you for responding.
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Friday, June 24th, 2022 AT 4:43 AM
Tiny
AGGIE826
  • MEMBER
  • 18 POSTS
It's 2008 Sierra engine 5.3, 4-wheel drive Z71with a tow package.
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Friday, June 24th, 2022 AT 7:25 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,772 POSTS
Hi,

I copied one of your pics and circled the shift linkage. Does the vehicle go into gear at all? The linkage is disconnected. See pic 1 below.

As far as the code, it indicates there is excessive voltage with the 1-2 shift solenoid. It could be shorted.

Pics 2 and 3 are the diagnostics for the code. Pic 4 is the wiring schematic for the shift circuits. Pic 5 shows the 1-2 shift solenoid location in the transmission, and the last pic shows the location of the TCM. It is right below the battery on the driver's side.

Check the wiring to the TCM. I've seen battery acid cause damage, so that could be an issue.

Let me know what you find.

Joe

See pics below.
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Friday, June 24th, 2022 AT 8:07 PM
Tiny
AGGIE826
  • MEMBER
  • 18 POSTS
The information you sent was very good just that I am a DYI and don't have a fancy scanner to help me diagnose the problem. I was able to remove the transmission oil pan to get to the shift solenoids. Using a 9-volt battery I was able to test the solenoid and one of them was not clicking at all. The other two were. The bad one tested bad for resistance. I replaced the tree shift solenoids, new filter and oil. Erased the DTC codes and now I have no codes. Previously I could not erase the P0974 code. I have not driven the truck yet because while I have the truck lifted on the stands, I am hoping you can help me with the four-wheel drive not engaging. I previously removed the actuator that engages the front wheel drive and tested it with 12 volts from the battery and the plunger does activate. I also replaced the transfer case motor and no difference. I also changed the transfer case module with another used one and nothing changed. Now the 4-wheel drive control selector is on Auto. I can move the selector all the way to Neutral and all the lights on selector light up including the neutral light. Can you please help?
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Monday, June 27th, 2022 AT 8:53 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,772 POSTS
Hi,

It sounds like you found the issue without the scanner. Excellent job. As far as the 4wd, I would be happy to help but I have to ask a favor. I need you to simply copy and paste the 4wd question to a new thread. We try to keep the threads specific to one topic so that it is more helpful to others. I hope you understand.

Here is the link to start a new thread. Again, I truly hope you understand.

Take care and I'll watch for your new post.

Joe
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Monday, June 27th, 2022 AT 8:11 PM

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