2004 Base model p2120 and p2121
Thread Starter
Cruising
Joined: Apr 2023
Posts: 11
Likes: 0
2004 Base model p2120 and p2121
Heya
have a 2004 c5. Been getting codes on and off for a bit, been trying to track it down.
First thing I ended up seeing as a slow pedal on the graph compared to the throttle position sensor. Bought the kit that gives you a different harness and lets you run a different pedal sensor.
dropped a couple of the codes, 2131 and 2126
still was getting the 2120 and 21 putting me in limp mode randomly.
Replaced the throttle position sensor. Didn't seem to help. When it runs, it seems to skip at certain rpm after I get on it.
I pulled the throttle body off tonight. Doesn't seem to have damage to the butterfly that I can see. It moves ok, when I release it though it goes down and bounces off the bottom. I haven't noticed that on other cars I've worked on - but haven't had to mess with a GM drive by wire throttle body
Any direction to look at this point might be helpful.
have a 2004 c5. Been getting codes on and off for a bit, been trying to track it down.
First thing I ended up seeing as a slow pedal on the graph compared to the throttle position sensor. Bought the kit that gives you a different harness and lets you run a different pedal sensor.
dropped a couple of the codes, 2131 and 2126
still was getting the 2120 and 21 putting me in limp mode randomly.
Replaced the throttle position sensor. Didn't seem to help. When it runs, it seems to skip at certain rpm after I get on it.
I pulled the throttle body off tonight. Doesn't seem to have damage to the butterfly that I can see. It moves ok, when I release it though it goes down and bounces off the bottom. I haven't noticed that on other cars I've worked on - but haven't had to mess with a GM drive by wire throttle body
Any direction to look at this point might be helpful.
Last edited by SILVERCorvetteC5; Jun 14, 2023 at 08:36 AM.
Thread Starter
Cruising
Joined: Apr 2023
Posts: 11
Likes: 0
So debating if it's possibly the tac
Since I wanted to do brakes on this (the ones they had where so dusty and squeaked) I figured I'd take a look. The pocket was full of debris and leafs and such. Wires all look good.
Do these not open - do they require a heat gun to break the seal?
Anyone rebuild them - I know on Duramax the ficm has become an issue lately, and company's like SIA have been able to rebuild 70-80% of the ones that go bad.
Anyways to test it. Hard since its a random issue lately.
Since I wanted to do brakes on this (the ones they had where so dusty and squeaked) I figured I'd take a look. The pocket was full of debris and leafs and such. Wires all look good.
Do these not open - do they require a heat gun to break the seal?
Anyone rebuild them - I know on Duramax the ficm has become an issue lately, and company's like SIA have been able to rebuild 70-80% of the ones that go bad.
Anyways to test it. Hard since its a random issue lately.
Thread Starter
Cruising
Joined: Apr 2023
Posts: 11
Likes: 0
So debating if it's possibly the tac
Since I wanted to do brakes on this (the ones they had where so dusty and squeaked) I figured I'd take a look. The pocket was full of debris and leafs and such. Wires all look good.
Do these not open - do they require a heat gun to break the seal?
Anyone rebuild them - I know on Duramax the ficm has become an issue lately, and company's like SIA have been able to rebuild 70-80% of the ones that go bad.
Anyways to test it. Hard since its a random issue lately.
Since I wanted to do brakes on this (the ones they had where so dusty and squeaked) I figured I'd take a look. The pocket was full of debris and leafs and such. Wires all look good.
Do these not open - do they require a heat gun to break the seal?
Anyone rebuild them - I know on Duramax the ficm has become an issue lately, and company's like SIA have been able to rebuild 70-80% of the ones that go bad.
Anyways to test it. Hard since its a random issue lately.
p2120 p2021 p2126 p2131
Still getting these codes.
So far I've replaced the pedal sensor
The tps sensor
the tac
what else could be causing these codes?
I'm at a lose. It's random but does it every trip, pops limp mode. I pull of reset it and it's fine, or it may do it again.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Find the TAC FUSE. Read the fuse test points on top of the fuse to chassis ground (ignition ON) You should see FULL battery voltage on both test points. Pull the fuse and examine it to make sure its not corroded/discolored/lose. Look at all the Module harness pins/connectors. Inspect for corrosion/damaged wires/ etc.
NO, The TAC Module is a sealed Module and can not be opened without busting the box.
YES, The TB Blade just FLOPS back into position when it is not powered. However, When the Ignition is ON, It should immediately ERECT to the last known good idle position. It should be firm in position and open and close SMOOTHLY with peddle position. You will be able to hear the stepper motor move it through its quadrants as it moves.
NO, The TAC Module is a sealed Module and can not be opened without busting the box.
YES, The TB Blade just FLOPS back into position when it is not powered. However, When the Ignition is ON, It should immediately ERECT to the last known good idle position. It should be firm in position and open and close SMOOTHLY with peddle position. You will be able to hear the stepper motor move it through its quadrants as it moves.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
You can also pull the TAC Fuse and place a DC AMP meter in the fuse slot to make sure you are getting proper current to the circuit. List the voltages you get on the fuse to ground and what current the TAC Module draws.
Thread Starter
Cruising
Joined: Apr 2023
Posts: 11
Likes: 0
Find the TAC FUSE. Read the fuse test points on top of the fuse to chassis ground (ignition ON) You should see FULL battery voltage on both test points. Pull the fuse and examine it to make sure its not corroded/discolored/lose. Look at all the Module harness pins/connectors. Inspect for corrosion/damaged wires/ etc.
NO, The TAC Module is a sealed Module and can not be opened without busting the box.
YES, The TB Blade just FLOPS back into position when it is not powered. However, When the Ignition is ON, It should immediately ERECT to the last known good idle position. It should be firm in position and open and close SMOOTHLY with peddle position. You will be able to hear the stepper motor move it through its quadrants as it moves.
NO, The TAC Module is a sealed Module and can not be opened without busting the box.
YES, The TB Blade just FLOPS back into position when it is not powered. However, When the Ignition is ON, It should immediately ERECT to the last known good idle position. It should be firm in position and open and close SMOOTHLY with peddle position. You will be able to hear the stepper motor move it through its quadrants as it moves.
I'll have to run to the hardware store in a bit for some new fuses as I was not getting any dc amps acrossed the multimeter. I'll test again once I replace the multimeter fuses to make sure it's not reading any
Thread Starter
Cruising
Joined: Apr 2023
Posts: 11
Likes: 0
Havent been able to get current yet.
But I removed the accelerator pedal sensor kit I put on, had a crossover harness and different sensor. I put the old one on.
Drove it today to breakfast eventually on the way home I got a p2126
Would this wire e? I believe it says, be from the pedal to the tac. Would I be able to disconnect booths sides (tac and pedal) and check for continuity (sp)? If it's just one wire bad might explain the randomness.
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