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Old 11-21-2012, 04:29 PM   #1
ajchance
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Default Change wheels --> error codes?

I apologize if this is a frequently addressed issue...

2001 model with aftermarket Z06 style wheels (18/19 inch). I'm also getting the traction control/ABS etc errors about 90% of the time each time I drive.

Before I get started troubleshooting grounds, EBCM, etc, will the fact that I have 18/19 inch wheels and not 17/18 inch stock wheels make a difference in triggering the errors? I'd hate to go through all the work only to realize that the wheels will always be an issue.

Thanks in advance!
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Old 11-21-2012, 05:30 PM   #2
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My first thought would be what are the rolliing diameters of the tires front to rear? The stock setup uses smaller diameter tires in the front than in the rear, and I would think the traction control algorithm takes this into account. If the diameter bias is outside that algorithm, it thinks something is wrong. My $.02 but more technologically astute need to chime in.
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Old 11-21-2012, 05:34 PM   #3
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Quote:
Originally Posted by PhilsFRC View Post
My first thought would be what are the rolliing diameters of the tires front to rear? The stock setup uses smaller diameter tires in the front than in the rear, and I would think the traction control algorithm takes this into account. If the diameter bias is outside that algorithm, it thinks something is wrong. My $.02 but more technologically astute need to chime in.
^This.
What size tires are you running front and rear?
Ideally you would want the front diameter to be 1" smaller than the rear. Some people have gone as little a .5" and as much as 1.5" difference, but it gets real "iffy" at those margins.
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Old 11-21-2012, 05:40 PM   #4
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You need to tell the PCM you changed the tire size front and rear with editing software. The PCM is looking for 17/18 size tires if it still has the stock parameters.
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Old 11-21-2012, 05:41 PM   #5
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As already stated, overall tire diameter and NOT wheel diameter is the controlling factor. You need to select tire sizes for what ever diameter wheels you have to keep the rear overall diameter larger than the front overall diameter. The 0.5 to 1.5 range started above is workable. Below 0.5 and above 1.5 is asking for problems........
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Old 11-21-2012, 05:43 PM   #6
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you should also post your codes to make sure your on the right trail.
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Old 11-21-2012, 05:43 PM   #7
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Originally Posted by bmfvette View Post
You need to tell the PCM you changed the tire size front and rear with editing software. The PCM is looking for 17/18 size tires if it still has the stock parameters.
Absolute not necessary.....I and tens of thousands of other C5 owners went from 17/18 to 18/19 and had to change nothing.....
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Old 11-21-2012, 05:57 PM   #8
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It's the C1214 code.

Sounds like I should pursue the troubleshooting. I'll look into getting the TPMs next time I get tire work done. If I get into a bind, I have a friend with a TPM programmer and I can get him to help me out.

Thanks for saving me the time!
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Old 11-21-2012, 06:58 PM   #9
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Code C1214 is a repairable code on the 2001 and newer EBCM. Either remove the EBCM and send it off to a repair outfit like ABSFIXER or repair it your self. Here is a link on doing the latter for 2001 and newer EBCM's:

http://forums.corvetteforum.com/c5-t...r-fleabay.html
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Old 11-21-2012, 07:02 PM   #10
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That is an ABS code. I have always had the theory in troubleshooting-"what changed"? In your case wheels and tires. While my in depth knowledge is with BMWs (21 years), having recently returned to the Corvette fold, most things "operate" the same. For ABS/traction/slip control, the computers use a counting ring on the hub, and compare the rotation (velocity/RPM) of all four corners, or front/rear (ABS), to determine an outcome. E.G. for ABS, if one wheel is rotating more slowly than the other three, it is determined that the wheel is "locked up" and braking (hydraulic pressure) is reduced. With traction control/slip control the idea is the same--something's going faster or slower than it should, and brakes are applied or released. When the programmed algorithms are exceeded, the system says "tilt" (code)-something is wrong. If your tire diameters are not "staggered" sufficiently, the computer says "tilt" and throws a code. You haven't stated what your rolling diameters are (above +/- limits), but there are formulas to compute them, or you can look them up on the manufacturer's website for your brand. I would bet you the adult beverage of your choice that the tire diameter "split" is your problem. TPMS have nothing to do with it. OUT.
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Old 11-21-2012, 07:05 PM   #11
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That being said, if the wheel tire combo has been on for a while and this is a NEW fault, then it could be the ABS computer.
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Old 11-21-2012, 09:41 PM   #12
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Quote:
Originally Posted by bmfvette View Post
You need to tell the PCM you changed the tire size front and rear with editing software. The PCM is looking for 17/18 size tires if it still has the stock parameters.
Sorry but that's 100% incorrect. No offense intended.
This is VERY often misunderstood.

Quote:
Originally Posted by 8VETTE7 View Post
Absolute not necessary.....I and tens of thousands of other C5 owners went from 17/18 to 18/19 and had to change nothing.....
Very true.

Its all about the "Diameter" of the "TIRES" you choose. If you up-size the tires correctly then you will have NO issues.

Check out the the information I wrote on my web site about this.

www.ToqueZ06.com
Scroll down to "How to Determine the correct "Tire Size" for new wheels on a C5 and C5 Z06:"

Here is what I did with my Z06 when I upsized from 17/18 wheels to 19/19 wheels.

Front
Stock 17" Z06 Wheel = 265/40/17 = Diameter 25.4"
New 19" Wheel = 275/30/19 = Diameter 25.6"

Rear
Stock 18" Z06 Wheel = 295/35/18 = Diameter 26.1"
New 19" Wheel = 305/30/19 = Diameter 26.3"

So with my proposed new tire setup:
Front --> Increased the Diameter by only 0.2"
Rear --> Increased the Diameter by only 0.2"

I have never had an issue with Active Handling, or Traction Control.

Its ALL about the Diameters of the TIRES, and has nothing to do with the Rim size.


Quote:
Originally Posted by ajchance View Post
I apologize if this is a frequently addressed issue...

2001 model with aftermarket Z06 style wheels (18/19 inch). I'm also getting the traction control/ABS etc errors about 90% of the time each time I drive.

Before I get started troubleshooting grounds, EBCM, etc, will the fact that I have 18/19 inch wheels and not 17/18 inch stock wheels make a difference in triggering the errors? I'd hate to go through all the work only to realize that the wheels will always be an issue.

Thanks in advance!
Please let me know what Tire Sizes your running.
I can quickly let you know if your issue is due to the tire size your running, or another issue possibly.

Toque
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Old 11-21-2012, 09:52 PM   #13
8VETTE7
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Quote:
Originally Posted by ajchance View Post
It's the C1214 code.

Sounds like I should pursue the troubleshooting. I'll look into getting the TPMs next time I get tire work done. If I get into a bind, I have a friend with a TPM programmer and I can get him to help me out.

Thanks for saving me the time!

Quote:
Originally Posted by PhilsFRC View Post
That is an ABS code. I have always had the theory in troubleshooting-"what changed"? In your case wheels and tires. While my in depth knowledge is with BMWs (21 years), having recently returned to the Corvette fold, most things "operate" the same. For ABS/traction/slip control, the computers use a counting ring on the hub, and compare the rotation (velocity/RPM) of all four corners, or front/rear (ABS), to determine an outcome. E.G. for ABS, if one wheel is rotating more slowly than the other three, it is determined that the wheel is "locked up" and braking (hydraulic pressure) is reduced. With traction control/slip control the idea is the same--something's going faster or slower than it should, and brakes are applied or released. When the programmed algorithms are exceeded, the system says "tilt" (code)-something is wrong. If your tire diameters are not "staggered" sufficiently, the computer says "tilt" and throws a code. You haven't stated what your rolling diameters are (above +/- limits), but there are formulas to compute them, or you can look them up on the manufacturer's website for your brand. I would bet you the adult beverage of your choice that the tire diameter "split" is your problem. TPMS have nothing to do with it. OUT.
Quote:
Originally Posted by PhilsFRC View Post
That being said, if the wheel tire combo has been on for a while and this is a NEW fault, then it could be the ABS computer.
In the case of this particular code on the C5, the power relay in the EBCM is not functioning correctly. It could be the result of a bad ground condition or the relay itself has failed or what is more common is that the solder connection of the relay to the board is a "cold solder" From the OP's post the condition sounds like it started when the wheels were changed. I would start with a check of the grounds. Here are a couple of links related to grounds that should help:

http://forums.corvetteforum.com/c5-t...locations.html

http://forums.corvetteforum.com/c5-t...tion-long.html Post #1

Look carefully at the list of items that are grounded at specific ground points as the EBCM is referenced in more than 1 place. It could also just be a coincidence and the relay issue just happened about the same time the wheels were changed.

Reference the link in my previous post if the grounds turn out to NOT be a problem. The relay CAN be replaced or if examination reveals cold solder joints they CAN be repaired on the 2001 - 2004 C5. TONS of reading on this forum about DTC C1214 if you do a search.

Last edited by 8VETTE7; 11-21-2012 at 09:55 PM.
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Old 11-22-2012, 09:22 AM   #14
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Just to clarify, I've had this car for a week and two days. The code has been tripping since I bought it, so I don't know how long the issue has been around. That was actually the reason for starting the post to begin with since I didn't know if the codes started when the wheels were changed.

I appreciate the links to the diagnostic instructions for the EBCM. When time allows after family leaves town, I'll get on it. I have a modest electronic background (building/repairing guitar amplifiers), so I don't have any trepidations about tearing into the module and giving the repair work a try.

A question for the physicists based on the discussion about tire diameters... If the diameter specs between the different tire sizes are so minimal (0.2" as stated above), I would question why the error codes don't trip as the tire wears down from new to bald. There's got to be a change in size near that just with wear.

The tires that came on the car are Firestone Wide Oval RFTs. They appear to have been all added at the same time since they have similar wear.
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Old 11-22-2012, 09:38 AM   #15
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In theory, they would wear evenly or proportionally, and stay within the parameters of the "bias" built into the ABS/Traction Control algorithm. Question remains, and several of us have asked you, WHAT tire sizes are currently on the car? See Toques site to calculate your rolling diameters and go from there. I'd do that before I started tearing into a bunch of electronic stuff. FWIW.

P.S. I'm not a physicist, just a hobbyist/grease monkey for 48+ years who's broken a lot of s$%t along the learning curve.

Last edited by PhilsFRC; 11-22-2012 at 09:43 AM.
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Old 11-22-2012, 10:24 AM   #16
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Quote:
Originally Posted by ajchance View Post
Just to clarify, I've had this car for a week and two days. The code has been tripping since I bought it, so I don't know how long the issue has been around. That was actually the reason for starting the post to begin with since I didn't know if the codes started when the wheels were changed.

I appreciate the links to the diagnostic instructions for the EBCM. When time allows after family leaves town, I'll get on it. I have a modest electronic background (building/repairing guitar amplifiers), so I don't have any trepidations about tearing into the module and giving the repair work a try.


A question for the physicists based on the discussion about tire diameters... If the diameter specs between the different tire sizes are so minimal (0.2" as stated above), I would question why the error codes don't trip as the tire wears down from new to bald. There's got to be a change in size near that just with wear.


The tires that came on the car are Firestone Wide Oval RFTs. They appear to have been all added at the same time since they have similar wear.


I also am not a physicist. But the code you are reporting (C1214) has NOTHING to do with tire sizes. It's about the main power relay for the EBCM failing resulting in the antilock brakes no longer being functional. Because of this both AH and TCS are disabled. Both require antilock brakes to do their thing and since the antilock brakes are inop, these two get disabled.

Further, if your systems were working correctly and if you DO have incorrect tire sizes on the car that would trigger the TCS/AH to come into play, there would NOT be codes set. It would be doing what it is supposed to do when the sensors in the car tell it that the car is "out of control". Namely it applies the brakes , backs out timing and fuel in attempting to get the car back in control. Codes (DTC's or Diagnostic Trouble Codes) are set when sensors fail to report or report inconsistent information. So don't expect to see codes when AH/TCS is doing what it was designed to do.

The issue occurs when it is doing what it was designed to do and in fact the car is NOT out of control. It's incorrect equipment that is "fooling" the system into thinking the car is out of control and the system is needlessly backing out fuel and timing and applying the brakes. That makes driving the car a NO FUN experience.

The system was designed with the idea that the larger rear tires are turning more slowly than the smaller diameter front tires. When the rear tires "are or appear to be" turning faster than the front tires, the system thinks the car is out of control and takes action to correct that issue. However if your cars EBCM system is in a failed state for the antilock brakes (code C1214) then the AH/TCS is disabled so NOTHING will happen.


I agree with the previous poster in that you should tell us what size tires you are running front and rear. I disagree with the previous poster with respect to front and rear tires wearing proportionally. Fact is rear tires on the C5 wear faster than the fronts though no one has yet figured out why.......

Last edited by 8VETTE7; 11-22-2012 at 10:36 AM. Reason: Sp
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Old 11-22-2012, 10:49 AM   #17
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Fact is rear tires on the C5 wear faster than the fronts though no one has yet figured out why.......

You're right!!!! Wonder if it has something to do with the right hand pedal???
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Old 11-22-2012, 11:07 AM   #18
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Quote:
Originally Posted by PhilsFRC View Post
Fact is rear tires on the C5 wear faster than the fronts though no one has yet figured out why.......

You're right!!!! Wonder if it has something to do with the right hand pedal???
I hear that the research is continuing..........
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Old 11-22-2012, 11:22 AM   #19
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Quote:
Originally Posted by ajchance View Post
A question for the physicists based on the discussion about tire diameters... If the diameter specs between the different tire sizes are so minimal (0.2" as stated above), I would question why the error codes don't trip as the tire wears down from new to bald. There's got to be a change in size near that just with wear.
You never read my full explanation on my web site did you.... Please re-read post #12 and go to my web site and read it all.

Its not 0.2". You completely misread what I was trying to explain to you.

Truth !


Click the image to open in full size.


Your rear tire must be 0.5" larger in diameter than your front tire. If your rear tire is not larger then you will have issues with your traction control, and active handling.

Good luck with your issue.
Toque
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Old 11-22-2012, 12:04 PM   #20
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Sorry, had to wait for everyone to get up before I could check the tire specs.

Front: 245/40R18 (25.7")
Rear: 285/35R19 (26.9")

Toque, sorry I missed your link when I read your post earlier. That's a great tire reference! Looks like my specs should be fine.
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