Edit: Update for solution.


There was an update sent out 8-MAY-2015 for this. DTC P0503 (H0503)

#PI1439A: Malfunction Indicator Lamp (MIL) Illuminated, DTC P0503 Only Set with No Other Symptoms.

Models: 2015 Chevrolet Corvette
Equipped with Manual Transmission (MEK or MEL)
Built Prior to VIN BReakpoint F5606174

Recommendation/Instructions:
Important: Do NOT replace the vehicle speed sensor for the issue.

If following the diagnostic instructions for this code above in Service Information (SI) does not lead to a root cause, update the Engine Control Module (ECM) software.

An revised software calibration has been released to address this condition.

Update the Engine Control Module (ECM) using the Service Programming System (SPS) with the latest calibrations available on TIS2WEB. Refer to the K20 Engine Congrol Module: Programming and Setup in SI.

Warranty Information
For vehicles repaired under the Powertrain coverage, use the following labor operation. Reference the Applicable Warranties section of Investigate Vehicle History (IVH) for coverage information.
Labor Operation: 2810075 ----- Description: Engine Control Module Reprogramming with SPS ----- Labor time: Use Published Labor Operation Time.


Original Post Below


Code has now popped on 4 times. First two times were from regular driving/cruising; just going down the road and it popping on. Last two times were these weekend, notably doing burnouts. I'll be dropping it off at the dealership for the third time to get looked at which I'm sure they'll say "Oh, nothings wrong." clear it, and send me on my way for it to come on again. On one side, its a pretty benign code and doesn't do anything to the drivability of the vehicle. On the other hand, what good is a corvette if it can't even do a proper burnout without going awry?

Anyway, do I have any negotiating power w/ GM? Does it qualify as a lemons? I'm not gonna lemon the car, but see if they want to give compensation for this reoccurring issue.

 

What kind of a message are you getting? As far as I know the car doesn't exhibit any codes only messages or lights such as a CEL. There are hundreds of codes that then generate those few messages or turn on a light. The C5 models were the only make ever on the market where all of the codes could be displayed on the DIC by using the DIC control buttons.

Bill

 

Kinda like Bill was getting at. Which code(s) are you getting?
There at least 3 or 4 codes related to the speed sensor. The code will tell us a great deal.

By nature though simple the VSS circuit is one of those things that can easily be troubleshot and not found faulty. This is because the sensor is a magnetic inductive pickup that may work or look good while the car is sitting still or moving slowly.

Point is if you have any influence with the Service Writer insist they change the VSS pick up. It’s relatively cheap and unless you have a wiring problem the VSS is the culprit. Otherwise they may keep checking yours (which is probably marginal) and not finding anything wrong. It’s a simple circuit. If it sets a code most likely the sensor is going bad.

 

I honestly forgot the code number (05 something). Car now has 3200 miles and has tripped the code 4 times causing the CEL to pop on. After a couple hours, it goes off. Its done this once at 400 miles, once at 1600 miles, and twice within the last 200. Every time (twice) I've taken it to the dealership, they look at the code in the history, clear it, and say "we can't replicate" and send me on my way. Obviously its coming on and they can see it, but the same old "can't replicate" doesn't mean there isn't a problem as they can obviously observe the fault. I've scheduled for my car to go in again, and this time the regional service guy is gonna take a look at it. I don't want to lemon the car but I am tired of it going back into the shop. Hopefully they get it figured out this time, if not, a new set of SC2's would make me whole

 

Here is the problem the dealership is having. The code clears and leaves a mark in history and maybe in some fault records. However, while they have the car it is performing normally and they don't see any data that is out of line with normal operation. What are they supposed to fix? The system is working as it should. First rule all of us learns is to not fix something that isn't broken. For this kind of problem you don't make an appointment. You make prior arrangements with the Service Adviser telling him you will immediately bring the car in when the failure reappears. When that happens you immediately drive to the shop, leave the engine running and run in say I am here and it is failing. It may take a few moments till they can clear a mechanic to bring a Tech 2 out to the car but that is the best way of seeing if they can ID the fault.

Sure you might be able to bring up some sort of Lemon Law issue but what good does that do you? Lemon Law cars usually turn out to be very good cars for the second owner and they may even get the car at a great price.

Bill

 

OK. You may not believe this, but I'll try anyway. I have had the same thing happen repeatedly. I have a theory as to why. So while I'm at the bash a couple of weeks ago I asked the " experts". They said that they don't know. They don't know what the car is " thinking " for when ck eng lights come on. They just know what parts to replace given which system it relates to. They said all of the software comes from outside suppliers. I openly laughed at them. Even if they don't know you don't say that in front of large groups of people. Anyhow, my theory is that when doing a burn out in certain modes the car senses that the rear tires are turning and the fronts aren't so it thinks that the VSS is malfunctioning and throws the ck eng light. BTW if at the drag strip and you get the light it should go into reduced power mode and not leave for **** or that's what mine did. The ck eng light will go out after driving so many miles or so many ignition cycles. I put my car in the weather mode, thinking it wouldn't go crazy because it thinks it is in snow or ice and that would be expected in those condition. Every single time that I have done that, put in weather mode for burnout, it hasn't happened again. I'll bet that it will work for your car to. Then after your burnout go into whichever mode that you want to make the pass in. I use track/race with all the nannies off and get full power without it holding back.

 

So bumping this back to the top. Car was finished being worked on today. GM had released a bulletin on this 2-3 weeks back as it was apparently a software issue. They reprogrammed the car and said it should be taken care of. If you have your VSS code pop on and you have one of the early vehicles, keep this in mind.

Cheers,

 

Well I didnt consider that one. If the PCM is to sensitive it could be miscounting/undercounting. If thats the case a recalibration would likley fix the issue.

 

Thanks for the follow up. I got one P0503 VSS CEL Code at like 700 miles that hasn't re-occurred since, but it's good to know it is SW related. I checked the VSS weather-pack connector while I was putting on my CAGS defeat and nothing obvious wrong there. Again, only one CEL event that OnStar read out the P0503 "speed system malfunction" code to me.

Any idea what the Service Bulletin # is? Mine's a relatively early car, VIN #1515...what's yours?

 

P0503, if u don't get that code every couple weeks u must not be spinning the tires.....as far as I can tell, a very large number of c7z's are doing this.

There also seems to be an issue with drag strip launches and power reduction that I am certain is in the factory tune.

 

I'll ask for more info this evening when I go pick up. #1881. First time they did the same thing; reset the connector; couldn't replicate problem and sent me on my way.

Second service visit: Couldn't replicate and sent me on my way.

Third time's a charm I hope.

First couple of times it had nothing to do with spinning the tires. I think the code was simply too sensitive. Code never reduced power or had any side effects other than popping a CEL.

 

I'm one of the ones that has had that problem at the strip. If you do your burnout in weather mode it won't throw the light. Its only a little inconvenience.

 

 

Picked the car up this morning. Got a copy of the info that went out on this. Looks like this issue applies to VIN's 6174 and earlier. If you get this error, here's relevant info for it:

#PI1439A: Malfunction Indicator Lamp (MIL) Illuminated, DTC P0503 Only Set with No Other Symptoms.

Models: 2015 Chevrolet Corvette
Equipped with Manual Transmission (MEK or MEL)
Built Prior to VIN BReakpoint F5606174

Recommendation/Instructions:
Important: Do NOT replace the vehicle speed sensor for the issue.

If following the diagnostic instructions for this code above in Service Information (SI) does not lead to a root cause, update the Engine Control Module (ECM) software.

An revised software calibration has been released to address this condition.

Update the Engine Control Module (ECM) using the Service Programming System (SPS) with the latest calibrations available on TIS2WEB. Refer to the K20 Engine Congrol Module: Programming and Setup in SI.

Warranty Information
For vehicles repaired under the Powertrain coverage, use the following labor operation. Reference the Applicable Warranties section of Investigate Vehicle History (IVH) for coverage information.
Labor Operation: 2810075 ----- Description: Engine Control Module Reprogramming with SPS ----- Labor time: Use Published Labor Operation Time.

 

Thanks for the information!

 

Thank you very much for the info.

 

Great work. Time to update my computer software then. I got this code several times now.