SnowyATX

Yes, I've done some searching but haven't found anything on this particular scenario.

Car has about 30K miles.

Twice in one week, the speedo dipped to zero for an instant (say around 30mph) and then a "service traction control" message showed up on the DIC. No change in drivability.

I do have the telescopic steering column but its always in the "pushed in" position for what its worth.

Would seem like I have a wheel/speed sensor going out or something.

Anyone seen these specific symptoms?

And now, I haven't had time to go check the codes yet.

SnowyATX

TTT

Anyone else? This has happened several more times since my original post.

torquetube

A dying speedo sender / bad connection sounds like a good working theory, but you're really at sea until you retrieve the codes.

GM should have made the codes retrievable through the DIC, but they didn't. Consequently, every C6 owner really should have at least a basic code reader in his toolbox. They're cheap.

I think going to the auto parts store and buying a reader is the next step.

SnowyATX

P0503 - Vehicle speed sensor (VSS) intermittent.

Guess I'll start out by checking the connector and harness down at the sensor.

SnowyATX

Well.....stike one. That sensor is not accessible without yanking some stuff like maybe the shock and half-shaft. Yuck ....I did enough of that on my C5 (like multiple times and I'm still sick of it).

VET4LES

Where is it?

SnowyATX

Sensor/harness on top of the diff (lower right in the pic).

VET4LES

Thanks.

djbrun

+1 on the VSS sensor, or vss sensor circuit.

KarlK

Mine's done it 3 times. Last one as recently as a month ago.

SnowyATX

Mine is still doing it several times per month. If cruise is on the cruise control shuts down (of course).

SnowyATX

Anyone else having this issue?

SnowyATX

Ttt

Gearhead Jim

Whether or not you wanted to, you paid for a warranty when you bought the car. There actuallly are some dealers that do good work, I'd ask around and give them a try.

Good luck!

SnowyATX

Well, still having the random speedo drop outs. Today I was pulling a code for the drop out from yesterday and got the same P0503. What was interesting was while I was still sitting in the car I turned it off and restarted it...and didn't do anything else....and then I got the service AH, TC, etc on the DIC. I've never seen that before. Checked the codes and now it has a P0856. Reallly weird that the new error on the DIC and code showed while I was just sitting in the car.

Reset the code, restarted it and now no error even after driving.

I don't use the telescoping feature but I do tilt it up and down everytime I get in and out of the car. I've tried resetting the connector at the VSS. Guess that sensor could be intermittent and or the yaw sensor from what I've read. yuck....

Chonger

This has happened to me once or twice in a span of 3 years. It just went away the next time I started the car.

Kinda weird.......

SnowyATX

All,

I did some debugging on the code per the manual, i.e. some resistance measurements at the ECM, and luckily it didn't definitively point to something other than the sensor so I figured I'd throw the $30 at a new sensor and see what happens.

I did that on the 7th and haven't had any issues. My speedo bouncing (insert BAD mental image here) is quite rare but my cruise would misbehave ALL the time where it would disengage all by itself. I've been using the heck out of the cruise and no issues yet. Not going to call it a success yet but it looks like I "may" have solved the problem. Oh, and while I was down there I tie wrapped the cabling on the driver's side of the tranny so it couldn't move around as much. There was enough slack for it to move around quite a bit. Wouldn't that be ironic if that was the issue.

CGZO6

Glad you fixed it, must have been driving you bonkers for the last 15 months.

Gary-kq6rt

I've had my 2008 base coupe for about 2 months now and my car has done this twice. I'll wind it to the top of third and as soon as I hit fourth the speedometer drops to zero until a few seconds after I let up. The Hud also shows zero.

Can anyone tell me how fast 5500 rpms in fourth gear is? That's the fastest I had a chance to get it to so far.

vette6500

Check speed at 2750 rpm in 4th, then double it.