RoadkingC6

Thought i would ask here not really sure if this is where the problem may be, thought i would check here, in my 2005 Vette the speedometer is not working, the HUD unit and the speedometer cluster is not registering the speed, the other functions such as the tach, and gauges all work fine, at first the speedometer would from time to time stop working, then start working while driving or on re-starting the car at a later time, it would work fine for long periods of time and then just stop working, presently it's not working at all, i have a Pioneer 940BT radio in my car it was installed over a year or so now, i was thinking maybe the VSS wire could maybe have a bad splice i believe this wire is used for the GPS speed function on the car, not sure if my thinking is correct and if this wire would have anything to do with my problem, does anybody know what the color markings are on this wire, i don't have the installation instructions and the Pioneer cd disc only shows instructions for the radio functions, not sure but if this is not the problem i'm thinking the next area to check would be removing the gauge cluster and taking a look back there, but the radio section would be easier, any help would be appreciated.

markcz

The Pioneer VSS wire is pink.

2007 C6 radio prints are HERE, VSS is in C2 if your car has it (early non-bose may not).

If you don't have VSS in the radio harness, info to find it in dash harness is HERE

My guess... the installer used a splice tap on the dash VSS wire and over time it has cut the original wire at the tap point. If that's it, you can easily fix it by cutting the oem wire on either side of the tap and reconnecting all 3 wires inside a crimp plug.

Happy hunting

RoadkingC6

Thanks for the help MarkCz pulled the radio and as you said the vss wire was pink followed it back and it went into an axcess connector and then into the cars connector, the splice to the radio was good, so i went and pulled the gauge cluster and saw no visible problems, pushed on the connections at the back of the gauge cluster and put the car back together, drove the car and the speedo worked for 6 miles until i turned the car off then when i started it up again the speedometer stopped working, by the way i was wrong, i think it was easier to pull the gauge cluster than the radio, i asked my car mechanic about the speedometer problem, he said sometimes aftermarket radios don't communicate with the cars electronics properly and may cause problems he also suggested taking any am radio and playing inside the car to pick up any interferences in the system he said sometimes you will pick up an audible whine in the am radio if there are any issues, im not really buying into this theory just thought i would get your thoughts on that, the guy i bring my car to is a good mechanic and he didn't say this was the problem he just put it out there as a possibility and then he printed out a schematic from GM a checklist schedule for speedometer problems, i however do not have the scanning equipment required to follow through on the checklist of events, so the hunt continues.

markcz

You can prob rule out the radio as the issue if you snip the pink wire and verify that it still doesn't work. But if you cut the wire and it works fine, it could be the radio.

Does your HU have a vehicle speed display on it? If yes, does it work when the speedo is out?

RoadkingC6

Yes the HUD has a digital speedometer, but when the speedo on the dash stops working, the speedo on the HUD stop working also.

RoadkingC6

Hi MarkCz, I just snipped the pink Vss wire on the radio and the speedometer is still not working, so just to confirm you would say the radio is not causing any of the problem, i am going to splice the wire back into the system and put the console back together, Thanks for the help.

markcz

HU=Head Unit (the radio itself), does your model have a screen that displays the car's speed? If so, does it display properly when the dash goes out?

RoadkingC6

I never noticed a digital speed display on the head unit, so i went through the Pioneer manual and it only shows a estimated time of arrival readout, the HU shows one clock in the upper right corner of the actual time and a small clock below it showing the ETA based on the average speed your traveling, no digital speed readout though, and the ETA function is working. searching the google function i came across a thread from a CF member who had a similiar problem and he changed what is called a VSS Speed sensor located above the rear differential, this transmits a signal pulse to the ECM and gives the speed info to the ECM which sends the info to the speedometer, this could possibly be the issue, im gonna put the car up in the jack today and remove the sensor, from my research i learned there are three speed sensors one for each rear wheel responsible for giving speed info for the ABS braking system, and the one over the differential, unfortunately this is a special order part and will take a couple of days to get, so today i'm gonna take a look to see that the connector is coupled on tight and if so i will order the part and replace it, there is a continuity test they say you can do to check it, i figure if my problem is erratic then i probably can't trust any reading i get and the part is just under $70.00 so it's worth it to just replace it. Hopefully this is the problem.