VS speedo giving an incorrect reading...

[gtsmoker]

Hi guys,

Just bought a vs II acclaim, when i am getting up to 60km/h the speed alert kicks in when the analog dial reads 55... Guessing my actual speed being about 61km/h

Which one do i believe? Is this normal or can i get it fixed somewhere. I dont want to get a ticket!

[nathanVY]

Whats your wheel size and tyre profile?

[gtsmoker]

just the standard 15 inch

[nathanVY]

check it's the correct profile tyre, the wrong ones will throw the speedo out. Should be 205/65/R15, take a look on the side of your tyres (check the front and rears on both sides)

[gtsmoker]

yeah thats the profile mate. I cant work it out, would it more likely be the speed alert or the analog dial? im thinking the speed alert, but really i have no idea..

[nathanVY]

could be the VSS (vehicle speed sensor) inside the transmission, run an error codes check Checking error codes VR/VS (Revised)

[gtsmoker]

did the code check and it gave me 1 flash followed by 2 then a break and then repeated. So i guess that is 12 meaning no issues....

appreciating your help mate

[nathanVY]

cool, ok try starting it in diagnostic mode.

put the key in the ignition
hold mode and set on your trip computer
start the car
you should now have various new and exciting readings on your digital dash
keep pressing mode and scrolling through until you see speedo, should say 0km/h (unless you're moving when you do this lol)

go for a drive and compare the reading of the digital speedo to the analogue one.

all assuming you have a l3 cluster haha

[gtsmoker]

I only have a standard acclaim, i have a set button on the speed alert but i dont see a mode button anywhere.....is this for a stato dash??

[Brett_jjj]

The speed alert on the lower end commodores also has a digital speedo mode,just hold all the buttons in on the speed alert module whilst you start the car.I cant remember the exact process,but I think that after holding them for about 10 seconds, you then just press the set button, and it should change to 0km/h on the LCD reading.Some speed alert modules will set to a permanent speedo mode,and theres also some other speed alert modules that will only set to speedo mode temporarily with a flashing orange light,and these type will revert back to the speed alert function once the ignition key is turned off.Also if holding the 3 buttons in doesnt work,just try holding in the two outer (arrow) buttons in whilst starting the car.

[gtsmoker]

Brett, can you read my original text and see if you have any ideas?? I cant work it out.

[Brett_jjj]

Ive just been checking out the wiring diagram in the workshop manual to see where the speedo etc get their speed signal, and the speedo gets its signal from either the speed sensor on a manual transmission,or from the ECU on an auto trans,via a Violet/white wire,and so does the trip computer, if one is fitted,but I cant for the life of me see where the speed alert module gets its speed signal from,cars that dont have the trip computer fitted,usually have the speed alert fitted instead,so its really got me stuffed.Theres just no wire from the speed alert module to the speed sensor or ECU.Id try to set the speed alert to the digital speedo mode like I mentioned in the above post, and see how much difference there is between the speedo reading and the digital speed reading on the speed alert..if its the same,then the speed alert module might be stuffed.It just pulls out of the dash and unplugs,so they are easy to change over if thats the case.

[hako]

If you read the owners handbook (the one in the glovebox), it says something about a fudge factor built into the speed alert - means that if you dial 100kph into the speed alert, it will only sound when you hit 105kph or thereabouts. I'd guess that it's designed that way because normal car speedo's traditionally over-read....this makes you think you are going faster than you actually are.

[Chappo_1]

Do you have a GPS you can use?
According to my GPS, my speedo reads 5km under. When my speedo says 60km/hr, the GPS says 55km/hr.
Who's to say which is correct though :/

[adrian123443]

I have a Vs berlina when I'm travelling at 100 k's my gps reads 92, I found the easiest solution is just to go 108