Scanmaster reading speed wrong

[4cd-Air]

My scanmaster says I'm doing 85 when I'm doing 45? What the hell is up? VSS bad? Wrong connection? My stock speedo is right, so I don't know.

 

[Steve Wood]

If the speedometer is right, then I guess you don't have 13 inch wheels on it...

There is no vss code present?

 

[Turbo__Tim]

Call Mike first, but there is something wrong there. I'd send it back. If you can do a computer swap first so much the better..

 

[4cd-Air]

Originally posted by Steve Wood
There is no vss code present?

No codes at all. I had codes last week, oxy sensor and ATS, both I fixed. No codes for this though. Also my tranny has been acting weird, but I have a thread about that in trans talk. Could that have anything to do with it? The stock speedo is correct, that is what's throwing me off.

 

[Steve Wood]

It might have something to do with the tranny problem...depending on what it is doing...if it is sending the ecm the wrong speeds, it might cause a problem...I am not sure how much the tranny depends on the vss other than lock up and such.

 

[bruce]

A dry speedo cable can be chattering and false trggiering the sensor in the back of the speedo.

Also, any grease stains/streaks on the shutter on the sensor can do it.

Plus your regular electrical gotchas

 

[87gnblackdemon]

Mine has read the wrong speed since I've had it, speedo reads right even after going to the 185mph speedo. I don't watch mph on the scanmaster so I didn't care that it was wrong, all other numbers seem right. It this something that really needs to be fixed? Could all other numbers be wrong too?

 

[4cd-Air]

Originally posted by 87gnblackdemon
Mine has read the wrong speed since I've had it, speedo reads right even after going to the 185mph speedo. I don't watch mph on the scanmaster so I didn't care that it was wrong, all other numbers seem right. It this something that really needs to be fixed? Could all other numbers be wrong too?

See, all my other numbers seem right too. I don't read my speed from the SM, but I'd like to know it was right anyway.

 

[Black Car]

You have a modified speedometer ?
Do you have a reducer on the speedometer cable?
If so, then this could be the problem.

Gary

 

[Mike Licht]

The Scanmaster only displays what the computer sees from the VSS. Do you have a digital dash, or GNX style dash, or 145 speedo conversion?
Mike

 

[blackbuick87]

I have the 145 speedo conversion and my scanmaster reads way low. I expected this. I would think something else would cause his to read high