Screwy speedo after disonnecting battery

[sagebel]

Why did you disconnect the batteries?

 

[Tbar]

either you did not connect the batteries back up well and youve got a loose ground or you have a bad vehicle speed sensor. Either of them are a cheap fix.

......X2


Tbar

 

[BIG JOE]

......X2


Tbar

X3..... and as mentioned earlier.. the condition of the cables themselves, not just the clamps/connectors.. but the cables, for corrosion.

The reason I say this is... I chased 12v electrical Gremlins (CC, VSS, ABS, Brite/Dim lights) on my 91 for a month. Finaly.. I changed out the Batt cables and ALL issues went away.

 

[Seabass]

Why did you disconnect the batteries?

The "new yellow tops" I bought the truck with both are junk. Spoke with the interstate rep today, new ones should come in today. On a side note I did ball joints on my buddies f250 last night and all went pretty smooth.

 

[Seabass]

New fun stuff! P0478 code appeared when I went to lunch today. Batteries wont be in till tommorow.

What do you think. Possible relation to my other problem? It was the only code stored. Cleared the memory hasn't come back yet. I'm gonna try and clean the tube that feeds the sensor when I have two seconds to myself.
I'm starting to get this tingling feeling of buyer's remorse in the back of my head. Only put 100 miles on the truck so far.

 

[Seabass]

New batteries are in no change in speedo... Cleaned up ground strap on fender. Clamps are clean... cables look ok I haven't ohmed them out but the don't look bad. I'll call in some favors tommorow with a friend of a friend who is a writer at a ford dealer to see if he has seen anything like this... Side note. Does the computer look at the speedo to adjust shift points?

 

[sagebel]

Sort of. The PCM needs a good input from the VSS to determine when to shift. A bad VSS can give you odd shifting, no CC, and a few other symtoms. I don't remember if my bad VSS caused the speedo to act up. Is it possible that you got a bad VSS when you replaced it?

 

[BIG JOE]

I don't remember when F-??? trucks went Digital but.. if it's Analog It could be the Speedo or the cable has gone bad.. or both ??




My 91 Speedo went south at about 90+K IRC. Bouncing, sticking, then did'nt work at all.

 

[Seabass]

Edit my earlier statement cruise does work.

 

[hawkdriver]

I still have a similar issue with my '01. My batteries went south about 5 months ago and ever since then my speedo doesn't work at all. Cruise works just fine so I'm thinking the VSS is fine. All the lights in the dash work as advertised. I have just been driving without the speedo and using the tach and my GPS occasionally. I'm still looking for ideas on what to check next. My luck is going to run out eventually with my friendly speed enforcement officials....