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Speedo WAKEUP!

blu_fuz

blu_fuz

New Member Classroom vulture
Joined
Sep 25, 2002
Messages
16,028
Location
Waupun, WI
This happens just about everymorning now. I can drive 3-5 miles without the speedo working at all, then it starts to come alive!

As it's waking up you can see the needle slowly moves around.

But the strangest thing, only for a minute or two, as I am shifing and accelerating it does some crazy stuff.


You can see when I am on the gas the RPMs go up as normal, the SPEED drops :eek:. As soon as I am off the gas and into a shift, the speed jumps back up! :laugh: It flip flops like that only a few minutes.

After driving for about 7 miles the speedo is back to normal :shrug:.

 
that is....interesting.

im going to say that you have a wire that has rubbed through somewhere and it is grounding itself out. if its doing it when youre shifting that is when the motor it moving so its making the wire touch
 
It doesn't only move with throttle position/motor movement, I can make the speedo jump like that by pushing any 2 of my window switches at the same time :laugh:. When the brake lights are on, the speedo needle will also drop to 0 and I can make the needle swing with the blinker rythm too.

I have some kind of voltage/power issue in the system, just gave up on trying to fix it.


 
just keep one of these videos on your phone so you can show it to the officer when you get pulled over
 
I had a bouncing speedo issue on my 2000. My hood ground was not attached, so I looped that back to the inner fender and cleaned the others, The one in the block under the WP can get a little oxidized I saw.

It clear up my troubles, I then shortly after put an alternator in.

I think pre 98 speedos are cable driven, no? Alot of times its the wire rappings that are broken brushing against them selves making the speedo operate.

Im not sure when you last had the dash apart (Chrome rings), but too much pressure on the needle up against the gauge face can leave the needle in place and the pin rotating. If that had happen once it can then cause the need to be in deficit causing off readings. I only mention because if your not get accurate readings as well, it might be a combo of things.

TE
 
Not cable, and I have had 3 different clusters installed with the same issues.

Also went around to all the grounds in the engine bay, sanded the body down to metal, and sanded the connectors clean, re-connected everything and no change.

The speedo will actually read the correct speed and work properly after about 5-7 miles and continues to work throughout the day.
 
Did you ever clean up the grounds in the driver and passenger kick panels? Pretty much every interior wire runs to them so cleaning the engine grounds won't help.
 
i had the same issue after installing my msds headers. the headers burned my speedo wire to that connects to the tranny. dont just check the connector check the wire... hope that helps.. and on demand5 is saying the ground for the vss connector is on the battery support?that might be the ground your looking for..
 
I know a defectice alternator that is bleeding ac into the system can cause all kinds of havoc in the system. If you can't find an iasue with the wiring then that may need to be your next step.
 
Joe is it sensor driven or cable driven? If sensor did you ever look at the wire going into the speed senor? They had a bad design on the wiring to the VSS and it made it vulnerable to vibration. Every single VSS I've seen has shown signs of wear right at the corner on the VSS plastic housing.

When I rebuilt my trans back in 05 I replaced my speed sensor for the same reason. When I pulled my engine out in 09 the brand new speed sensor I had installed was starting to show signs of wear too. So yea, just sayin...
 
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Electronic speedo and I have a brand new OEM VSS installed. Speedo is acting exactly the same with the new VSS as it did with the old VSS.
 
Joe Little off topic but i was blown away once i got my package from you this weekend
That is going over and beyond the call of duty for an old guy you have never met...amazing
thanks doug
 
terryford8 said:
Joe Little off topic but i was blown away once i got my package from you this weekend
That is going over and beyond the call of duty for an old guy you have never met...amazing
thanks doug
Click to expand...

No problem Doug! You can leave me feedback in the feedback forum so it's easy to find.


Those needles came off of the spare cluster I swapped into my car to test this system.
 
The battery I have is from '07, soooooo could just be a voltage drop issue with the battery. :ponder:
 
You ever going to check the grounds? This is the second time I told you the grounds run to the kick panel before and you never responded so I assumed you didn't check and/or don't believe me.

Clean those up, if it perists check the square wave (ppm) with an oscilliscope to the dash cluster speedo wires. You'll have to pin it out yourself but its easy just look at the speedo and follow the traces. I have a 98 svt dash and it all works correctly I had to trace them it can be done in 2 minutes.

The VSS is a hall effect sensor. Look it up if you don't know how it works. Check you have 5 volts (consistently) to the vss. Check the PPM with an oscilliscope. If the voltage is steady and and the square wave is there and not dropping out and you have tried multiple VSS's and clusters than the only other thing could be.....the ground from the speedo to the one in the kick panel...............................................
 
2000ZxT hit the nail on the head... time to start checking grounds. But would definitely check the battery, alternator, 5v supply to VSS first.
 
Like we all have an o'scope at home.....think not ;-) jrichardson mentioned alternator with issues (specifically bleeding AC to ground). I have seen this before. So, check grounding first and then alternator should keep you busy and hopefully provide a "hit".
 
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