01 Grand Marquis Speedo

I have a 2001 Merc. Grand Marquis with a digital dash. The problem I am having is that the speedo displays 0 intermittantly. Any idea what may be causing this? The cruise control will still work if I set it when the speed is showing.

The speedometer reflects the vehicle speed from the signal it receives from the Vehicle Speed Sensor. If there were a problem with the VSS the Check Engine light would be on because the computer also receives the signal from the VSS.

So, if the Check Engine light isn’t on, the problem’s got to be with the speedometer head/instrument cluster.


While I’m not familiar with the digital cluster on these cars I might have to respectfully disagree about the VSS if my Lincoln in any indication.

A few months ago the speedometer hiccupped a few times and reverted right back to normal. Some miles later the speedometer quit along with the cruise control. The only other symptom was an illuminated OD light. The final 70 miles home was made by gauging the tachometer.

There was never a CEL and a scan showed no codes at all. Testing the VSS with a VOM showed it was stone dead and after replacing it everything has been fine since.

Where is that sensor located Ok?

The VSS on my Lincoln is on the tailshaft and AutoZone shows the VSS on a 2001 Grand Marquis is also located on the tailshaft. Maybe the digital dash is a different beast and if so, it’s a stupid move by turning a 5 minute, cheap repair into a major and expensive headache.

2001 Mercery Grand Marquis LS. Has 122,000+ miles on it. The speedometer will intermitently register a Zero in place of actual speed. When this happens: Odometer does not advance, Miles remaining in gas does not reduce, Miles per gallon reads 99.9, Cruise control still functions and now the Trunk Ajar light and audio goes off every now and then. Check engine light does not illuminate. Used to coincide with bumps in road, but not now. I can smack either the dash above the digital dash board or the steering column below it when this happens and the MPH will jump but return back to Zero. Ford dealership said it was either the speed sensor or the sensor cluster but could not duplicate for verification. Any help? I know I can get a refurbished digital dash from advanced auto parts but want to make sure this is the likely problem instead of a sympton of a loose wire/connection. Also, Parts store said they only had a refurbished dash rated to 120 MPH. I don’t know which I have but when I bought it used, it had a factory installed high performance exhause on it.

2001 Mercery Grand Marquis LS is doing the same thing Speedometer “0” and the Trunk Ajar light. Have not found the solution yet.
I thought it was Gremlins, battery terminals maybe needed cleaning but that did not help as a matter of fact when I got in the car after cleaning the terminals the speedometer stayed at ZERO.

The problems you’re all having could be because of a defective Transmission Range Sensor. Or as us in the business call it the PRNDL (prindle) switch.

When this switch malfunctions it can cause all sorts of goofy problems. The dash lights will turn off and on. The entertainment system will turn off and on. and the interior lights will turn off and on.

I’ve never seen a PRNDL switch fail on a vehicle with a digital speedometer. So I can’t say if it can effect it. But if you have electronic components on the dash turning off and on, or the lighting is turning off and on, look at the PRNDL switch.


If hitting the dash makes it temp work, than take it out and reseat all the connectors or get a bigger hammer.