Speedometer not working

Hi all,
Working on a 94 Town Car for a friend of mine. His speedometer doesn't work. Just from a casual glance, I presume it's electronic and not mechanical (cable driven) Does anyone know a simple way to test these or common problems? A simple search didn't answer any of these questions. Thanks. Doug

Hi Doug,
Common problem with the electronic speedo's is the connections to the cluster assembly.

Some guys report cleaning the connector pins with a pencil eraser fixes the problems, and others have to replace the cluster assembly.

If you plan on working on this car for any length of time, also tyry the guys over at LincolnsOnline (http://www.lincolnsonline.com/cgi-bin/ultimatebb.cgi?ubb=forum&f=3).

Thanks for your reply. Does it make any difference that the speed control is also not working? I was thinking it was probably in the transmission. Any ideas?

Thanks for your reply. Does it make any difference that the speed control is also not working? I was thinking it was probably in the transmission. Any ideas?


Well, now that you mention it...
There is an Output Shaft Speed Sensor (OSS) and a Vehicle Speed Sensor (VSS) on the transmission, they may have come disconnected or have corroded contacts.

However...
The cluster should light up even if these sensors are disconnected.


Here's the reference data from my 1996 manual:
«1996 Town Car/Crown Victoria/Grand Marquis Table of Contents»
«Group 13: INSTRUMENTATION AND WARNING SYSTEMS»
«Section 13-01A: Instrument Cluster, Electronic -- Town Car»
«DESCRIPTION AND OPERATION»

Speedometer

Note:
The symbol KM/H signifies a metric speed display and the symbol MPH signifies an English unit speed display. Units are selected by the E/M button.

The speedometer display:
* Provides speed information based on a speed/distance pulse signal (specific number of pulses per mile) from the transmission-mounted vehicle speed sensor (VSS) (9E731).
* Is limited to a maximum of 193 km/h (120 mph).

End speedo ref., begin component ref.

The OSS has no direct relation to your problem, but check the connector anyway.

Output Shaft Speed Sensor (OSS) 7H103:
The output shaft speed (OSS) sensor is a magnetic pickup, located at the output shaft ring gear that sends a signal to the powertrain control module to indicate transmission output shaft speed. The powertrain control module uses this signal for torque converter clutch control, shift scheduling, used in determining EPC pressure.
Symptoms:
No converter engagements, harsh shifts, abnormal shift schedules.
DTC: P0720, P0721
http://www.MyOnlineImages.com/Members/sdhartney/images/OSS.jpg

Vehicle Speed Sensor (VSS) 9E731:
The vehicle speed sensor is a magnetic pickup that sends a signal to the powertrain control module. This VSS signal tells the PCM vehicle speed. The PCM uses this signal to modify upshift schedules.
Symptoms:
Shift engagement/disengagement (hunting) on grades.
DTC: P0500, P0503, P1500, P1501, P1503
http://www.MyOnlineImages.com/Members/sdhartney/images/VSS.jpg

Hey Doug,
I've neglected to even ask, now I'm feeling dumb...

Is the cluster lit up at all?
If lit, what's the speed reading?
Any trouble codes present?


In either case I can provide diagnostics for 1996 only, these may also apply to 1995 & 1997.

Check my webpage (http://www24.brinkster.com/sdhartney/linc/linc.htm) in the right side column I've just uploaded two diags.
1 for Speedo Reads Zero and
1 for Cluster not illuminating

These are both in PPS format, let me know if PDF or PPT would suite you better.

Sorry for slow response-had to contact to owner. He says there is a display and it reads 0 all the time. For a while it would change to 1-2 mph but now only registers 0. Guess I'll be crawling under this thing next. Thanks. Doug