Message center is bonkers!!

[drwambo]

HI folks, new to the Explorer arena - 96 EB....Got a question about the message center. Mileage is all fouled up. When watching the elapsed mileage counter at a stop sign, the 10ths just click away like I'm going about 40. How does the system receive its speed signal? Does the real ODO (looks mechanical) get its info from the same sensor, or is it a cable. Any help trying to figure this out would be appreciated - I'm a computer jock by trade, and this is driving me CRAZY!

 

[Jon_Herr]

This is a brown response

I saw a newer full size ford with a jumpy speedo due to noise / bad connection / etc with the pickup assembly.

I don't know how the message center gets it's timing - prolly from the EEC since it's capable of calculating miles / gallon / speed.

The EEC must know the vehicle speed in order to control the transmission correctly.

From all of this my three main suspects are:
1. Bad connection / broken connector
2. REALLY noisy 12V - maybe something has failed in the charging system?
3. Bad sensor
4. Bad message center
5. Bad ECU

Now for the brown part. Since I have no schematic or system diagram, I've pulled all of this out of my arse.

Good Luck.