Alex Pennace
March 10, 2008

1989 Lincoln Town Car


As of 2008-03-09 the car had 169210.2 miles on the odometer.


Current Issues

The TV cable on the AOD on the Lincoln Town Car

Occasionally the TV lever at the transmission gets siezed and will not go back. The net result is the transmission thinks the accelerator is all the way to the floor all the time. Symptoms: late shifting, and in extreme cases torque converter stall.

Digital Instrument Cluster

My Town Car has the conventional instrument cluster. I'd like to convert it to the digital instrument cluster someday. This section has some disorganized thoughts on the matter.

Message Center Display

The message center display (part -10D898-) is to the right of the speedometer. It is capable of displaying one row of six alphanumeric characters above a row of 14 characters. These characters may be represented with 15 segment displays.

The message center display apparently has an on-board character table of 64 characters, including one blank character. According to the manual page 33-62-20, the message center module tests this glyph table by displaying four messages, each with 20 characters, perhaps in ascending order, and the manual suggests that the message center display is faulty if any of the characters are incorrectly displayed.

The characters are thought to be: checkmark, A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, r, /\, m, -, h, ", ", $,>, <,>, <, ', (, ), *, |, !, -, space, /, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, +, ?, ←, =, → K. This list is surely incomplete. If you have a Lincoln Town Car with a digital instrument cluster and a digital camera, please help by following these steps:

  1. Press all message center buttons, from left to right, one at a time.
  2. Choose four buttons that produced a tone when pressed, and press all four of these at once.
  3. Keep pressing these four buttons until you go through the flashing display test.
  4. You are now at the character test phase. Take a picture of what is displayed, press those same four buttons, take a picture, repeat until it says "RAM PASSED."
  5. Forward the pictures to me by email.

The closest driver chip found so far is the HPDL-1414, and that seems to be a distant candidate. Another candidate is the ICM7423.

The message center display perhaps has eight modes of flashing. Mode 0 is no flashing, mode 7 is all flashing, and modes 1-6 are various characters in the message flash. Flashing is a per-message attribute, not a per-character attribute.

The message center module apparently communicates with the message center display over a serial link. Assuming each character is six bits long and the flash attribute is three bits long, the message can be expressed in 123 bits. Most likely the five bits between 123 and the nearest power of 2, 128, are not wasted. So perhaps the entire message is refereshed with 128 bits.

Setting the clock on the digital instrument cluster

One person has asked how to set the clock on a 1989 Lincoln Town Car with the digital instrument cluster. From the owner's manual:
  1. Press "Reset" button.
  2. Press "Clock" button. Hours should flash.
  3. Press "Adv" button to advance to correct hour and AM/PM indication.
  4. Press "Clock" button. Minutes should flash. Set with "Adv" button.
  5. Use "Clock" and "Adv" to set day, month and so forth. Press "Reset" when finished setting clock.


Any other thoughts?

Feel free to send me email with questions or comments.