E: Speedometer/Odometer Reads Erroneously, Aerostar

E1 VERIFY CONDITION.


^ Refer to speedometer calibration tolerance specifications table in E7 . Be sure to check the odometer calibration. If both the odometer and speedometer are incorrect in the same direction it is usually a sign that the conversion constant tire size or speed sensor ring are different than programmed. A speedometer inaccurate with an accurate odometer is usually a problem with the speedometer module itself.


^ Are speedometer and odometer calibration within specified limits?


Yes

Speedometer normal.


No

GO to E2.



E2 CHECK FOR "NOT PROGRAMMED" MESSAGE


^ Does "ERROR 3" message alternate with normal odometer display?


Yes

GO to E7. RESET conversion constant.



REFER to Reset Conversion Constant in E7.

No

GO to E3



E3 CHECK TIRES/AXLE CAPACITY


^ Are tires the same size on opposite ends of a common axle and properly inflated?


Yes

DETERMINE conversion constant. GO to E5.


No

CORRECT condition or ADVISE customer. GO to E1



E4 VERIFY CONVERSION CONSTANT AND DISPLAY MODE


^ Check whether the conversion constant in the speedometer is correct with the following procedure: Press and hold the RESET button on the front of the speedometer while turning the key to RUN. Release the RESET button. The pointer will prove out and some codes will appear on the odometer display. If an "E" is on the left side of the display the module is programmed for English display mode and should have English (MPH) graphics. A lower case "o" signifies an overseas (KMH) graphics. Verify the graphics and display modes agree. (The number appearing after the type is the microprocessor revision level and is not used in this test.)Press and release the RESET button again. The conversion constant and the word CAL will be shown on the odometer display. Verify the programmed conversion constant is the same as that displayed on the chart or the constant calculated in E6. Turn off the key to exit this test.


^ Is the programmed conversion constant the same as that displayed on the chart or the constant calculated in E6?

Yes

REPLACE instrument cluster. VERIFY proper operation.


No

GO to E7.



E5 DETERMINE CONVERSION CONSTANT


^ Check tire size and type on vehicle rear axle or SAE average revs/mile. Refer to tire/axle capacity chart and note conversion constant.


^ Can the conversion constant be determined?


Yes

VERIFY conversion constant. GO to E4


No

GO to E6.



E6 MEASURE TIRE DIAMETER


^ To determine the conversion constant perform the following procedure: Hoist vehicle. Measure tire outside diameter (TOD). Note number of rear axle speed sensor teeth, speed sensor ring diameter, or axle capacity/tape group. Verify speed sensor ring diameter with identification tag attached to rear axle cover retaining bolts. If tag is missing manually count teeth.


NOTE: 7.5-inch rear axles have 102 teeth and 8.8-inch rear axles have 108 teeth.


Is outside diameter greater than 25.2 inches?







Yes

Use formula revs/mile = 1528 - (28x TOD) to calculate SAE average revs/mile. GO to E4


No

Revs/mile = 20,850/TOD. GO to E4.



E7 RESET CONVERSION CONSTANT


Re-program speed conversion constant using the following procedure: Locate the dealer mode programming enable connection. It is located behind the cowl side trim panel Insert metal clip in service wire panel connector. Clip other end to vehicle ground while the key is in the OFF position. Turn key to RUN (not crank) position while holding down the trip odometer RESET button on speedometer. Release RESET button. Speedometer will prove out (sweep across dial and back). The English/Metric and revision levels will be displayed.


The last number on the right side of display is the reprogramming lockout count This count shows the number of allowable conversion constants remaining. When the count is zero no additional changes can be made to this instrument cluster. If a conversion constant change is necessary a service instrument cluster must be ordered. Press and release RESET button again and PSOM conversion constant (without the decimal point) followed by the word CAL. Press and release the odometer SELECT button as many times as necessary to change conversion constant to the correct value.


NOTE: Pressing and releasing the RESET button to lock in the new conversion constant removes the number of times the PSOM can be re-programmed by one count. The module can only be re-programmed six times. If it is determined the original conversion constant is satisfactory, turn the key to OFF BEFORE the new constant is locked in.


When the correct new value is displayed in odometer window press and release the RESET button to lock in the new conversion constant. Turn the key off and remove the ground wire. Verify proper operation of the speedometer.


Is conversion constant set to desired value?







Yes

Procedure complete.


No

GO to E5