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tsb902512vaccruise06pinout.jpg | Hits: 1972 | Posted on: 1/1/07
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ABNORMAL OPERATION DURING "ACCEL" OR "COAST"
In 1986-88 models, the vehicle may exhibit hesitation while using the COAST mode, or hesitation and dropout while using the ACCELmode. This abnormal operation is caused by poor contact between the speed control brushes and the slip rings on the steering wheel. This poor contact is due to a buildup of contamination of the lubricating grease. The condition occurs more frequently when the temperature is hot and on vehicles with high mileage.
Correct the concern by removing the steering wheel and thoroughly cleaning the grease from the brushes and slip rings. Regrease using grease (E8AZ-19590-A). This new grease has been used in production since the beginning of the 1989 Model Year. Its use has resulted in a 90% reduction in the incidence of this concern.
SPEED CONTROL PERFORMANCE - AOD, AXOD AND MTX5
As noted in the Owner's Guide, it may be preferable to shift the AOD or AXOD to the "D" (overdrive lockout) or the MTX5 to 4th gear in mountainous areas or at high altitude to improve speed control performance.
On steep upgrades the vehicle may not be able to maintain speed while in overdrive, or 5th gear, resulting in a speed drop below the set speed. If the speed drop exceeds approximately 10-13 MPH, the speed control will automatically disengage and must be reset with the SET/ACCEL button. Performance will be improved by shifting to "D" (AOD or AXOD) or to 4th (MTX5).
If speed control performance is poor on moderate grades, the adjustment of the Bowden cable/bead chain should be checked and readjusted if necessary. The automatic transmission shift linkage should also be checked for proper adjustment.
STAND ALONE SPEED CONTROL VOLTAGE/RESISTANCE TEST CONNECTIONS
Refer to Figure 1 and locate Circuit 203 (orange/light blue). It is used ONLY on the 1991 Lincoln Town Car with electronic cluster. This circuit connects the speed control amplifier to a speed control "set" indicator which is located at the lower edge of the electronic cluster center section. The voltage at circuit 203 is normally 5.0V (speed control not set) and less than 1.0V when the speed control is set. Grounding circuit 203 pin will light the cluster display. The SPEED CONTROL display will light only when a set speed is being maintained and when using ACCEL or RESUME. The display will turn off when braking, using OFF or COAST, with the ignition off.
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