H: Speedometer/Odometer Inoperative (PSOM), Aerostar

H1 CHECK REAR ANTI-LOCK LAMP ILLUMINATION


^ Key to RUN.


^ Does anti-lock lamp on dash go out after self-test?


Yes

GO to H2 (display).


No

REFER to Antilock Brakes/Traction Control Systems/Testing and Inspection for diagnosis of anti-lock speed sensor, and speed sensor gear. Testing and Inspection



H2 CHECK ODOMETER DISPLAY

^ Is odometer display on, and do digits appear normal?


Yes

GO to H3.


No

GO to H6.



H3 CHECK FOR PRESENCE OF ERROR MESSAGE


NOTE: "ERROR 3" indicates the conversion constant must be programmed. See Pinpoint Test E. E: Speedometer/Odometer Reads Erroneously, Aerostar


^ Does the word "ERROR" appear on the odometer display?


Yes

REPLACE instrument cluster. VERIFY proper operation.


No

GO to H4.



H4 CHECK ODOMETER OPERATION


^ Odometer display increments mileage with vehicle motion or rear wheels turning?


Yes

GO to H9.


No

GO to H5.



H5 CHECK SPEEDOMETER OPERATION


^ Speedometer indication increases with increasing vehicle speed?


Yes

REPLACE instrument cluster. VERIFY proper operation.


No

GO to H8.



H6 CHECK SPEEDOMETER POWER FUSES


^ Remove check and reinstall battery power fuse #8 if intact.


^ Remove check and reinstall battery power fuse #17 if intact.


NOTE: If fuses are blown, replace with a new, intact fuse. If new fuse blows, determine cause and service as necessary.


^ With fuses intact, do the speedometer and odometer operate properly?


Yes

REPLACE instrument cluster. VERIFY proper operation.


No

Go to H7.



H7 CHECK SPEEDOMETER CONNECTOR VOLTAGES


^ Verify battery, ground and ignition available on Pins 1, 2 and 3 respectively with key in RUN.


NOTE: Only the wiring harness end of the connector should be probed.


^ Is resistance to ground less than 1 ohm with terminals in wiring harness connector completely seated in connector and locking tabs?


Yes

REPLACE instrument cluster.


No

SERVICE wiring harness and fuses as required. VERIFY proper operation.



H8 CHECK SPEED INPUT SIGNAL


^ Connect Rotunda Digital Volt-Ohmmeter 014-00407 or equivalent to Pin 4 (speed in +) and Pin 5 (speed in - ).


NOTE: Only the wiring harness end of the connector should be probed.


^ Does the voltage increase smoothly and continuously from 0 to approximately 3.5 volts as vehicle speed increases from 0 to 30 mph?


OR


^ If available a frequency counter may be connected to Pin 4 (speed in + ) and Pins (speed in - ).


^ Does the displayed frequency of the signal increase smoothly and continuously from 0 to approximately 667 Hz at approximately 30 mph?


OR


^ If neither a voltmeter nor frequency counter is available vehicle speed control may be used as a good indicator. If it works normally then the speedometer module is at least receiving a speed input signal and the wiring and sensor can be assumed to be good.


^ Does the speed control work normally?


Yes

REPLACE instrument cluster.


No

SERVICE wiring. CHECK for open or shorted wiring. If no problems are found, REFER to Antilock Brakes/Traction Control Systems. Antilock Brakes / Traction Control Systems



H9 CHECK SPEEDOMETER OPERATION


Does speedometer indication increase with increasing vehicle speed?


Yes

Normal operation. ADVISE customer.


No

REPLACE instrument cluster.