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Home >> Chevrolet >> 1999 >> Venture Base, Van Cargo Extended >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Instrument Panel Displays & Instrument Panel Gages >> System Tests >> Speedometer Gauge &/Or Odometer Inoperative Or Inaccurate

Speedometer Gauge &/Or Odometer Inoperative Or Inaccurate

  1. If vehicle has been checked for Diagnostic Trouble Codes (DTCs), go to next step. If vehicle has not been checked for DTCs, go to appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
  2. Connect a scan tool to Data Link Connector (DLC). Drive vehicle and compare vehicle speed displayed on scan tool to speed displayed on speedometer gauge. If both speeds are similar, go to next step. If both speeds are not similar, go to step  6 .
  3. If both speedometer and odometer are inaccurate, go to next step. If only speedometer or odometer is inaccurate, go to step  17 .
  4. Check vehicle for correct tire size, PCM calibration and vehicle speed sensor application. If these component applications are not correct, go to next step. If these component applications are okay, diagnose and repair DTC P0502 (Vehicle Speed Sensor Circuit Low Input). See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
  5. Replace tires or vehicle speed sensor, or recalibrate PCM as necessary. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. Recheck system operation.
  6. Disconnect PCM Blue 80-pin connector C1. Turn ignition on. Using DVOM, check voltage between ground and harness connector C1 terminal No. 55 (Dark Green wire). If 9-10 volts does not exist, go to next step. If 9-10 volts exists, go to step  18 .
  7. Turn ignition on. Check voltage between underhood accessory wiring junction block connector C1 terminal E5 (Dark Green wire) and ground. If 9-10 volts exists, go to next step. If 9-10 volts does not exist, go to step  9 .
  8. Repair open circuit No. 389 (Dark Green wire) between underhood accessory wiring junction block connector C1 terminal E5 and PCM connector C1 terminal No. 55. Recheck system operation.
  9. Disconnect underhood accessory wiring junction block connector C1. Turn ignition on. Check voltage (backprobe) between underhood accessory wiring junction block connector C2 terminal D8 and ground. If 9-10 volts exists, go to next step. If 9-10 volts does not exist, go to step  11 .
  10. Repair short to ground on circuit No. 389 (Dark Green wire) between underhood accessory wiring junction block connector C1 terminal E5 and PCM connector C1 terminal No. 55. Recheck system operation.
  11. Disconnect underhood accessory wiring junction block connector C2. Remove Dark Green wire from connector C2 terminal E8. Reconnect connector. Turn ignition on. Check voltage (backprobe) between underhood accessory wiring junction block connector C2 terminal D8 and ground. If 9-10 volts does not exist, go to next step. If 9-10 volts exists, check for short to ground on Dark Green wire between underhood accessory wiring junction block and BCM, rear side door actuator control module and driver information display. Repair as necessary. See WIRING DIAGRAMS  . If wiring is okay, disconnect each module or component individually to isolate shorted module or component. Replace as necessary and retest system.
  12. Disconnect underhood accessory wiring junction block connector C2. Reconnect Dark Green wire from connector C2 terminal E8. Remove Dark Green wire from connector C2 terminal C8. Reconnect connector. Turn ignition on. Check voltage (backprobe) between underhood accessory wiring junction block connector C2 terminal D8 and ground. If 9-10 volts does not exist, go to next step. If 9-10 volts exists, check for short to ground on Dark Green wire between underhood accessory wiring junction block and cruise control module and radio. Repair as necessary. If wiring is okay, disconnect each component individually to isolate shorted component. Replace as necessary and retest system.
  13. Disconnect underhood accessory wiring junction block connector C2. Reconnect Dark Green wire from connector C2 terminal C8. Turn ignition on. Check voltage (backprobe) between underhood accessory wiring junction block connector C2 terminal D8 and ground. If 9-10 volts exists, go to next step. If 9-10 volts does not exist, go to step  15 .
  14. Replace underhood accessory wiring junction block. Recheck system.
  15. Reconnect connector. Turn ignition on. Check voltage (backprobe) between instrument cluster connector C2 terminal "N" (Dark Green wire) and ground. If 9-10 volts exists, go to next step. If 9-10 volts does not exist, go to step  17 .
  16. Repair open circuit in Dark Green wire between instrument cluster connector C2 terminal "N" and underhood accessory wiring junction block connector C2 terminal D8. Recheck system.
  17. Replace instrument cluster. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Recheck system operation.
  18. Reconnect PCM connector C1. Using DVOM capable of reading Hertz, backprobe connector C220 terminal C7 (Dark Green wire) and connect other meter lead to ground. Drive vehicle at 35 MPH. If reading is 36-42 Hz, go to step  17 . If reading is not 36-42 Hz, go to step  19 .
  19. Replace PCM. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. Recheck system.
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