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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 55 (Automatic Transaxle Diagnosis - 4T65-E) >> Diagnostic Tests >> DTC P1810: Transmission Fluid Pressure Manual Valve Position Switch Malfunction >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Buick Regal, 2002 Buick Century, 2001 Buick Regal, and 2001 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the diagnostic system check? If so, go to next step. If not, see DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Did you perform the transmission fluid checking procedure? If so, go to next step. If not, perform the transmission fluid checking procedure. See appropriate AUTOMATIC article in TRANSMISSION SERVICING.
  3. Install a scan tool. Turn ignition on, engine off. Before clearing the DTCs, use the scan tool to record the freeze frame and failure records for reference. Using the CLEAR INFO function will erase the stored freeze frame and failure records from the PCM. Record the freeze frame and failure records. Clear the DTC. Start the engine and idle at normal operating temperature. With a scan tool, observe the TFP switch parameter. Apply the brakes. Select each transaxle range: P, R, N, D4, D3, D2 and D1. Does each selected transaxle range match the transaxle range displayed on the scan tool? If so, see DIAGNOSTIC AIDS  . If not, go to next step.
  4. Inspect the transaxle linkage from the range selector to the manual shift shaft for proper adjustment. See appropriate AUTOMATIC article in TRANSMISSION SERVICING. Did the linkage require adjustment? If so, go to step  16 . If not, go to next step.
  5. Turn ignition off. Disconnect the transaxle in-line 20-way connector (additional DTCs may set). Turn ignition on, engine off. With a scan tool, observe the TFP switch A/B/C parameter. Does the scan tool TFP switch A/B/C parameter indicate HI for all range signals "A", "B" and "C"? If so, go to next step. If not, go to step  9 .
  6. Turn ignition off. Install the Jumper Harness (J 44152) on the engine side of the transaxle in-line 20-way connector. Turn ignition on, engine off. Using a DVOM and a Connector Test Adapter Kit (J 35616-A), measure the voltage from terminal "N" of the jumper harness to ground. Measure the voltage from terminal "R" of the jumper harness to ground. Measure the voltage from terminal "P" of the jumper harness to ground. Does the voltage measure greater than 10 volts? If so, go to next step. If not, go to step  10 .
  7. Connect a fused jumper wire from terminal "N" of the jumper harness (signal "A" circuit) to ground while monitoring the scan tool TFP switch A/B/C parameter. When signal "A" circuit (CKT 1224) is grounded, do any other signal circuits indicate LOW? If so, go to step  11 . If not, go to next step.
  8. Connect a fused jumper wire from terminal "R" of the jumper harness (signal "B" circuit) to ground while monitoring the scan tool TFP switch A/B/C parameter. When signal "B" circuit (CKT 1225) is grounded, do any other signal circuits indicate Low? If so, go to step  11 . If not, go to step  12 .
  9. Test the signal circuits (CKTs 1224, 1225 and 1226) of the TFP manual valve position switch, that did not indicate HI, for a short to ground between the PCM connector and the transaxle in-line 20-way connector. Did you find and correct the condition? If so, go to step  16 . If not, go to step  15 .
  10. Test the signal circuits (CKTs 1224, 1225 and 1226) of the TFP manual valve position switch, that did not indicate proper voltage, for an open between the PCM connector and the transaxle in-line 20-way connector. Did you find and correct the condition? If so, go to step  16 . If not, go to step  15 .
  11. Test the affected signal circuits of the TFP manual valve position switch for a shorted together condition between the PCM connector C1 or C2 and the transaxle in-line 20-way connector. Did you find and correct the condition? If so, go to step  16 . If not, go to step  15 .
  12. Test the following circuits:
    • Test the signal "A" circuit (CKT 1224) of the TFP manual valve position switch for an open, short to ground or short to other signal circuits "B" or "C", between the transaxle in-line 20-way connector and the TFP manual valve position switch.
    • Test the signal "B" circuit (CKT 1225) of the TFP manual valve position switch for an open, short to ground or short to other signal circuits "A" or "C", between the transaxle in-line 20-way connector and the TFP manual valve position switch.
    • Test the signal C circuit (CKT 1226) of the TFP manual valve position switch for an open, short to ground or short to other signal circuits "A" or "B", between the transaxle in-line 20-way connector and the TFP manual valve position switch.

    Did you find a condition? If so, go to next step. If not, go to step  14 .

  13. Replace the transaxle internal wiring harness assembly. See TRANSAXLE INTERNAL WIRING HARNESS  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  16 .
  14. Replace the TFP manual valve position switch. See TRANSMISSION FLUID PRESSURE MANUAL VALVE POSITION SWITCH  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  16 .
  15. Replace the PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to next step.
  16. Perform the following procedure to verify the repair: Select DTC. Select CLEAR INFO. Operate the vehicle under the following conditions:
    • Start the engine and idle in Park for at least 60 seconds.
    • Drive the vehicle in D4 at greater than 5 MPH for at least one second.
    • The throttle angle must be greater than 9 percent.

    Select SPECIFIC DTC. Enter DTC P1810. Has the test run and passed? If so, system is okay. If not, go to step  1 .

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