LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 1998 >> Yukon RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 70 (Automatic Transmission Diagnosis - 4L80-E (Gasoline)) >> Diagnostic Tests >> DTC P0748: Pressure Control Solenoid (PCS) Electrical Malfunction >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page does not describe the selected car, but rather 14 other vehicles, including the 1998 GMC Savana Special, 1998 GMC Savana Camper Special, 1998 GMC Savana, 1998 Chevrolet RV Cutaway, and 1998 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
  1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
  2. Start engine. Using scan tool, apply 0.1-1.0 amps and observe scan tool display. If PCS actual amperage reading is not within 0.16 amps of desired reference amperage reading, go to next step. If PCS actual amperage reading is within 0.16 amps of desired reference amperage reading, see DIAGNOSTIC AIDS.
  3. Turn ignition off. Disconnect transmission 20-pin connector. Install Jumper Harness (J-39885) to transmission side of 20-pin connector. Using a DVOM, measure resistance between terminals "C" and "D" of transmission 20-pin connector. See Figure. If resistance is 3-7 ohms, go to step 5).
  4. If resistance is not 3-7 ohms, remove transmission oil pan. Disconnect PCS connector. Measure resistance between PCS terminals. If resistance is 3-7 ohms, check for open in wiring harness. Repair wiring as necessary, then go to step 7). If resistance is not 3-7 ohms, replace PCS, then go to step 7).
  5. Measure resistance between ground and terminal "C" of transmission 20-pin connector. See Figure. If resistance is less than 9 ohms, check for short to ground in PCS high circuit. Repair as necessary, then go to step 7). If circuit is okay, replace PCS, then go to step 7). If resistance is more than 9 ohms, go to next step.
  6. Disconnect jumper harness from transmission 20-pin connector. Reconnect 20-pin connector. Disconnect appropriate VCM connector for PCS circuits. See WIRING DIAGRAMS . Using a DVOM, measure resistance between ground and PCS high circuit of VCM connector. If resistance is more than 9 ohms, check for open in PCS circuits. Repair as necessary, then go to next step. If circuits are okay, replace VCM, then go to next step. If resistance is less than 9 ohms, check for short to ground in PCS circuits. Repair as necessary, then go to next step. If circuits are okay, replace VCM, then go to next step.
  7. After repair is complete, select DTC on scan tool. Select "Clear Info" function. With engine running, ensure difference between PCS actual amperage reading and desired reference amperage reading is less than 0.16 amps. Select "Specific DTC" and enter DTC "P0748". If DTC P0748 is not present, repair is complete. If DTC P0748 is still present, repeat test.
scientia non olet · About LEMON Manuals